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PubMed2004

Midband solitons in nonlinear photonic crystal resonators.

We investigate cavity solitons in nonlinear photonic crystal resonators, i.e., in the nonlinear resonators with the refractive index periodically modulated in the transverse direction. We study several families of the cavity solitons: (1) "normal," and (2) "staggered" solitons, similar to those in conservative nonlinear photonic crystals; (3) "midband" solitons, predicted recently in dissipative nonlinear photonic crystals [Phys. Rev. Lett. 91, 053901 (2003)]]; and (4) "double head" cavity solitons not reported before. We investigate the solitons by (1) numerically solving the full microscopic model explicitly accounting for the small scale refractive index modulation, and (2) adopting a "mean field" approximation, e.g., eliminating the small scale refractive index modulation.

Journal Article↗
PubMed2006

Focusing concave lens using photonic crystals with magnetic materials.

The guided modes lying in the upper gap-edge band in the photonic band structure of photonic crystals have negative values of refractive index. This feature generates many interesting optical phenomena, and some spectacular photonic devices such as focusing slabs have been developed. We report the design of a photonic-crystal, planoconcave lens for focusing incident parallel light, and theoretically analyze the chromatic aberrations for TM and TE modes. In addition to dielectric photonic crystals, the chromatic aberration of a magnetic photonic-crystal planoconcave lens was investigated because the magnetic permeability may also contribute to the periodic index contrast in photonic crystals, especially at long wavelengths. A significant difference was found in the chromatic aberration for a TM mode propagating in a dielectric than in a magnetic photonic-crystal planoconcave lens.

Journal Article↗
PubMed1979

Effects of smoking and inhalation of carbon monoxide on systolic time intervals and blood pressure. Differences between two types of cigarettes and a cigar.

The effects of smoking and inhalation of carbon monoxide on the systolic time intervals and blood pressure were examined in ten healthy smokers with a mean age of 24.3 years. Each subject smoked a low-nicotine cigarette with a ventilated filter (0.1 mg nicotine, 1.1 vol percent CO), and a high-nicotine plain cigarette (2.6 mg nicotine, 4.5 vol percent CO), as well as a cigar in random sequence and in a standardized way. Cigar smoke was not inhaled. The product heart rate x blood pressure was increased and the left ventricular ejection time index (LVETc) prolonged following smoking the high-nicotine cigarette, whereas changes after smoking the low-nicotine cigarette and the cigar were not as pronounced. These changes are presumably caused by nicotine-induced catecholamine release. Inhalation of CO did not affect cardiac performance acutely as shown by unchanged systolic time intervals. When a high-nicotine cigarette was smoked after the subject received a beta blocker, a significant prolongation of the pre-ejection period index (PEPc) occurred as a result of the increased afterload. Thus, the effects of catecholamines on parameters of myocardial contractility (PEPc, PEP/LVET) were presumably offset by the increased afterload. We conclude that the acute hemodynamic changes of smoking in healthy subjects depend upon the amount of nicotine absorbed.

Adult↗
PubMed2002

[The change of hemodynamics index in acute period of severe combined injury].

Clinical significance and prognostical informativity of the hemodynamics indexes in an acute period of traumatic disease (TD) in severe combined thoracoabdominal trauma (SCTAT) were studied. The cardiac pump function, tone of vessels, their resistance, venous return were estimated. The pronounced and stable disorders of the hemodynamics indexes in injured persons with SCTAT were noted, their degree depended on the trauma severity, which had determined the TD outcome.

Abdominal Injuries↗
PubMed1998

Effects of verapamil on indexes of heart rate variability after acute myocardial infarction.

