Iodine-based dual-energy CT predicts early neurological decline from cerebral edema after large hemispheric infarction

Background & Purpose

Ischemia affecting two thirds of the MCA territory predicts development of malignant cerebral edema. However, early infarcts are hard to diagnose on conventional head CT. We hypothesize that high-energy (190keV) virtual monochromatic images (VMI) from dual-energy CT (DECT) imaging enables earlier detection of secondary injury from malignant cerebral edema (MCE).

Methods

Consecutive LHI patients with NIHSS ≥ 15 and DECT within 10 hours of reperfusion from May 2020 to March 2022 were included. We excluded patients with parenchymal hematoma-type 2 transformation. Retrospective analysis of clinical and novel variables included VMI Alberta Stroke Program Early CT Score (ASPECTS), total iodine content, and VMI infarct volume. Primary outcome was early neurological decline (END). Secondary outcomes included hemorrhagic transformation, decompressive craniectomy (DC), and medical treatment of MCE. Fisher's exact test and Wilcoxon test were used for univariate analysis. Logistic regression was used to develop prediction models for categorical outcomes.

Results

Eighty-four LHI patients with a median age of 67.5 [IQR 57,78] years and NIHSS 22 [IQR 18,25] were included. Twenty-nine patients had END. VMI ASPECTS, total iodine content, and VMI infarct volume were associated with END. VMI ASPECTS, VMI infarct volume, and total iodine content were predictors of END after adjusting for age, sex, initial NIHSS, and tPA administration, with a AUROC of 0.691 [0.572,0.810], 0.877 [0.800, 0.954], and 0.845 [0.750, 0.940]. By including all three predictors, the model achieved AUROC of 0.903 [0.84,0.97] and was cross validated by leave one out method with AUROC of 0.827.

Conclusion

DECT with high-energy VMI and iodine quantification is superior to conventional CT ASPECTS and is a novel predictor for early neurological decline due to malignant cerebral edema after large hemispheric infarction.

Impact of Enteral Albuterol on Bradycardic Events After Acute Cervical Spinal Cord Injury

BACKGROUND

Acute cervical spinal cord injury (ACSCI) is commonly complicated by spinal shock, resulting in hemodynamic instability characterized by bradycardia and hypotension that can have fatal consequences. Current guidelines recommend the use of intravenous beta and dopamine agonists, such as norepinephrine and dopamine, respectively. We sought to determine whether enteral albuterol would be a safe and feasible treatment for bradycardia without an increase in the occurrence of known side effects of albuterol in patients with ACSCI.

METHODS

A retrospective review of patients with ACSCI admitted to an intensive care unit at a level I trauma center and treated with enteral albuterol was conducted. Patients were excluded for the following reasons: pure beta blocker use prior to injury, concurrent use of pacemaker, age of less than 18 years, or age more than 75 years. As part of the standard of care, all patients underwent mean arterial pressure (MAP) augmentation to reach a goal of greater than 85 mm Hg during the first 7 days post injury. All eligible patient charts were reviewed for demographic characteristics, daily minimum and maximum heart rate and MAP, and concomitant vasoactive medication use. Bradycardia and tachycardia were defined as heart rate less than 60 beats per minute (bpm) and greater than 100 bpm, respectively. Factors found to be associated with bradycardia on univariate analysis were entered into a multivariable generalized estimating equation analysis to determine factors independently associated with bradycardia during the study period.

RESULTS

There were 58 patients with cervical ASCI (age 45 ± 18 years, 76% men) admitted between January 1, 2016, and December 31, 2017, that met the study criteria. The mean time to initiation of albuterol was 1.5 ± 1.7 days post injury, with a duration of 9.3 ± 4.5 days and a mean daily dosage of 7.8 ± 4.5 mg. Bradycardia was observed in 136 of 766 patient days (17%). There were a few episodes of hyperglycemia (1%) and tachycardia (3%), but no episodes of hypokalemia. In a multivariable analysis, female sex (P = 0.006) and American Spinal Cord Injury Association grade A, B, or C (P < 0.001) were associated with a higher risk of developing bradycardia, whereas dosage of albuterol (P = 0.009) and norepinephrine use (P = 0.008) were associated with a lower risk of developing bradycardia.

CONCLUSIONS

Albuterol administration in ASCI is a safe and feasible treatment for bradycardia, given that no significant side effects, such as hyperglycemia, hypokalemia, or tachycardia, were observed. The administration of enteral albuterol was well tolerated and, in a dose-dependent manner, associated with a lower occurrence of bradycardia. Further prospective trials for the use of enteral albuterol after SCI are warranted.

Verticalization for Refractory Intracranial Hypertension: A Case Series

BACKGROUND

Severe intracranial hypertension is strongly associated with mortality. Guidelines recommend medical management involving sedation, hyperosmotic agents, barbiturates, hypothermia, and surgical intervention. When these interventions are maximized or are contraindicated, refractory intracranial hypertension poses risk for herniation and death. We describe a novel intervention of verticalization for treating intracranial hypertension refractory to aggressive medical treatment.

METHODS

This study was a single-center retrospective review of six cases of refractory intracranial hypertension in a tertiary care center. All patients were treated with a standard-of-care algorithm for lowering intracranial pressure (ICP) yet maintained an ICP greater than 20 mmHg. They were then treated with verticalization for at least 24 h. We compared the median ICP, the number of ICP spikes greater than 20 mmHg, and the percentage of ICP values greater than 20 mmHg in the 24 h before verticalization vs. after verticalization. We assessed the use of hyperosmotic therapies and any changes in the mean arterial pressure and cerebral perfusion pressure related with the intervention.

RESULTS

Five patients were admitted with subarachnoid hemorrhage and one with intracerebral hemorrhage. All patients had ICP monitoring by external ventricular drain. The median opening pressure was 30 mmHg (25th-75th interquartile range 22.5-30 mmHg). All patients demonstrated a reduction in ICP after verticalization, with a significant decrease in the median ICP (12 vs. 8 mmHg; p < 0.001), the number of ICP spikes (12 vs. 2; p < 0.01), and the percentage of ICP values greater than 20 mmHg (50% vs. 8.3%; p < 0.01). There was a decrease in total medical interventions after verticalization (79 vs. 41; p = 0.05) and a lower total therapy intensity level score after verticalization. The most common adverse effects included asymptomatic bradycardia (n = 3) and pressure wounds (n = 4).

CONCLUSIONS

Verticalization is an effective noninvasive intervention for lowering ICP in intracranial hypertension that is refractory to aggressive standard management and warrants further study.

Triage of Patients with Intracerebral Hemorrhage to Comprehensive Versus Primary Stroke Centers

OBJECTIVES

The management of patients admitted with intracerebral hemorrhage (ICH) mostly occurs in an ICU. While guidelines recommend initial treatment of these patients in a neurocritical care or stroke unit, there is limited data on which patients would benefit most from transfer to a comprehensive stroke center where on-site neurosurgical coverage is available 24/7. As neurocritical units become more common in primary stroke centers, it is important to determine which patients are most likely to require neurosurgical intervention and transfer to comprehensive stroke centers.

MATERIALS AND METHODS

This is a retrospective observational cohort study conducted at an academic comprehensive stroke center in the United States. Four-hundred-fifty-nine consecutive patients transferred or directly admitted to the neurocritical care unit from 2016-2018 with the primary diagnosis of ICH were included. Univariate statistics and multivariate regression were used to identify clinical characteristics associated with neurosurgical intervention, defined as undergoing craniotomy, ventriculostomy, or endovascular embolization of an arteriovenous malformation (AVM).

