Electronic minibands in complex basis superlattices: a numerically stable calculation

A numerically stable method for accurately determining the energy minibands of superlattices with arbitrary numbers of layers per cell is presented. Using a graph model with tangent and secant functions, we derive a set of concise and closed-form miniband edge equations for determining the miniband structure using topology theory. With the present method, it is not necessary to calculate the cosine of the Bloch phase, which may show a numerical overflow in calculation. Numerical results show that use of the miniband edge equations has better numerical stability than traditional methods in calculating the minibands of complex basis superlattices.

Perspectives on health effects of electric and magnetic fields

Some epidemiological studies have fostered concern about cancers caused by electric and magnetic fields associated with distribution and use of electric power. At present, there is no scientific consensus as to which factors, the electric field and/or magnetic field, are biologically important. Similarly, there is no clear indication whether higher field levels are of greater risk than lower level fields. The complex scientific issues attending health effects of power-frequency electric and magnetic fields would be most effectively resolved through interdisciplinary research involving investigators from biological, medical and engineering research communities. A critical need, at present, is a significant increase in federal funding for research on interaction mechanisms and animal studies, while maintaining efforts in epidemiology but with greater emphasis on confounding factors and known cancer-causing agents.

Brain energy stores in C57BL/6 mice after C. parvum injection

Activation of the immune system has been associated with the development of fatigue of unknown cause. We were interested in brain energy stores (e.g., phosphocreatine (PCr) and creatine kinase) after immune activation to investigate whether this system was altered. In this model, fatigue (defined as > 50% reduction in spontaneous running) was induced in C57BL/6 mice after a single injection of Corynebacterium parvum antigen. Maximal fatigue (about 86% reduction on day 10 post injection) was associated with reduced (about 29%) brain PCr/gamma-ATP and increased creatine kinase levels (approximately 31%), suggesting an active process of brain ATP depletion and replenishment. These findings need to be further delineated to establish the relationship between immune activation, reduced brain energy pools and fatigue.

P5644Hypoglycemic episodes increase the risk of ventricular arrhythmias and sudden cardiac arrest in patients with type 2 diabetes - a nationwide cohort study

Background

Hypoglycemic episode (HE) increases the risk of cardiovascular mortality. The impact of HE on the risk of sudden death remains unclear. We hypothesized that HE increases the risks of ventricular arrhythmia (VA) and sudden cardiac arrest (SCA), and that anti-diabetic agents (ADAs) causing hypoglycemia also increase the risks of VA and SCA.

Methods

Patients aged ≥20 years with newly diagnosed diabetes were identified from the Taiwan National Insurance Database. HE was defined as the presentation of hypoglycemic coma or specified/unspecified hypoglycemia. For control group, we included diabetic patients without HE, and they were frequency-matched to the HE group at a 4:1 ratio. The primary outcome was the occurrence of any event of VA (including ventricular tachycardia and fibrillation) and SCA during the defined follow-up periods. Multivariate Cox hazards regression model was used to evaluate the hazard ratio (HR) for VA or SCA.

Results

A total of 54,303 diabetic patients were screened with 1,037 of them in the HE group, and 4,148 in the control group. During a mean follow-up period of 3.3±2.5 years, 29 VA/SCA events had occurred. Compared to the control group, the HE group had a higher incidence of VA/SCA (adjusted HR: 2.42, p=0.04). Diabetic patients medicated with insulin for glycemic control increased the risk of VA/SCA compared to those without insulin (adjusted HR: 3.05, p=0.01).

Kaplan-Meier survival curves

Conclusions

HEs in patients with diabetes increased the risks of VA and SCA compared to those without. Their use of insulin also independently increased the risk of VA/SCA.

Brachial plexus neuropathy associated with scrub typhus: report of a case

We report on a 20-year-old man who had scrub typhus with the unusual neurologic complication of brachial plexus neuropathy. The clinical features of fever, headache, pneumonitis, eschar, high Weil-Felix OX-K agglutination and Rickettsia tsutsugamushi immunofluorescence titers confirmed the diagnosis of scrub typhus. Brachial plexus neuropathy was proven by an electrophysiologic examination. He had a nearly complete recovery after adequate medical treatment.