In patients with previous myocardial infarction (MI), depressed heart rate variability (HRV) may reflect a reduction in vagal activity and lead to cardiac electrical instability. Interventions designed to increase HRV may be of clinical interest. Data on the effects of calcium antagonists on HRV in post-MI patients are very limited. The aim of our study was to assess the effects of verapamil on HRV and on the sympathovagal balance after MI. Fifty consecutive patients with a first MI, stable sinus rhythm, and left ventricular ejection fraction >0.40 were studied. Each patient underwent two 24-hour Holter recordings, 1 at baseline and another after 4 days of treatment with verapamil retard (180 mg 2 times daily). Time and frequency domain parameters of HRV were analyzed. All time domain measurements increased significantly after verapamil: the standard deviation of all NN intervals (SDNN) from 87.1 +/- 31.4 to 98.1 +/- 30.3 ms (p <0.05) and the log-transformed percentage of pairs of adjacent NN intervals that differ >50 ms (pNN50) from 0.57 +/- 0.42 to 0.76 +/- 0.45 (p <0.01). The standard deviation of the averages of RR interevals (SDANN) (75.9 +/- 30.1 vs 86.3 +/- 29.4 ms, p <0.05), root-mean-square of successive differences between RR intervals (rMSSD) (23.0 +/- 11.7 and 28.1 +/- 13.1 ms, p <0.01), and the triangular HRV index (28.3 +/- 9.6 vs 23.4 +/- 8.6, p <0.001) also increased. A significant inverse correlation was found between improvement in HRV indexes induced by verapamil and baseline values. Spectral analysis showed a significant increase in high-frequency power of 58.5% without changes in low and very low components. With normalized units, significant reductions in low-frequency power and low- to high-frequency ratio were observed. Diabetic patients did not show any significant changes in HRV on administration of verapamil. These findings indicate that verapamil, administered during the subacute phase of MI, improves both global and short-period indexes of HRV and induces a shift in the sympathetic-parasympathetic interaction toward vagal predominance. This effect may contribute to an explanation of the beneficial effects of verapamil that have been reported in post-MI patients.

Adult↗
PubMed2004

Work-related outcomes after a myocardial infarction.

STUDY OBJECTIVE: To evaluate work-related outcomes of patients at 7 months after a myocardial infarction and to identify patient, disease, and intervention characteristics associated with these outcomes. DESIGN: Cross-sectional survey analysis. SETTING: Large Midwestern academic health system. PATIENTS: Eighty-nine patients with the discharge diagnosis of acute myocardial infarction during a 1-year index period. INTERVENTION: Work performance questionnaire administered by telephone, and medical record review. MEASUREMENTS AND MAIN RESULTS: Seven months after discharge, 232 patients were interviewed by telephone to determine work status before and after myocardial infarction, work-related outcomes (absenteeism and perceived work performance, assessed by the Work Performance Scale [WPS] of the Functional Status Questionnaire), and health-related quality of life. Univariate analyses were used to determine the association between individual characteristics and work-related outcomes. Of the 89 patients who had worked before the index myocardial infarction, 21 (23.6%) did not return to work. Variables associated with the outcome of not returning to work were past myocardial infarction (before the index myocardial infarction), coronary artery bypass graft surgery, heart failure, positive stress test, and low score on the Physical Component Summary (PCS-12) scale of the Short Form-12. Patients who did not return to work also tended to have more comorbidities and take more prescribed drugs than those who returned to work. Median WPS scores were higher for patients who had higher ejection fractions at discharge, had not experienced a myocardial infarction before the index event, underwent a percutaneous revascularization intervention at the time of hospitalization, and had not recently been absent from work. Workers reporting absences had lower PCS-12 scores than their counterparts or reported a rehospitalization before the survey. CONCLUSION: Preexisting cardiac disease and poorer physical functioning were consistently related to worse work-related outcomes. This small study demonstrates the need for a larger, broader study that includes health beliefs, treatment, and other job and patient factors that may influence work-related outcomes.

Absenteeism↗
PubMed1976

Analysis of the microfilarial periodicity of Dirofilaria immitis.

Microfilarial periodicity displayed by dogs infected with Dirofilaria immitis was analyzed using the methematical model proposed by Sasa and Tanaka (S.E. Asian J. Trop. Med. and Pub. Health 4, 1974, 518-536) except that Pearson's product-moment correlation test was substituted for their Chi-square analysis to estimate goodness of fit. Samples were drawn at 3 hour intervals for periods of 24 or 48 hours in a series of 10 studies conducted on 4 dogs. No significant differences were observed in microfilarial concentration between samples of venous and cutaneous capillary blood. Significant correlation of observed microfilarial densities with the values predicted by the model were observed in 7 of the 10 studies with r2 values ranging from 78.8 to 95.3%. The periodicity index ranged from 28.33 to 53.50 in these 7 studies and thus fell in the subperiodic category. The estimated hour of peak microfilarial density was not confined to the late afternoon as generally believed; for example, values of 04:00 and 22:00 hours were observed. Thus D. immitis microfilaremia cannot accurately be characterized either as diurnal or as nocturnal. Observation of the behavior of the experimental dogs led to an hypothesis that emotional and environmental stresses placed on the host may induce transients in the microfilarial density that may overwhelm or obscure the periodicity function.

Animals↗
PubMed1981

Noninvasive evaluation of the hemodynamic effects of closure of atrial septal defects of the secundum type.