RESULTS

The following variables were associated with neurosurgical intervention in multivariate analysis: age (OR 0.38, 95% CI 0.27-0.55), admission Glasgow Coma Scale (OR 0.29, 95% CI 0.18-0.48), the presence of intraventricular hemorrhage (OR 2.82, CI 1.71-4.65), infratentorial location of ICH (OR 2.28, 95% CI 1.20-4.31), previous antiplatelet use (OR 2.04, 95% CI 1.24-3.34), and an AVM indicated on CT Angiogram (OR 2.59, 95% CI 1.19-5.63) were independently associated with the need for neurosurgical intervention. This was translated into a scoring system to help make quick triage decisions, with high sensitivity (99%, 95% CI 97-99%) and negative predictive value (98%, 95% CI 89-99%).

CONCLUSIONS

Using previously well described predictors of severity in ICH patients, we were able to develop a scoring system to predict the need for neurosurgical intervention with high sensitivity and negative predictive value.

Development of Neurological Emergency Simulations for Assessment: Content Evidence and Response Process

OBJECTIVE

To document two sources of validity evidence for simulation-based assessment in neurological emergencies.

BACKGROUND

A critical aspect of education is development of evaluation techniques that assess learner's performance in settings that reflect actual clinical practice. Simulation-based evaluation affords the opportunity to standardize evaluations but requires validation.

METHODS

We identified topics from the Neurocritical Care Society's Emergency Neurological Life Support (ENLS) training, cross-referenced with the American Academy of Neurology's core clerkship curriculum. We used a modified Delphi method to develop simulations for assessment in neurocritical care. We constructed checklists of action items and communication skills, merging ENLS checklists with relevant clinical guidelines. We also utilized global rating scales, rated one (novice) through five (expert) for each case. Participants included neurology sub-interns, neurology residents, neurosurgery interns, non-neurology critical care fellows, neurocritical care fellows, and neurology attending physicians.

RESULTS

Ten evaluative simulation cases were developed. To date, 64 participants have taken part in 274 evaluative simulation scenarios. The participants were very satisfied with the cases (Likert scale 1-7, not at all satisfied-very satisfied, median 7, interquartile range (IQR) 7-7), found them to be very realistic (Likert scale 1-7, not at all realistic-very realistic, median 6, IQR 6-7), and appropriately difficult (Likert scale 1-7, much too easy-much too difficult, median 4, IQR 4-5). Interrater reliability was acceptable for both checklist action items (kappa = 0.64) and global rating scales (Pearson correlation r = .70).

CONCLUSIONS

We demonstrated two sources of validity in ten simulation cases for assessment in neurological emergencies.

Crystalline characteristics of annealed AlN films by pulsed laser treatment for solidly mounted resonator applications

AlN films were deposited on Si substrates using a reactive RF magnetron sputtering process and then the films were annealed by using different laser powers and wavelengths (355 nm, 532 nm and 1064 nm). For all three laser systems, the (002) peak intensity was obviously improved following laser irradiation. The improvement in the crystalline property was particularly obtained in the AlN film processed at 355 nm. In particular, given the use of the optimal laser power (0.025 W), the (002) peak intensity was 58.7% higher than that of the as-deposited film. The resonant frequency and 3 dB bandwidth of a SMR filter with an unprocessed AlN film were found to be 2850 MHz and 227.81 MHz, respectively. Following laser treatment with a wavelength of 1064 nm and a power of 0.25 W, the resonant frequency changed from 2850 to 2858 MHz. Moreover, 3 dB bandwidth changed from 227.81 to 202.49 MHz and the return loss of the filter reduced from 17.28 to 16.48 dB. Overall, the results thus show that the frequency response of the SMR filter can be adjusted and the return loss reduced by means of laser treatment with an appropriate wavelength.

Implementation of a Clinical Pathway to Reduce Rates of Postextubation Stridor

BACKGROUND

Unsuccessful extubation is associated with increased intensive care unit and hospital length of stays, hospital costs, morbidity, and mortality. The most common cause of reintubation is laryngeal edema, often evidenced by postextubation stridor.

OBJECTIVE

To reduce the rates of postextubation stridor and reintubation in the neurocritical care unit at a large urban academic medical center.

METHODS

A clinical pathway was created to aid in detecting patients expected to experience postextubation stridor and to guide prophylactic treatment. During the 12-week implementation phase, the pathway was completed on all intubated patients daily.

RESULTS

The 12-week trial included a total of 606 days of mechanical ventilation. Checklists were completed for 531 days, a compliance rate of 88% for use of the clinical pathway. Of the 56 patients who were extubated during the trial, 54 had a checklist completed, for 96% compliance on the day of extubation. Outcomes after all nonpalliative extubations (n = 43) during the 12 weeks before and after implementation of the pathway (n = 56 periods) were evaluated by using χ ² tests. Implementation of the pathway was associated with a significant reduction in rates of postextubation stridor (χ ² = 6.2; P = .01), reintubation (χ ² = 5.5; P = .02), and reintubation due to postextubation stridor (χ ² = 8.3; P = .004).

CONCLUSION

The clinical pathway implemented in the neurocritical care unit was safe and effective in reducing rates of reintubation and reintubation due to postextubation stridor.

Interventions affecting blood pressure variability and outcomes after intubating patients with spontaneous intracranial hemorrhage

INTRODUCTION

Spontaneous intracranial hemorrhage (sICH) that increases intracranial pressure (ICP) is a life-threatening emergency often requiring intubation in Emergency Departments (ED). A previous study of intubated ED patients found that providing ≥5 interventions after initiating mechanical ventilation (pMVI) reduced mortality rate. We hypothesized that pMVIs would lower blood pressure variability (BPV) in patients with sICH and thus improve survival rates and neurologic outcomes.

METHOD

We performed a retrospective study of adults, who were transferred to a quaternary medical center between 01/01/2011 and 09/30/2015 for sICH, received an extraventricular drain during hospitalization. They were identified by International Classification of Diseases, version 9 (430.XX, 431.XX), and procedure code 02.21. Outcomes were BPV indices, death, and being discharged home.

RESULTS

We analyzed records from 147 intubated patients transferred from 40 EDs. Forty-one percent of patients received ≥5 pMVIs and was associated with lower median successive variation in systolic blood pressure (BP_SV) (31,[IQR 18-45) compared with those receiving 4 or less pMVIs (38[IQR 16-70]], p = 0.040). Three pMVIs, appropriate tidal volume, sedative infusion, and capnography were significantly associated with lower BPV. In addition to clinical factors, BP_SV (OR 26; 95% CI 1.2, >100) and chest radiography (OR 0.3; 95% CI 0.09, 0.9) were associated with mortality rate. Use of quantitative capnography (OR 8.3; 95%CI, 4.7, 8.8) was associated with increased likelihood of being discharged home.

CONCLUSIONS

In addition to disease severity, individual pMVIs were significantly associated with BPV and patient outcomes. Emergency physicians should perform pMVIs more frequently to prevent BPV and improve patients' outcomes.