Detection of circulating tumor cells in venous blood of nasopharyngeal carcinoma patients by nested reverse transcriptase-polymerase chain reaction

Nasopharyngeal carcinoma (NPC) is a radiosensitive tumor. Because of recent advances in radiation oncology, distant metastasis has become the predominant failure site after adequate radiotherapy. The purpose of this study is to establish a nested reverse transcriptase-polymerase chain reaction (RT-PCR) system and to evaluate the potential of cytokeratin 19 (CK-19) mRNA as a target for detecting micrometastasis in the blood of NPC patients. Venous blood samples from 40 patients with biopsy-proven NPC (25 previously untreated and 15 after radiotherapy) and 20 healthy volunteers were tested. We divided the 40 patients into 4 groups: cured, early stage, advanced stage, and metastasized, according to results of clinical staging work-up. Under our nested RT-PCR experimental conditions, 2 of 8 early stage patients (25.0%), 6 of 15 advanced stage patients (40%), and 6 of 8 patients with distant metastasis (75%) had CK-19 positive cells in peripheral blood (P = 0.11). No CK-19 positive cells were detected in 9 "cured" patients and 20 healthy volunteers. Our data indicated that the positive detection rate for CK-19 mRNA in peripheral blood increased as the clinical stage of disease increased, but the difference did not reach statistical significance. Longer follow-up is needed to assess the significance of CK-19 mRNA in blood, as well as its relation to subsequent metastasis and prognosis of NPC.

QT prolongation and development of torsades de pointes with the concomitant administration of oral erythromycin base and quinidine

Torsades de pointes is a polymorphic ventricular tachycardia characterized by marked QT prolongation on the electrocardiogram. It can be induced by both antiarrhythmic and nonantiarrhythmic drugs, such as quinidine and erythromycin. No extensive literature documents an interaction between quinidine and erythromycin when the agents are administered orally. A 95-year-old man received oral quinidine and erythromycin for the treatment of atrial fibrillation and community-acquired pneumonia. He developed torsades de pointes and subsequently cardiac arrest. Since erythromycin and quinidine are known to cause arrhythmias individually, caution and close monitoring are necessary when the drugs are administered concomitantly.

Non steroidal anti-inflammatory drug-based pain control for minimally invasive direct coronary artery bypass surgery

Minimally invasive direct coronary artery bypass (MIDCAB) surgery has become an attractive alternative technique to treat coronary artery insufficiency. Changes in surgical and anesthesia techniques have led to reduced pulmonary morbidity associated with the operation. Early extubation is typically expected. However, postoperative pain management becomes even more important with early extubation. We describe our technique of a NSAID-based protocol with indomethicin and Torodal that has been safe and effective in over 175 patients following MIDCAB.

Concomitant chemoradiotherapy for advanced head and neck cancer

Head and neck cancer is mostly curable in the early stages by either surgery or radiotherapy alone, but the control rate for advanced stages is low, even with combined surgery and postoperative radiotherapy. From September, 1990, to January, 1992, 35 patients with locoregionally advanced head and neck cancers were entered in a prospective study of concomitant chemoradiotherapy. Thirty-three completed the treatment. There were 29 males and four females with a median age of 53 years. All except one patient were in stage IV. Radiotherapy was delivered using a telecobalt unit and by conventional fractionation (1.8 Gy/fraction, 5 fractions/wk). Chemotherapy with cisplatin (10 mg/m2/day, daily, days 1-5) and 5-FU (500 mg/m2/day continuously infused for five days) was given concurrently during the first and fifth weeks of radiation. Twenty-four among 31 eligible patients achieved complete response (77.4%) and the other seven (22.6%) partial response, resulting in a 100% response rate. The toxicities experienced were increased compared with those caused by radiotherapy alone. The most common side effects were gastrointestinal and hematologic toxicities but the whole treatment was well tolerated. The two-year actuarial survival rate is 45%. We found the primary origin and overall treatment time to affect survival significantly. The survival rate for tumors arising from the nasopharynx or paranasal sinus is better than for those arising from other regions of the head and neck. The shorter treatment times (within eight weeks) had a better survival rate. Our preliminary experience suggests that concomitant chemoradiotherapy is both feasible and effective for head and neck cancer. The optimal scheduling and dosage of concomitant chemoradiotherapy should be further researched.

Endogenous Candida endophthalmitis: a case report

We experienced a 63-year-old male with a typical finding of endogenous Candida endophthalmitis. Candida albicans was cultured from the vitreous tapping. The patient received oral fluconazole treatment and the symptom improved. In this report, the clinical manifestations of endogenous Candida endophthalmitis and the experience of fluconazole treatment were reported.

Axillary F-loop latency of ulnar nerve in normal young adults

F waves were studied with stimulation of the ulnar nerve in normal subjects (25 men and 15 women, with an average age of 26.5 years) using an EMG machine that permits the simultaneous display of 8 sweeps. The axillary F-loop latency (AFLL), defined at the conduction time between the axilla (25cm from the sternal notch) and the spinal cord, was 9.17 +/- 0.81msec when 8 F responses were measured but was 8.57 +/- 1.00msec when 40 F responses were used. Data from men and women showed no significant statistical difference. The mean plus 2 standard deviations were 10.8 and 10.6msec for 8 and 40 responses, respectively. On the basis of these findings, an AFLL longer than 11msec should be considered abnormal in the young adult. Four measures repeated at weekly intervals showed no significant difference from week to week, indicating that the technique can be consistently and reliably applied at different times. The average duration of the F complex was 15.78 +/- 2.55msec and was about 80% of the average duration of the M wave.