In order to examine the feasibility of using multiple noninvasive methods in monitoring the hemodynamic changes induced by operation for atrial septal defect of the secundum type, 12 consecutive patients were examined before operation and 8 days afterwards. 10 of the patients were re-examined after one year. The methods used were echocardiography calibrated apexcardiography and systolic time intervals. It was possible with echocardiography to demonstrate a decrease in right ventricular end diastolic diameter and left atrial dimension already at the first postoperative study, but these changes were more marked after one year, though the right ventricular end diastolic diameter continued to be larger than normal. The left ventricular end diastolic diameter initially increased in size probably due to increased filing, but later returned somewhat towards the preoperative value. Functionally the apexcardiogram revealed an early decrease in left ventricular compliance probably due to the increased filling, but normal compliance after one year, where also the initially prolonged early relaxation time returned towards the normal value. The other apexcardiographical measurements did not change. Systolic time intervals showed an improved cardiac performance, as evaluated by preejection period index and preejection period/left ventricular ejection time, most marked at the early postoperative measurement. This is considered to be due to the improved left ventricular filling (The Starling effect) and not to changes in the myocardium itself.

Adolescent↗
PubMed2003

Effect of S6 tail mutations on charge movement in Shaker potassium channels.

The cytoplasmic ends of the four S6 transmembrane segments of voltage-gated potassium channels converge in a bundle crossing that acts as the activation gate that opens in response to a depolarization. To explore whether the cytoplasmic extension of the S6 segment (the S6 tail) plays a role in coupling voltage sensor and activation gate movements, we examined the effect of cysteine substitution from residues N482 to T489 on the kinetics and voltage-dependence of S4 charge movement and on the kinetics of deactivation of ionic current. Among these mutants, F484C has the steepest voltage-dependent charge movement, the largest Q-V shift, and the fastest OFF gating currents. Further study of the residue at position 484, using mutagenesis and modification of F484C by cysteine reagents, suggests that aromaticity at this position is essential to maintain normal coupling. We used periodicity analysis to appraise the possibility that the S6 tail has an alpha-helical structure. Although we obtained an alpha-periodicity index of 2.41 for gating current parameters, a new randomization test produced an indecisive conclusion about the secondary structure of this region. Taken together, our results suggest that the tail end of S6 plays an important role in coupling between activation gating and charge movement.

Cell Membrane Permeability↗
PubMed1975

Assessment of left ventricular function in secundum atrial septal defect: evaluation by determination of volume, pressure, and external systolic time indices.

Left ventricular function and volume data from 17 control subjects and 27 young patients with secundum atrial septal defect (ASD) without overt left or right ventricular failure were compared. ASD patients were subdivided in low shunt (Qp/Qs less than 2.0) and high shunt (Qp/Qs larger than or equal to 2.0) groups. Mean left ventricular (LV) stroke volume was significantly less in ASD patients (46 +/- 16 ml/m2 in the low shunt and 44 +/- 9 ml/m2 in high shunt group) compared with control patients (51 +/- 13 ml/m2, P less than 0.01 and P less than 0.02, respectively). There was no significant difference in mean left ventricular end-diastolic volume (LVEDV) between any group of patients (control subjects 67 +/- 17 ml/m2; low shunt ASD 66 +/- 17 Ml/m2, and high shunt ASD 62 +/- 12 ml/m2). High shunt ASD had a significantly lower cardiac index compared with control patients (5.0 liters/min/m2 vs. 5.9 liters/min/m2, P less than 0.02). Both low shunt and high shunt ASD showed significantly lower stroke work indices than control subjects (42 +/- 13 GmM/m2 and 37 +/- 8 GmM/m2 compared with 51 +/- 14 GmM/M2 , P less than 0.05 and P less than 0.001, respectively) but only the high shunt group had a significantly lower peak systolic pressure (94 +/- 12 mm Hg vs. 109 +/- 11 mm Hg for control patients, P less than 0.01). There was no significant difference between the control and ASD groups in LV end-diastolic, mean right atrial, right ventricular end-diastolic, and pulmonary pressures. External systolic time intervals were compared in 5 control and 12 ASD patients. There was no significant difference between the two groups of patients in absolute values or indices for pre-ejection period, ejection time, or electromechanical systole. However, the ratio of the pre-ejection period index to left ventricular ejection time index (PEPI/LVETI) was significantly higher in ASD patients (P less than 0.05). In young subjects with large shunt ASD, certain indicators of left ventricular function are depressed. Evaluation of PEPI/LVETI may allow noninvasive determination of LV function.

Adolescent↗
PubMed1986

Popular press coverage of eight National Institutes of Health consensus development topics.