Continuous Vital Sign Analysis to Predict Secondary Neurological Decline After Traumatic Brain Injury

Background: In the acute resuscitation period after traumatic brain injury (TBI), one of the goals is to identify those at risk for secondary neurological decline (ND), represented by a constellation of clinical signs that can be identified as objective events related to secondary brain injury and independently impact outcome. We investigated whether continuous vital sign variability and waveform analysis of the electrocardiogram (ECG) or photoplethysmogram (PPG) within the first hour of resuscitation may enhance the ability to predict ND in the initial 48 hours after traumatic brain injury (TBI).

Methods: Retrospective analysis of ND in TBI patients enrolled in the prospective Oximetry and Noninvasive Predictors Of Intervention Need after Trauma (ONPOINT) study. ND was defined as any of the following occurring in the first 48 h: new asymmetric pupillary dilatation (>2 mm), 2 point GCS decline, interval worsening of CT scan as assessed by the Marshall score, or intervention for cerebral edema. Beat-to-beat variation of ECG or PPG, as well as waveform features during the first 15 and 60 min after arrival in the TRU were analyzed to determine physiologic parameters associated with future ND. Physiologic and admission clinical variables were combined in multivariable logistic regression models predicting ND and inpatient mortality.

Results: There were 33 (17%) patients with ND among 191 patients (mean age 43 years old, GCS 13, ISS 12, 69% men) who met study criteria. ND was associated with ICU admission (P < 0.001) and inpatient mortality (P < 0.001). Both ECG (AUROC: 0.84, 95% CI: 0.76,0.93) and PPG (AUROC: 0.87, 95% CI: 0.80, 0.93) analyses during the first 15 min of resuscitation demonstrated a greater ability to predict ND then clinical characteristics alone (AUROC: 0.69, 95% CI: 0.59, 0.8). Age (P = 0.02), Marshall score (P = 0.001), penetrating injury (P = 0.02), and predictive probability for ND by PPG analysis at 15 min (P = 0.03) were independently associated with inpatient mortality.

Conclusions: Analysis of variability and ECG or PPG waveform in the first minutes of resuscitation may represent a non-invasive early marker of future ND.

Esophageal Cooling Device Versus Other Temperature Modulation Devices for Therapeutic Normothermia in Subarachnoid and Intracranial Hemorrhage

Achieving and maintaining normothermia (NT) after subarachnoid hemorrhage (SAH) or intracerebral hemorrhage (ICH) often require temperature modulating devices (TMD). Shivering is a common adverse effect of TMDs that can lead to further costs and complications. We evaluated an esophageal TMD, the EnsoETM (Attune Medical, Chicago, IL), to compare NT performance, shiver burden, and cost of shivering interventions with existing TMDs. Patients with SAH or ICH and refractory fever were treated with the EnsoETM. Patient demographics, temperature data, shiver severity, and amounts and costs of medications used for shiver management were prospectively collected. Controls who received other TMDs were matched for age, gender, and body surface area to EnsoETM recipients, and similar retrospective data were collected. All patients were mechanically ventilated. Fever burden was calculated as areas of curves of time spent above 37.5°C or 38°C. Demographics, temperature data, and costs of EnsoETM recipients were compared with recipients of other TMDs. Eight EnsoETM recipients and 24 controls between October 2015 and November 2016 were analyzed. There were no differences between the two groups in demographics or patient characteristics. No difference was found in temperature at initiation (38.7°C vs. 38.5°C, p = 0.4) and fever burden above 38°C (-0.44°C × hours vs. -0.53°C × hours, p = 0.47). EnsoETM recipients showed a nonsignificant trend in taking longer to achieve NT than other TMDs (5.4 hours vs. 2.9 hours, p = 0.07). EnsoETM recipients required fewer shiver interventions than controls (14 vs. 30, p = 0.02). EnsoETM recipients incurred fewer daily costs than controls ($124.27 vs. $232.76, p = 0.001). The EnsoETM achieved and maintained NT in SAH and ICH patients and was associated with less shivering and lower pharmaceutical costs than other TMDs. Further studies in larger populations are needed to determine the EnsoETM's efficacy in comparison to other TMDs.

Effect of root agglutinin on microbial activities in the rhizosphere

A total of 220 bacterial isolates were obtained from pea rhizosphere and nonrhizosphere samples. Of these samples, 100 isolates were chosen randomly to test for their agglutinative reaction against pea root exudate. The percentage of positive agglutination of bacteria isolated from the nonrhizosphere sample was significantly lower than that of bacteria isolated from the rhizosphere sample. Moreover, this agglutinative reaction could not be blocked either by treating the bacterial cells or root exudate with different carbohydrates before they were mixed or by boiling the root exudate first. Bacteria that could be agglutinated by pea root exudate followed the downward growth of the pea root through the soil profile. The greater abilities of such bacteria to colonize the pea rhizosphere were indicated by their higher rhizosphere-colonizing (rhizosphere/nonrhizosphere) ratios, whether the bacteria were added alone or together with nonagglutinating bacteria. However, bacteria did show different agglutinative reactions toward root exudates obtained from different plants.

Hybrid pulse anodization for the fabrication of porous anodic alumina films from commercial purity (99%) aluminum at room temperature

Most porous anodic alumina (PAA) or anodic aluminum oxide (AAO) films are fabricated using the potentiostatic method from high-purity (99.999%) aluminum films at a low temperature of approximately 0-10 degrees C to avoid dissolution effects at room temperature (RT). In this study, we have demonstrated the fabrication of PAA film from commercial purity (99%) aluminum at RT using a hybrid pulse technique which combines pulse reverse and pulse voltages for the two-step anodization. The reaction mechanism is investigated by the real-time monitoring of current. A possible mechanism of hybrid pulse anodization is proposed for the formation of pronounced nanoporous film at RT. The structure and morphology of the anodic films were greatly influenced by the duration of anodization and the type of voltage. The best result was obtained by first applying pulse reverse voltage and then pulse voltage. The first pulse reverse anodization step was used to form new small cells and pre-texture concave aluminum as a self-assembled mask while the second pulse anodization step was for the resulting PAA film. The diameter of the nanopores in the arrays could reach 30-60 nm.

UCP2 A55V variant is associated with obesity and related phenotypes in an aboriginal community in Taiwan

OBJECTIVE

Human uncoupling proteins 2 and 3 (UCP2 and UCP3) are two mitochondrial proteins that are involved in the control of metabolism of fatty acid and possibly protect against oxidative damage. The aim of this study was to analyze genetic associations of four polymorphisms of the UCP2 and UCP3 genes with insulin, leptin concentration and obesity in Taiwan aborigines.

RESEARCH METHODS

Four polymorphisms were compared in 324 obese (body mass index (BMI) > or =30 kg/m(2)) and overweight (30>BMI > or =25 kg/m(2)) subjects, and 114 normal weight subjects (BMI <25 kg/m(2)) in an aboriginal community of southern Taiwan. Anthropometric characteristics and fasting levels of insulin, leptin, triglycerides and cholesterol were measured.

RESULTS

Before and after adjusting for age distribution, only the Val55 allele in exon 4 of the UCP2 gene increased the risk of overweight and obesity (adjusted odds ratio (OR)=2.02, P=0.004) in comparison with Ala55. UCP2 V55V is also associated with higher fasting insulin levels than A55V (P=0.01) and A55A (P=0.04) in the obese/overweight group. Using the COCAPHASE program of the UNPHASED software, haplotype analysis of three single nucleotide polymorphisms (A55V-G866A-C-55T) revealed that A-G-C (73% in obese subjects and 77% in controls) was the most common haplotype and that the haplotype V-A-T (13% in obese subjects and 5% in controls) was significantly increased in obese and overweight subjects (BMI > or =25 kg/m(2)) (OR=2.62, P<0.001).