Postoperative radiotherapy for glioblastoma multiforme

Between July 1983 and December 1990, 39 patients with pathologically documented glioblastoma multiforme were treated with radiotherapy after biopsy (5 patients) or resection (34 patients). There were 30 males and 9 females ranging in age from 9 to 68 years (median 52). All but one of the 39 patients were treated with 10 MV photons. Whole brain irradiation was delivered through lateral parallel opposed fields for the first 40 Gy, followed by reduced portals to boost the tumor bearing area. The range of tumor dose was 58 to 70 Gy, with a median dose of 64 Gy (33 patients). Treatment was executed at 2 Gy per fraction, 5 days per week for all patients except 2 who received 1.8 Gy per fraction. Eight patients underwent reoperation at least once after radiotherapy due to suspicion of recurrence of the disease. No patients were lost to follow-up: 35 patients had died and 4 were still alive. The median survival time was 11.8 months. The 1- and 2-year survival rates were 49% and 12% respectively. A prognostic factor analysis shows that treatment response and the pre-irradiation Karnofsky status were statistically significant variables influencing survival. The median survival was 28.7 months for patients with complete response, compared with 9.8 months for those with partial response or stable disease (p = 0.002). The median survivals were 13.5 and 9.0 months in high (> or = 70%) and low Karnofsky performance scale (p = 0.04). Smaller tumors, a larger extent of resection, reoperation and younger age were favorable factors with borderline significance.(ABSTRACT TRUNCATED AT 250 WORDS)

Fournier's gangrene: experience of four cases

Fournier's gangrene is an acute gangrenous inflammation of the male genitalia. In an 18-month period, four patients with Fournier's gangrene were treated at our hospital. Their ages ranged from 39 to 74 years (average 55.2). The presenting symptoms and signs included pain, swelling and necrosis of the scrotum and perineum, fever and jaundice were also noted. Three patients with the predisposing factor of urinary tract infection or perianal abscess recovered after surgical debridement and antibiotics treatment. Their hospital stay ranged between 13 and 50 days. One patient with diabetes, presenting severe septic shock at arrival, died one day after debridement. From the experience of our cases and review of the literature, early surgical debridement and antibiotics are mandatory for the treatment of Fournier's gangrene.

[Production and characterization of monoclonal antibody against colon cancer associated antigen in Chinese]

Although many monoclonal antibodies have been made in human colon cancer, none of them are from the Chinese species. Recently, a colon cancer cell line CC-M2 established from a Chinese patient has been completely characterized and used as immunogen to produce monoclonal antibodies. Monoclonal antibodies were produced by standard hybridoma technique. The fusion rate was 95.8%. An isotype IgG1 of high proliferation named as Sam-2 was used in this study. The titers were measured around 10(4). Further studies on MoAb Sam-2 through indirect immunofluorescent and immunoperoxidase tests revealed its good specificity and sensitivity in colorectal cancer tissue. In CEA study, the result indicated that Sam-2 may react on a non-CEA related antigen. For further clinical application, the antigen was identified as a glycoprotein by chemical resistant test. In preliminary studies using sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting techniques, Sam-2 could recognize two closed antigens or a dimer antigen with molecular weight 25.2 and 27 Kd respectively.

Mars Methane Sources in Northwestern Gale Crater Inferred From Back Trajectory Modeling

During its first seven years of operation, the Sample Analysis at Mars Tunable Laser Spectrometer (TLS) on board the Curiosity rover has detected seven methane spikes above a low background abundance in Gale crater. The methane spikes are likely sourced by surface emission within or around Gale crater. Here, we use inverse Lagrangian modeling techniques to identify upstream emission regions on the Martian surface for these methane spikes at an unprecedented spatial resolution. Inside Gale crater, the northwestern crater floor casts the strongest influence on the detections. Outside Gale crater, the upstream regions common to all the methane spikes extend toward the north. The contrasting results from two consecutive TLS methane measurements performed on the same sol point to an active emission site to the west or the southwest of the Curiosity rover on the northwestern crater floor. The observed spike magnitude and frequency also favor emission sites on the northwestern crater floor, unless there are fast methane removal mechanisms at work, or either the methane spikes of TLS or the non-detections of ExoMars Trace Gas Orbiter cannot be trusted.