The quality of medical journalism has been widely criticized. As part of a larger evaluation study, we analyzed popular press coverage of eight topics selected by the National Institutes of Health for consensus development conferences in 1979 and 1980. Using periodical indexes to identify relevant articles, we analyzed the characteristics of 269 topical articles published in newspapers and magazines in the four years surrounding each conference and examined the role that the conference played in subsequent reporting. Most topics received widespread press interest that culminated around the time of each conference. Consensus findings were widely cited in articles that appeared after the conferences. Articles were mostly factual and balanced, relied on experts, and emphasized major themes covered by the conference. We conclude that the popular press can make an important contribution to the dissemination of new medical information.

National Institutes of Health (U.S.)↗
PubMed2004

Mixed versus manic bipolar disorder: a comparison of demographic, symptomatic, and treatment differences.

This study compared patients diagnosed with Mixed versus Manic Bipolar disorder across the domains of demographic, symptom, and treatment variables. The sample included 152 patients who were admitted to an acute care psychiatric facility within an index period, whose discharge diagnosis was either Bipolar Disorder, Manic Episode (n = 109) or Bipolar Disorder, Mixed Episode (n = 43). No significant differences were found in age, race, episode number, or length of stay. There was a trend toward females being diagnosed with a Mixed Episode and males a Manic Episode. Group differences were found on physician and nurse symptom ratings, with the manic group receiving higher ratings on resistance, psychosis, and conceptual disorganization and the mixed receiving higher scores on depression and anxiety. On self-report measures, the mixed group endorsed greater severity than did the manic group. The mixed group was more likely to be prescribed antidepressants at discharge; however there were no significant differences across other medication. These differences are discussed.

Adult↗
PubMed1997

Identification of psychiatric distress by primary care physicians.

The aims of the present study were to evaluate the extent to which primary care physicians' (PCPs) identification of psychiatric distress is related to a number of nonpsychopathological factors, such as patient sociodemographic and health-related characteristics, and to assess the impact of depression on PCP identification of psychiatric distress, controlling for patient sociodemographic and health-related characteristics. Two patient samples were chosen to explore these issues: 1) patients not fulfilling any ICD-10-defined or subthreshold psychiatric diagnosis and, 2) patients with an ICD-10 diagnosis of current depression. Patients attending 46 primary care clinics during an index period were screened by the General Health Questionnaire (GHQ)-12 and selected for a second stage interview according to GHQ score. Among the 559 interviewed patients, 123 had no mental disorder and 66 had an ICD-10 current depressive disorder. Identification of psychiatric distress by the PCP was associated with retirement among subjects without mental disorders but not among depressed patients. Patient's negative overall health self-perception and severity of physical illness were significantly related to identification of psychiatric distress in the two groups, whereas neither disability nor reason for medical consultation had a significant effect. Patients with current depression, compared with those without, were 4.3 times more likely to be identified by PCPs as having psychiatric distress when adjusting for all the above nonpsychopathological variables. Patients with depression and comorbid anxiety disorders were more likely to be recognized by the PCP as compared with those with pure depression. Finally, among depressive symptoms, diurnal variation and symptoms related to suicidal tendencies were predictive of identification of psychiatric distress, whereas increase of appetite was negatively associated with PCP recognition.

Adult↗
PubMed2004

Second-trimester genetic amniocentesis: 5-year experience.

AIMS: The purpose of this study is to evaluate the data related to the genetic amniocentesis performed in a single university hospital. METHODS: Medical records were used to analyze indications of amniocentesis, the results of chromosome analysis, complications and pregnancy outcomes from January 1998 through January 2002. Anomaly screening was performed to all patients attending to our Obstetrics and Gynecology Department between 16 and 20 weeks of pregnancy. The staff obstetricians-gynecologists performed all of the second-trimester genetic amniocentesis. RESULTS: Totally 2,686 patients attended to our department between 16 and 20 weeks of pregnancy during the index period. A total of 131 genetic amniocentesis were performed. The indications were advanced maternal age (cut off age 35) in 24, suspicion of genetic abnormality on ultrasound in 15, history of siblings with Down syndrome in 2 and abnormal triple screen in 90 patients, respectively. There were two pregnancy losses due to the procedure; thus the overall complication rate of second-trimester genetic amniocentesis was 1.5%. CONCLUSIONS: Being one of the most performed invasive techniques for prenatal diagnose, second-trimester genetic amniocentesis is a reliable and safe method. Although the size of this study is limited, our complication rates are similar to the related literature.

Adolescent↗
PubMed1990

Noninvasive assessment of cardiac performance of intravenous benzodiazepines by systolic time intervals.