DISCUSSIONS

UCP2 A55V variant might predispose to obesity and Val55 allele to confer population-attributable risk for 9.5% of obese disorders and increase insulin concentrations. The V-A-T haplotype within UCP2-UCP3 gene cluster is also significantly associated with obesity in Paiwan aborigines.

Cytotoxicity induced by grape seed proanthocyanidins: role of nitric oxide

Grape seed proanthocyanidin extract (GPSE) at high doses has been shown to exhibit cytotoxicity that is associated with increased apoptotic cell death. Nitric oxide (NO), being a regulator of apoptosis, can be increased in production by the administration of GSPE. In a chick cardiomyocyte study, we demonstrated that high-dose (500 microg/ml) GSPE produces a significantly high level of NO that contributes to increased apoptotic cell death detected by propidium iodide and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining. It is also associated with the depletion of intracellular glutathione (GSH), probably due to increased consumption by NO with the formation of S-nitrosoglutathione. Co-treatment with L-NAME, a NO synthase inhibitor, results in reduction of NO and apoptotic cell death. The decline in reduced GSH/oxidized GSH (GSSG) ratio is also reversed. N-Acetylcysteine, a thiol compound that reacts directly with NO, can reduce the increased NO generation and reverse the decreased GSH/GSSG ratio, thereby attenuating the cytotoxicity induced by high-dose GSPE. Taken together, these results suggest that endogenous NO synthase (NOS) activation and excessive NO production play a key role in the pathogenesis of high-dose GSPE-induced cytotoxicity.

Mechanistic studies on the use of 2H- and 13C-analogues as internal standards in selected ion monitoring GC-MS quantitative determination--butalbital example

As a part of our study on the use of isotopic analogues as the internal standard (IS) for the quantitation of drug analytes, this article reports on the performance characteristics of 2H5-butalbital and 13C4-butalbital with particular focus on (1) determining and comparing the effectiveness of the 2H- and 13C-analogues in serving as the ISs for quantitation; (2) understanding the "cross-contribution" phenomenon underlying the effectiveness of selected ion pairs used for quantitation purpose; and (3) examining whether the same characteristics, observed in our preliminary report for the secobarbital/2H5-secobarbital/13C4-secobarbital system, also exist in the butalbital/2H5-butalbital/13C4-butalbital system. Adapting similar procedures applied to our previous study on the secobarbital system, we observed that (1) both labeled analogues (13C4-butalbital and 2H5-butalbital) cause more significant cross-contributions to ions designated for butalbital than butalbital to the labeled analogues; (2) compared to 2H5-butalbital, 13C4-butalbital appears to cause less cross-contributions to ions designated for butalbital; (3) cross-contribution between the following ion pairs are minimal: m/z 200/196, 199/195, 185/181 (13C4-butalbital as the IS) and m/z 201/196 (2H5-butalbital as the IS). It is also concluded that the butalbital/2H5-butalbital system exhibits the same concentration dependency phenomenon observed in the secobarbital/ 2H5-secobarbital system, that is, ratios of ion pairs designated for these two isotopic analogues (resulting from routine gas chromatography-mass spectrometry protocol) increase as their concentrations are diluted. (In parallel with the secobarbital/13C4-secobarbital system, the butalbital/13C4-butalbital system does not exhibit this phenomenon.)

Isotopic analogs as internal standards for quantitative analyses by GC/MS--evaluation of cross-contribution to ions designated for the analyte and the isotopic internal standard

Isotopic analogs of the analytes are currently preferred internal standards (IS) for quantitative analyses of drugs and their metabolites in biological matrices by GC/MS procedures. Contributions of the analyte and the IS to the intensities of ions designated for the IS and the analyte, respectively--an undesirable phenomenon termed "cross-contribution"--greatly weakens the effectiveness of this approach. The cross-contribution phenomenon has been, in the past, evaluated by a "direct measurement" approach, in which intensities of interested ions were measured in two separate experiments using equal quantities of the analyte and the IS. Alternate procedures that may generate improved results are hereby studied. For the "improved direct measurement" approach, ion intensity data derived from the previously reported direct measurement procedure are first normalized before being used to calculate the extent of cross-contribution. An "internal standard" approach is also developed, in which a set amount of a third compound is incorporated into these two separate experiments, thus allowing corrections of ion intensity data that are imbedded with variations inherent to separate experiments. Finally, a "standard addition" approach, involving a series "addition" of "standards", generates multiple data points; thus, providing a mechanism to validate the resulting cross-contribution data. Secobarbital/(2)H(5)-secobarbital and secobarbital/(13)C(4)-secobarbital pairs are adapted as the exemplar systems for this study.

Components of insulin resistance syndrome in a community-based population assessed by log-linear models

BACKGROUND AND PURPOSE

To investigate the clustering of insulin resistance syndrome with hyperinsulinemia, hypertriglyceridemia, low high-density lipoprotein (HDL) cholesterol, hypertension, and obesity, we conducted this cross-sectional study and analyzed the patterns of conditional independence among these five elements.

METHODS

Fasting insulin, lipid profiles, blood pressure, and anthropometric data from 2165 Taiwanese older than 35 years in the Chin-Shan community were examined. The cut-off points of these five factors (all binary variables) were defined. The hierarchical log-linear regression with nested effects model was applied to fit this higher-order contingency table of five variables, and likelihood ratio (chi2) statistics were used to test the goodness of fit.

RESULTS

Hyperinsulinemia was independently correlated with obesity (odds ratio [OR] 5.7, 95% confidence interval [CI] 4.5-7.3), low HDL (OR 2.3, 95% CI 1.8-2.9), and hypertriglyceridemia (OR 1.6, 95% CI 1.2-2.2). Hypertriglyceridemia was significantly associated with low HDL (OR 3.6, 95% CI 2.7-4.8), and non-significantly associated with hypertension (OR 1.3, 95% CI 0.9-1.7) and obesity (OR 1.1, 95% CI 0.8-1.6). In persons with normal triglyceride levels, hypertension was positively associated with obesity (OR 2.8, 95% CI 2.1-3.7) and low HDL (OR 2.0, 95% CI 1.5-2.8). Analyses from forward and backward selection methods gave similar results. Graphical models with conditional independence relationships among these five variables were demonstrated.

CONCLUSIONS

The components of insulin resistance syndrome have intricate relationships. Hyperinsulinemia was most related to obesity, and hypertriglyceridemia was most related to low HDL.

An Internet-based utility assessment of breast hypertrophy

The Internet has changed the way people shop, do business, and communicate with one another. Even those who try to avoid computers are bombarded with Web advertisements on television and in newspapers and magazines. The Internet also has excellent, but still largely underused, potential for conducting research studies. A Web-based questionnaire essentially combines the power and graphic flexibility of a computer with the freedom of a mail survey. The specific goals of this study were (1) to develop a Web-based utility assessment tool and (2) to use this tool to measure the health burden of breast hypertrophy by using the Internet to sample a population. An open-enrollment, Internet-based survey was developed to assess societal preferences for mild and severe breast hypertrophy using three established assessment techniques: visual analogue scale, time trade-off, and standard gamble. Subjects were recruited from a Web-based clinical trial listing service. Demographics, subjects' utility for their current health, and responses to a comorbidity index were also recorded. Data were recorded from August 1, 1999, to January 31, 2000. There were 480 unique responses, and 356 (74 percent) met the inclusion criteria. The respondents were predominantly female (81 percent), Caucasian (83 percent), and in the middle income brackets. Their mean age was 32.9. The average score for capacity of understanding was 4.99 out of 5 (5 = excellent). The median utility score for severe breast hypertrophy (visual analogue scale, 0.70; time trade-off, 0.85; standard gamble, 0.88) differed significantly from the median utility score for mild breast hypertrophy (visual analogue scale, 0.93; time trade-off, 1.0; standard gamble, 0.98) for each method. The results showed that the construction of a Web-based questionnaire for utility assessment is feasible and can be used to capture the utility of health states. The authors were able to enroll a large number of subjects with excellent capacity to understand the study, resulting in a high rate of usable responses. The applicability of these data to cost-effectiveness studies is limited by the extent to which the sampled population of this study is representative of society in general. The demographics of this study sample also differed from those of the Internet population. The study was piloted by measuring the values for breast hypertrophy, but the procedure could be used to assess the burden on quality of life of any disease and, potentially, the efficacy of surgical interventions. The study method is recommended as an accurate and cost-effective alternative for measuring quality of life.

Arterial tissue of arsenic, selenium and iron in Blackfoot disease patients

In order to identify arsenic as one of the major factors that cause Blackfoot disease on the southwest coast of Taiwan, an atomic absorption spectrophotometric method was used to determine arsenic, selenium and iron concentrations in the tissue of plantar digital arteries. Samples from 31 patients with Blackfoot disease and 30 controls with road traffic accident or occupational injuries were studied. The results indicate that the arterial tissue from Blackfoot disease patients had higher arsenic concentration (3.06+/-1.42 microg/g) than that from healthy controls (0.59+/-0.28 microg/g). The variability was very large 418% at p<0.001. It was also noted that the concentrations of selenium (1.23+/-0.41 microg/g and 1.05+/-0.13 microg/g in patients and controls respectively; with variability 17.1%) and iron (72.7+/-34.9 microg/g and 35.2+/-16.5 microg/g in patients and controls respectively; with variability 106.5%) were both higher than those of controls. However, only the iron concentration was significantly different (p<0.05).

Isotopic analogues as internal standards for quantitative analyses of drugs and metabolites by GC-MS--nonlinear calibration approaches

In order to achieve accurate quantitation of drugs and metabolites (analytes) in complex matrices, 2H- (and less commonly 13C-) labeled analogues of the analytes are now routinely adapted as the internal standards (IS) using linear calibration models to fit data generated by selected ion monitoring gas chromatography-mass spectrometry (GC-MS) protocols. In this study, the effects of cross-contribution (contribution of the IS to the intensity of the ion designated for the analyte and vice versa) on the linearity of the calibration data are examined. Nonlinear approaches that may address this problem are also studied. Two ion pairs (one with least and one with significant cross-contribution) from each of the following analyte/IS pairs are used as the exemplar systems for this study: butalbital/13C4-butalbital, butalbital/2H5-butalbital, secobarbital/13C4-secobarbital, and secobarbital/2H5-secobarbital. Analyte/IS ion intensity ratios of a series of standard solutions are correlated with the analyte/IS concentration ratios using one-point, multiple-point (unweighted and weighted) linear, and hyperbolic functions. The one-point calibration approach produces excellent calibration results in treating data derived from ion pairs with no significant cross contribution. In cases where significant cross-contribution exists, results derived from the one-point approach show, as expected, significant deviations at both ends of the concentration range. With the cross-contribution phenomenon accounted for, the hyperbolic calibration model is clearly more effective in fitting calibration data at both the lower and higher analyte concentration ends, thus significantly lowering the detection limit and extending the calibration range to a higher level. However, the calibration range cannot be extended indefinitely. At the low concentration end, noise-to-signal ratio and the cross-contribution of the IS to the intensity of the ion designated for the analyte, however insignificant, will incrementally reduce the quality of the observed ion intensity and intensity ratio data. At the high concentration end, detection saturation and the cross-contribution of the analyte to the intensity of the ion designated for the IS, however insignificant, will incrementally decrease the "slope" of the calibration curve. Thus, acceptable sensitivity (increase in analyte/IS ion-pair intensity ratio per unit increase in analyte concentration) of the calibration curve will become the limiting factor.

Adverse health effects among household waste collectors in Taiwan

Household waste collectors (HWCs) are potentially exposed to a variety of bioaerosols and toxic materials. Collection of household waste is also a job which requires repeated heavy physical activity such as lifting, carrying, pulling, and pushing. The object of this study was to assess whether there is an excess of adverse health outcomes among HWCs. The subjects were all current employees of the Household Waste Collection Department in the County of Kaohsiung, Taiwan. The survey questionnaire was completed by 533 HWCs and 320 office workers. Our data indicate that household waste collection presents a risk for the development of chronic respiratory symptoms (cough, phlegm, wheezing, and chronic bronchitis), musculoskeletal symptoms (low back pain and elbow/wrist pain), and injuries caused by sharp objects.

Triptolide and chemotherapy cooperate in tumor cell apoptosis. A role for the p53 pathway

Triptolide (PG490), a diterpene triepoxide, is a potent immunosuppressive agent extracted from the Chinese herb Tripterygium wilfordii. We have previously shown that triptolide blocks NF-kappaB activation and sensitizes tumor necrosis factor (TNF-alpha)-resistant tumor cell lines to TNF-alpha-induced apoptosis. We show here that triptolide enhances chemotherapy-induced apoptosis. In triptolide-treated cells, the expression of p53 increased but the transcriptional function of p53 was inhibited, and we observed a down-regulation of p21(waf1/cip1), a p53-responsive gene. The increase in levels of the p53 protein was mediated by enhanced translation of the p53 protein. Additionally, triptolide induced accumulation of cells in S phase and blocked doxorubicin-mediated accumulation of cells in G(2)/M and doxorubicin-mediated induction of p21. Our data suggest that triptolide, by blocking p21-mediated growth arrest, enhances apoptosis in tumor cells.

Aortic stenting on a type B aortic dissection with visceral and limb ischemia

Aortic dissection complicated with limb and visceral ischemia is a clinical dilemma since surgical intervention carries high risk of morbidity and mortality. The management is further complicated when renal perfusion is impaired and thus associated with severe renovascular hypertension. As catheterization techniques advanced over the past decade, percutaneous endovascular intervention provides a less invasive alternative for management of such cases. We report a case of chronic Stanford type B aortic dissection complicated with visceral and limb ischemia presenting with marked renovascular hypertension, which was successfully treated with percutaneous endovascular aortic stenting.

Control of idiopathic ventricular fibrillation by implantable cardioverter-defibrillator in a child who survived sudden death

Idiopathic ventricular fibrillation (VF) is extremely rare in children who have not previously undergone cardiac surgery. Patients resuscitated from idiopathic VF remain at risk for recurrence. The use of an implantable cardioverter-defibrillator (ICD) effectively prevents such recurrences. We report the case of a 12-year-old girl who had a history of recurrent syncope and had survived an episode of VF. Serial studies after prolonged but successful resuscitation, including echocardiography, an electrocardiogram (ECG), and coronary angiography failed to reveal abnormal cardiac structures responsible for VF. No abnormal conduction pathways or abnormal early or late after depolarization were found on electrophysiologic study. The ST segments of the 12-lead ECG remained normal after procainamide challenge. The patient underwent ICD implantation 2 weeks after admission and syncope did not recur during a follow-up of 14 months. This report emphasizes that idiopathic VF may be responsible for syncope in children. ICD therapy prevents the recurrence of idiopathic VF and the associated risk of sudden death.