The effects of anesthetic induction by diazepam, flunitrazepam and midazolam on cardiac performance were evaluated in 33 ASA class I surgical patients (average age was 36 years). The patients were divided according to the 3 drug groups, and the effects of each drug assessed utilizing measurements of systolic time intervals. An increase in heart rate and decrease in blood pressure was observed following flunitrazepam and midazolam induction. There was no changes in PEPI (pre-ejection period index) and LVETI (left ventricular ejection time index) by benzodiazepines induction. The PEP/LVET ratio was increased by diazepam while the DPTI (diastolic pressure time index)/TTI (tension time index) was reduced by flunitrazepam and midazolam. However, these changes in PEP/LVET and DPTI/TTI were within normal limits. These data indicate that in healthy humans the induction dose of either diazepam, flunitrazepam or midazolam does not extremely influence either PEP/LVET for cardiac performance or DPTI/TTI for cardiac oxygen balance. The results also suggest that the simultaneous use of PEP/LVET and DPTI/TTI is more informative than any single variable for the evaluation of cardiac effects of anesthetics.

Journal Article↗
PubMed2005

Efficacy of salmon calcitonin in complex regional pain syndrome (type 1) in addition to physical therapy.

The aim of the study was to assess the efficacy of salmon calcitonin, which was suggested as effective in the treatment of complex regional pain syndrome type 1 (CRPS 1). Patients who had suffered trauma to their upper extremities and developed CRPS 1 were included into this randomised, controlled single-blind study. The diagnosis was made according to the clinical examination and scintigraphy. The evaluation parameters were: pain [visual analogue scale (VAS)], the angle of dorsiflexion (DF) and palmar flexion (PF) of the wrist, distance between the fingertip and distal palmar crease (FT-DPC), allodynia, hyperalgesia and trophic changes. One group received paracetamol 1500 m/day and the other group salmon calcitonin 200 IU/day for 2 months. All of the patients participated in a physical therapy and exercise programme. A total of 35 patients were divided into two groups, who were found to be similar for age, body mass index, period of trauma, period of rest in a plaster splint or bandage, the duration of symptoms, VAS, DF and PF angle, FT-DPC, presence of allodynia, hyperalgesia and trophic changes (p>0.05). The control examination showed similar results for allodynia, hyperalgesia and trophic changes, whereas remarkable improvement was observed in the rest of the parameters within groups. On the other hand, between the two groups there was no significant difference in any of the parameters (p>0.05) This randomised, single-blind study showed that all of the patients with acute CRPS 1 in their upper extremities after trauma, who were treated with either paracetamol or calcitonin along with physical therapy, recovered in all parameters significantly, but without any difference between groups. We can conclude that calcitonin does not make any favourable contribution in the treatment of patients with acute CRPS 1; physical therapy combined with only a simple analgesic is an efficient means of therapy.

Acetaminophen↗
PubMed1979

Noninvasive assessment of myocardial function in young patients with mitral valve prolapse.

To evaluate myocardial function in patients with documented mitral valve prolapse (MVP) 14 patients (six men and eight women with a mean age of 28 +/- 6.3 years) were examined noninvasively. Systolic time intervals were recorded at rest (in the supine and upright position) and after bicycle ergometry (upright position) and were compared with 10 healthy control subjects of similar age. Tracings were coded with random numbers and were evaluated by two blinded investigators. Contractility indices such as pre-ejection period index (PEPc) and ratio pre-ejection period/left ventricular ejection time (PEP/LVET) revealed no significant differences between patients and controls both at rest and after exercise. We conclude that young patients with MVP have no evidence for impaired myocardial function, provided there is no significant mitral incompetence or associated heart disease.

Adult↗
PubMed1982

Left ventricular systolic and diastolic function in hyperthyroidism.

In order to assess the effect of hyperthyroidism on systolic and diastolic function of the left ventricle, M-mode echocardiograms and systolic time intervals were obtained in 13 patients while they were clinically hyperthyroid and again when they were euthyroid following radioactive iodine therapy. Echocardiographic tracings of the septum and left ventricular posterior wall were digitized and analyzed to provide the maximum velocity of shortening and maximum velocity of lengthening. These velocities were normalized for left ventricular diastolic dimension. The left ventricular minor axis fractional shortening and the normalized maximum velocity of shortening were both increased during the hyperthyroid state. The normalized maximum velocity of lengthening, a measure of diastolic left ventricular function, was also increased during the hyperthyroid state when compared to the euthyroid state. The preejection period index and the preejection period/left ventricular ejection time ratio were lower when the patients were hyperthyroid than when they were euthyroid. These data confirm the increased inotropic state and demonstrated increased diastolic relaxation velocities of the hyperthyroid left ventricle.

Adult↗