Point mutation associated with X-linked dominant Charcot-Marie-Tooth disease impairs the P2 promoter activity of human connexin-32 gene

Many lines of evidence suggest that connexin-32 gap junction is involved in the exchange of information and metabolites in the peripheral nervous system. It has been shown that connexin-32 protein and mRNA are expressed in Schwann cells that function as myelinating cells of the peripheral nervous system. The physiological importance of connexin-32 gap junctions in regulating the normal function of myelinating Schwann cell is indicated by recent findings that X-linked dominant Charcot-Marie-Tooth disease, a hereditary peripheral neuropathy, is associated with the mutations of connexin-32 gene. Recently, we encountered a Taiwanese family affected with X-linked dominant Charcot-Marie-Tooth neuropathy. Therefore, we investigated the possible mutation in the coding and noncoding regions of the connexin-32 gene of affected members of this family. Our results suggest that a G-to-A transition at the position -215 (in relation to the transcription initiation site) of the nerve-specific P2 promoter region is associated with the pathogenesis of X-linked dominant Charcot-Marie-Tooth disease. Further experiments using the promoter assay indicate that G-to-A mutation at the position -215 greatly impairs the transcriptional activity of connexin-32 P2 promoter. These findings propose that a reduced expression of connexin-32 mRNA and protein in the myelin sheath could be responsible for the development of X-linked dominant Charcot-Marie-Tooth neuropathy.

Chemical derivatization and the selection of deuterated internal standard for quantitative determination--methamphetamine example

Use of an isotopic analogue of the analyte as the internal standard in a quantitative gas chromatography-mass spectrometry targeted-compound-analysis protocol is often hindered by the availability of an adequate number (typically three for the drug/metabolite and two for the isotopic analogue) of sufficiently high mass ions that can be attributed to each member of the pair and are sufficiently free of interference by the contribution from the other component of the pair, a phenomenon termed "cross-contribution". Methamphetamine (MA) is selected as the exemplar compound to examine the effectiveness in using different chemical derivatization routes to produce derivatized analyte-isotopic analogue pairs that can generate more favorable mass spectrometric data to meet this analytical requirement. Trimethylsilyl-, trichloroacetyl-, and pentafluoropropionyl-derivatization and MA-d5, MA-d8, and MA-d9 are studied. Data resulting from this study indicate that the number of ion pairs suitable for quantitation and the degree of cross-contribution of these ions vary significantly. These data empirically demonstrate that derivatization methods play a significant role in deciding which deuterated analogue of the analyte provides the most suitable ion pairs that cause the least cross-contribution. The most suitable internal standard varies with the derivatization route adapted for an analytical protocol.

Persistent myocardial ischemia after termination of dipyridamole-induced ventricular tachycardia by intravenous aminophylline: scintigraphic demonstration

Ventricular tachycardia is a rare complication of dipyridamole stress testing. We present a case in which dipyridamole induced symptomatic ventricular tachycardia. The patient, a 41-year-old man with a history of chest discomfort on exertion for 1 year, underwent dipyridamole thallium imaging. Sustained ventricular tachycardia occurred 1 minute and 40 seconds after completion of the dipyridamole infusion. Intravenous aminophylline (125 mg) was given immediately and the tachycardia was terminated. Two minutes later, thallium-201 was injected and subsequent myocardial imaging showed reversible perfusion defects in the inferior wall, septum, and apex. Coronary angiography revealed three-vessel disease. This case discloses that reversible perfusion defects can still be demonstrated on thallium scan in spite of injection of aminophylline, an antagonist of dipyridamole, before thallium administration.

Isolation of spermidine synthase gene (spsA) of Dictyostelium discoideum

The gene encoding spermidine synthase (spsA) was isolated from Dictyostelium discoideum using the technique of insertional mutagenesis. Northern blot analysis showed that the spsA mRNA is expressed maximally during the vegetative stage and decreases gradually during the 24 h of development. Sequencing of the genomic DNA and a full-length cDNA clone indicated the presence of one intron in a gene coding for a predicted protein (SpsA) with 284 amino acids. The sequence is highly conserved, with amino acid identities compared to spermidine synthases of humans, 59.5%, to mouse, 61.3%, and to yeast, 58.1%. A null mutant of the spsA gene is unable to grow in the absence of exogenous spermidine. Development of spsA null cells grown in the absence of spermidine produced fruiting bodies that have abnormally short stalks.

A novel adenylyl cyclase detected in rapidly developing mutants of Dictyostelium

Disruption of either the RDEA or REGA genes leads to rapid development in Dictyostelium. The RDEA gene product displays homology to certain H2-type phosphotransferases, while REGA encodes a cAMP phosphodiesterase with an associated response regulator. It has been proposed that RDEA activates REGA in a multistep phosphorelay. To test this proposal, we examined cAMP accumulation in rdeA and regA null mutants and found that these mutants show a pronounced accumulation of cAMP at the vegetative stage that is not observed in wild-type cells. This accumulation was due to a novel adenylyl cyclase and not to the known Dictyostelium adenylyl cyclases, aggregation stage adenylyl cyclase (ACA) or germination stage adenylyl cyclase (ACG), since it occurred in an acaA/rdeA double mutant and, unlike ACG, was inhibited by high osmolarity. The novel adenylyl cyclase was not regulated by G-proteins and was relatively insensitive to stimulation by Mn2+ ions. Addition of the cAMP phosphodiesterase inhibitor, 3-isobutyl-1-methylxanthine (IBMX) permitted detection of the novel adenylyl cyclase activity in lysates of an acaA/acgA double mutant. The fact that disruption of the RDEA gene as well as inhibition of the REGA-phosphodiesterase by IBMX permitted detection of the novel AC activity supports the hypothesis that RDEA activates REGA.

Production and activity of spore differentiation factors (SDFs) in Dictyostelium

SDF-1 and SDF-2 are peptides that promote terminal spore differentiation under submerged conditions. The present study shows that they accumulate differentially and are released during the development of wild-type cells and can promote spore formation in cells disaggregated from wild-type culminants. SDF-1 accumulates during the slug stage and is released in a single burst at the onset of culmination while SDF-2 accumulates during early culmination and is released in a single burst from mid-culminants. The effects of SDF-1 and SDF-2 on stalk cell formation in cell monolayers were investigated. SDF-1 by itself induces stalk cell formation in some strains and also synergizes with the stalk-cell-inducing factor, DIF-1. cAMP has an inhibitory effect on stalk cell formation when either DIF-1 or SDF-1 are present on their own but is almost not inhibitory when both are present. SDF-2 alone does not induce stalk cell formation and appears to inhibit the response to DIF-1. At the same time, it increases the extent of vacuolization of the stalk cells that are produced. We propose that the release of SDF-1 and then of SDF-2 may mark irreversible steps in the developmental programme associated, respectively, with culmination and spore maturation.

Mutational analysis of Caenorhabditis elegans CED-4

Much of our knowledge concerning the genetics that regulate cell death has come from the studies of cell death during the development of the nematode Caenorhabditis elegans. Of the 14 genes identified as components of nematode cell death pathways, two genes, ced-3 and ced-4, are required to promote cell death and a third, ced-9, blocks cell death. Recent studies show CED-4 to be an activator of CED-3 and CED-9 to be an inhibitor of CED-4. Two published sequence alignments suggest that CED-4 contains a death effector domain (DED), a protein sequence motif present in other death signaling proteins like Fadd and Flice; one study suggests a DED sequence similarity near the N-terminus while the other found sequence similarity near the C-terminus of CED-4. Using mutational analysis we have tested the functional significance of the conserved residues found within the putative DEDs of CED-4. Mutations in two conserved residues within the putative N-terminal DED of CED-4 affected its function, while mutations in the conserved residues within the putative C-terminal DED had no effect on CED-4 function. Our results do not support the presence of a DED in the C-terminus of CED-4 and suggest a potential role for the N-terminus in CED-4 function, possibly as a DED or as a CARD (caspase recruitment domain). We also found that CED-9 associated with all the CED-4 mutants and inhibited the activity of all the active-CED-4 mutants.

Evidence that the RdeA protein is a component of a multistep phosphorelay modulating rate of development in Dictyostelium

We have isolated an insertional mutant of Dictyostelium discoideum that aggregated rapidly and formed spores and stalk cells within 14 h of development instead of the normal 24 h. We have shown by parasexual genetics that the insertion is in the rdeA locus and have cloned the gene. It encodes a predicted 28 kDa protein (RdeA) that is enriched in charged residues and is very hydrophilic. Constructs with the DNA for the c-Myc epitope or for the green fluorescent protein indicate that RdeA is not compartmentalized. RdeA displays homology around a histidine residue at amino acid 65 with members of the H2 module family of phosphotransferases that participate in multistep phosphoryl relays. Replacement of this histidine rendered the protein inactive. The mutant is complemented by transformation with the Ypd1 gene of Saccharomyces cerevisiae, itself an H2 module protein. We propose that RdeA is part of a multistep phosphorelay system that modulates the rate of development.

An intersection of the cAMP/PKA and two-component signal transduction systems in Dictyostelium

Terminal differentiation of both stalk and spore cells in Dictyostelium can be triggered by activation of cAMP-dependent protein kinase (PKA). A screen for mutants where stalk and spore cells mature in isolation produced three genes which may act as negative regulators of PKA: rdeC (encoding the PKA regulatory subunit), regA and rdeA. The biochemical properties of RegA were studied in detail. One domain is a cAMP phosphodiesterase (Km approximately 5 microM); the other is homologous to response regulators (RRs) of two-component signal transduction systems. It can accept phosphate from acetyl phosphate in a reaction typical of RRs, with transfer dependent on Asp212, the predicted phosphoacceptor. RegA phosphodiesterase activity is stimulated up to 8-fold by the phosphodonor phosphoramidate, with stimulation again dependent on Asp212. This indicates that phosphorylation of the RR domain activates the phosphodiesterase domain. Overexpression of the RR domain in wild-type cells phenocopies a regA null. We interpret this dominant-negative effect as due to a diversion of the normal flow of phosphates from RegA, thus preventing its activation. Mutation of rdeA is known to produce elevated cAMP levels. We propose that cAMP breakdown is controlled by a phosphorelay system which activates RegA, and may include RdeA. Cell maturation should be triggered when this system is inhibited.

Three-dimensional PET emission scan registration and transmission scan synthesis

The duration of a positron emission tomography (PET) imaging scan can be reduced if the transmission scan of one patient which is used for emission correction can be synthesized by using the reference transmission scan of another patient. In this paper, we propose a new intersubjects PET emission scan registration method and PET transmission synthesis method by using the boundary information of the body or brain scan of the PET emission scans. The PET emission scans have poor image quality and different intensity statistics so that we preprocess the emission scans to have similar histogram and then apply the point distribution model (PDM) [15] to extract the contours of the emission scan. The extracted boundary contour of every slice is used to reconstruct the three-dimensional (3-D) surface of the reference set and the target set. Our registration is 3-D surface-based which uses the normal flow method [17] to find the correspondence vector field between two 3-D reconstructed surfaces. Since it is difficult to analyze internal organ using the PET emission scan imaging without correction, we assume that the deformation of internal organ is homogeneous. With the corresponding vector field between the two emission scans and the transmission scan of the reference set, we can synthesize the transmission scan of the target set.

Production of chitinase from shellfish waste by Pseudomonas aeruginosa K-187

The production of chitinolytic enzyme by Pseudomonas aeruginosa K-187, using shrimp and crab shell powder (SCSP) as the carbon source, was studied. It was observed that chemically treated SCSP induced a significant increase of enzyme production, as compared with untreated SCSP. Spent HCl and NaOH from the chitin production industry was used to process SCSP. Various strategies of SCSP processing are examined and compared in terms of chitinolytic enzyme production. A three-and-one-half-fold increase of enzyme production (0.68 U/ml to 2.4 U/ml) was attained using HCl/NaOH treated SCSP. The microorganism (K-187) was isolated from soil in Taiwan and has been characterized and reported in a previous paper.

Purification and characterization of two bifunctional chitinases/lysozymes extracellularly produced by Pseudomonas aeruginosa K-187 in a shrimp and crab shell powder medium

Two extracellular chitinases (FI and FII) were purified from the culture supernatant of Pseudomonas aeruginosa K-187. The molecular weights of FI and FII were 30,000 and 32,000, respectively, by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and 60,000 and 30,000, respectively, by gel filtration. The pIs for FI and FII were 5.2 and 4.8, respectively. The optimum pH, optimum temperature, pH stability, and thermal stability of FI were pH 8, 50 degrees C, pH 6 to 9, and 50 degrees C; those of FII were pH 7, 40 degrees C, pH 5 to 10, and 60 degrees C. The activities of both enzymes were activated by Cu2+; strongly inhibited by Mn2+, Mg2+, and Zn2+; and completely inhibited by glutathione, dithiothreitol, and 2-mercaptoethanol. Both chitinases showed lysozyme activity. The purified enzymes had antibacterial and cell lysis activities with many kinds of bacteria. This is the first report of a bifunctional chitinase/lysozyme from a prokaryote.

Identification of the cell fate gene stalky in Dictyostelium

Using insertional mutagenesis, we have isolated a "stalky" mutant in which cells destined to become spores end up as stalk cells. Similar mutants were previously observed after chemical mutagenesis, but the affected gene could not be isolated. Our mutant, like the previous ones, is in stkA. Its defect is cell-autonomous and not overcome by overexpressing cAMP-dependent protein kinase. stkA is strongly expressed in the prespore region of aggregates but not in the anterior prestalk zone. The mutant expresses normal levels of prespore-cell transcripts but fails to produce the spore transcript spiA. stkA encodes a predicted 99 kDa protein (STKA) with two putative C4 zinc fingers, one of which is a GATA-type finger, indicating that it may be a transcription factor. This conclusion is supported by localization of STKA in the nucleus.

Detection of k-ras point mutations in codons 12 and 13 in non-small cell lung cancers

Point mutations of the K-ras gene have been reported in a wide variety of human tumors. By using polymerase chain reaction followed by direct DNA sequencing, we screened for point mutations at codons 12 and 13 of the K-ras gene in specimens obtained from fresh frozen tumors in 38 patients with non-small cell lung cancers. Point mutations were detected in two of 38 (5.3%) resected non-small cell lung cancers. Both of them were G to T transversions. One patient was found to have a K-ras codon 13 point mutation (GGC to TGC, gly to cys), while the other had a codon 12 point mutation (GGT to GTT, gly to val). Based on the limited numbers in this study, we found that the frequency of K-ras point mutations in codons 12 and 13 among Asian patients with lung adenocarcinomas was lower than that detected among Caucasian patients.

Evidence for transcriptional modulation but not acid phosphatase expression during programmed cell death in the colonial tunicate Botryllus schlosseri

Botryllus schlosseri is a clonally modular ascidian in which asexually derived adults (zooids) exhibit developmental synchrony. At the conclusion of the blastogenic (asexual) cycle every 5 days at 21 degrees C, all zooids within a colony die simultaneously in 24 hours and are replaced by a new asexual generation of zooids. This cyclical process, called takeover, involves the selective destruction of the zooid's visceral tissues which include the pharynx, esophagus, stomach, intestine, endostyle, neural complex and heart, whereas bud tissues and mesenchymal components (muscle and blood cells) remain unaffected. Ultrastructural analysis indicates that the most prevalent form of cell death occurs by apoptosis, although necrotic changes are also observed in several tissues (i.e., stomach and intestine). Blood-derived macrophages and neighboring cells subsequently engulf visceral tissues, reducing the zooid to the size of a small vesicle. Here, we have tested the possibility that acid phosphatase, a hydrolase whose presence is associated with cell death in several invertebrate systems, could account for some of the regressive changes observed during takeover. Our observations indicate that acid phosphatase (AP) activity was selectively localized in the gut of parent zooids during the growth phase of the cycle, with the stomach exhibiting the most intense histochemical staining on tissue sections. As zooid regression progressed during takeover, stomach AP staining gradually disappeared. Other visceral tissues never became AP-positive. Therefore, this hydrolase appears to play a minimal role in zooid death. In order to characterize genes whose expression pattern was selectively altered during takeover, we have carried out differential mRNA display analysis. We report on two genes, 790.3 and 790.4, that are down- and upregulated, respectively, during this process. Collectively, these findings indicate that the takeover phase of blastogenesis in Botryllus involves modulated gene expression.

Surgical management of the buried penis

BACKGROUND

Buried penis is a congenital abnormality in which the phallus is concealed within the surface of prepubic skin. It is probably more common than is generally recognized. The objective was to describe the pathophysiology, and search for the best management of this disease.

METHODS

Over a period of 6 years, a total of 31 cases receiving surgery for buried penis at this hospital were analyzed. According to their major pathophysiology, patients were divided into three groups: in the first, the major mechanism was poor skin suspension; in the second, prominent suprapubic fat pad was the major cause. In the third group, the dartos fascia was abnormally thickened and attached to the penile shaft. Different surgical techniques were applied in the different groups.

RESULTS

All 15 children in the first group had satisfactory results after penile skin fixation. In the second group, nine children underwent adjunctive lipectomy but only five had satisfactory results. Seven patients in the third group needed degloving of the penis and the three cases who underwent preputial unfurling had severe lymphedema of the inner preputial layer. One of them received revision. The end results were good in the other six patients after long-term follow up.

CONCLUSIONS

The buried penis occurs in a spectrum. Although, there are three major pathophysiology mechanisms, most of the patients had a combination. Surgical management should be individualized, and results are usually satisfactory. For the obese patient, weight loss is important. Preputial unfurling and using inner preputial layer to cover the defect should be avoided because of severe postoperative lymphedema.

Antenatal diagnosis and early surgery for choledochal cyst: a report of two cases

Since the advent of routine antenatal sonography to detect fetal abnormalities, two cases of choledochal cyst have been found prenatally in our hospital. The first presented when a choledochal cyst was demonstrated at 31 weeks of gestation, and a firm diagnosis established within 2 days of birth. Technetium 99m disofenin (DISIDA) cholescintigram revealed delayed visualization of the small bowel. The second case was found by ultrasound examination at 21 weeks of gestation to have a choledochal cyst, and diagnosis was confirmed within 3 days of birth. DISIDA scintigram demonstrated complete obstruction of the extrahepatic biliary tree. Both infants received early excision of the cyst at the ages of three and four days respectively. The postoperative course was quite smooth, and there were no abnormal symptoms after follow up of four and two years, respectively. Neonates with distal common bile duct obstruction in association with presumed choledochal cyst should have prompt surgical exploration, and early excision of the cyst is a safe procedure in the newborn.

Trapping developmental promoters in Dictyostelium

Recently an insertional mutagenesis procedure has been developed to permit cloning of genes affected in developmental mutants of Dictyostelium discoideum (Kuspa and Loomis, Proc. Natl. Acad. Sci. USA 89, 8803-8807, 1992). In this procedure a plasmid bearing the URA (pyr5-6) gene is linearized with a restriction enzyme and electroporated into URA- amoebae (auxotrophic for uracil) together with the corresponding restriction enzyme. Transformants that can grow without uracil are screened for developmental defects resulting from insertion of the plasmid into a gene of developmental importance. We have modified this procedure to permit characterization of the promoters and structural sequences of genes that would be missed by the standard procedure because their disruption produces no obvious phenotype. Constructs carrying a promoter-less Escherichia coli lacZ gene were designed so that expression of lacZ requires insertion into an active host transcription unit. By screening restriction enzyme-generated transformants we have isolated several strains in which lacZ is under the control of a developmentally activated promoter and have cloned the 5' flanking DNA adjacent to the insertion site. Sequencing the junction between plasmid and host genome has confirmed in-frame fusion with the lacZ gene, and reintroduction of the cloned plasmids into parental cells has shown that the cloned sequences do actually contain the relevant promoters. This procedure should give ready access to a wide range of developmental promoters without the need for prior identification of the developmental genes involved.

Jejunoileal atresia in neonates

BACKGROUND

Jejunoileal atresia is the most common intestinal atresia and the most frequent cause of neonatal intestinal obstruction. The prognosis depends on several important factors. The patients reported were collected for evaluation of the factors contributing to their prognoses.

METHODS

In the ten-year period from October 1982 to October 1992, all jejunoileal atresia patients who received treatment in this hospital were entered in this study. Possible factors contributing to prognosis, such as prematurity, low birth weight, apple peel atresia, anastomotic leakage, sepsis, short bowel syndrome were evaluated using Mann-Whitney U-test.

RESULTS

Twenty-four patients of jejunoileal atresia had been managed in our hospital in 10 years period. Their ages ranged from one to thirteen days old (mean 3.9 days). The numbers and types of atresia were as follow: type I (n = 4), type II (n = 4), type IIIa (n = 10), type IIIb (n = 5), type IV (n = 1). All patients received surgical correction. Nine complications were found in eight patients, which included four anastomotic leakage, three wound infections and two intestinal obstructions. There were three mortalities from sepsis. Total parenteral nutrition was applied to 14 patients (58.3%). The mean hospital stay was 45.1 days, and the survival rate was 87.5%. Low birth weight and anastomotic leakage contributed to prolonged hospital stays (p < 0.05).

CONCLUSIONS

Jejunoileal atresia is a common neonatal surgical condition. The prognosis is generally good, except when a patient presented with factors, such as, low birth weight or anastomotic leakage, which prolonged hospital stays. Moreover, sepsis is the only important factor contributing to mortality.