Emission- and fluorescence-spectroscopic investigation of a glow discharge plasma: absolute number density of radiative and nonradiative atoms in the negative glow

The excited-state atom densities in the negative glow of a direct-current glow discharge are derived from the spectral-line intensity of radiative atoms and the resonance-fluorescence photon flux of nonradiative atoms. The discharge is operated in a helium-argon gas mixture (molar fraction ratio 91:9; total gas pressure 5 Torr) at a dc current of 0.7-1.2 mA. The observations are made in the region of the maximum luminance in the cathode region, where high-energy electrons accelerated in the cathode fall are injected into the negative glow. The emission intensities of the He I, He II, Ar I, and Ar II spectral lines are measured with a calibrated tungsten ribbon lamp as an absolute spectral-radiance standard. Fluorescence photons scattered by helium and argon atoms in the metastable state and argon atoms in the resonance state are detected by the laser-induced fluorescence (LIF) method with the Rayleigh scattering of nitrogen molecules as an absolute standard of scattering cross section. The laser absorption method is incorporated to confirm the result of the LIF measurement. Excitation energies of the measured spectral lines range from 11.6 (Ar I) to 75.6 eV (He II), where the excitation energy is measured from the ground state of the neutral atom on the assumption that, in the plasma of this study, both the neutral and the ionic lines are excited by electron impact in a single-step process from the ground state of the corresponding neutral atoms. Experimental evidence is shown for the validity of this assumption.

[Viral infection related to the appearance of acute bacterial respiratory tract infections]

To investigate what viruses are related to acute bacterial respiratory tract infections, we prospectively evaluated 113 cases with respiratory tract infections (always accompanying by purulent sputum) experienced between July 1998 and March 2000. Acute viral infections were detected in 25 cases (22%); 10 cases of influenza A virus and 6 cases of respiratory syncytial (RS) virus. The epidemiology of the influenza A virus and RS virus was mainly identified as from December to February in both winter seasons. A bacteriological examination of sputum cultures isolated 12 cases of Streptococcus pneumoniae and 10 cases of Haemophilus influenzae during the same periods and mixed infections of both viruses and bacteria were recognised in 16 cases (14%). These results suggest a significantly high percentage of mixed infections of both viruses and bacteria. However, it was unknown whether the patients with acute bacterial respiratory infections had been infected with viruses prior to the bacterial infections. The frequency of appearance of respiratory tract infections tended to increase with the seasonale epidemiology of viral infections.

[A case with infectious mononucleosis-like syndrome caused by human herpes virus-6 infection]

A 26-year-old female was admitted because of multiple fractures in lower extremities. While in the hospital, she developed a high fever and generalized skin eruption. Physical examination revealed bilateral cervical lymphadenopathy and mild hepatosplenomegaly. The white cell count was 11,200 with 11% atypical lymphocytes. Serum GOT, GPT, LDH were markedly elevated. Infectious mononucleosis was suspected, but the serological test for EB virus did not show evidence of acute EB virus infection. Anti-HSV, CMV, hepatitis A virus antibody titers also did not show significant change during the coarse. The serological test for HHV-6 only showed increased titer of IgM and IgG antibodies. Rapidly elevated IgG antibody titer was indicative of reactivation of HHV-6. So, she was diagnosed as mononucleosis-like syndrome caused by HHV-6, probably reactivated infection. Her symptoms gradually disappeared during a month.

[Evaluation of intramyocardial coronary flow velocity pattern before and after surgical repair of Bland-White-Garland syndrome by pulsed Doppler echocardiography]

Anomalous origin of the left main coronary artery from the pulmonary artery (Bland-White-Garland syndrome) is a rare congenital anomaly. Intramyocardial coronary flow dynamics by pulsed Doppler echocardiography were studied in three patients with this syndrome who underwent surgical repair by Hamilton's method. Before surgery, the intramyocardial flow at the ventricular septum showed a retrograde velocity pattern which had two peaks in systole and diastole in all patients. After surgery, two patients with successful repair showed a biphasic intramyocardial flow pattern which consisted of retrograde and antegrade flows in systole and diastole, respectively. In contrast, one patient who had a residual shunt between the left coronary artery and the pulmonary artery showed a biphasic pattern which had antegrade flow in systole and retrograde flow in diastole. These results may suggest that the evaluation of postoperative intramyocardial coronary flow velocity pattern by pulsed Doppler echocardiography is useful for detecting a residual shunt after surgical repair of Bland-White-Garland syndrome.

[Diagnosis of coronary artery dehiscence and pseudoaneurysm after modified Bentall operation by Doppler color flow imaging: a case report]

This 48-year-old man presented with anterior chest and back pain in 1981. He was treated with replacement of the ascending aorta and aortic valve under a diagnosis of dissection of the ascending aorta with severe aortic regurgitation. He underwent modified Bentall reoperation for the dilation of the aortic root in 1991. Postoperative two-dimensional echocardiography was performed because of sustained atrial flutter. An echo-free space was detected between the aorta graft and aorta wrapping on the short-axis view. Doppler color flow imaging revealed blood flow from the left coronary artery graft into the echo-free space. This leakage was suspected to be the cause of the echo-free space. Transesophageal echocardiography was performed to conform this hypothesis, which revealed blood flow from the left coronary artery graft into the echo-free space in systole and flow into the left coronary artery graft from the echo-free space in diastole.

[Timing of inflow to the atrium after ventricular contraction and relaxation: effect of atrial wall stiffness]

A stiff atrium is sensitive to even a small change in its volume, causing a rapid change in the caval vein flow. We hypothesized that the onset of caval vein flow may follow immediately after the onset of a ventricular event in a patient with a stiff atrium. The timing of inflow into the right ventricle and into the atrium were examined by Doppler echocardiography in 20 healthy subjects, 12 patients with constrictive pericarditis, and 10 patients with cardiac tamponade. The onset of diastolic flow in the superior vena cave followed 17 +/- 14 msec after the onset of early diastolic filling flow into the right ventricle in constrictive pericarditis patients, which was significantly shorter than 107 +/- 45 msec in the healthy subjects. The onset of systolic flow occurred 178 +/- 46 msec after the peak of the R wave of the electrocardiogram in cardiac tamponade patients, which was significantly longer than 129 +/- 17 msec in healthy subjects. This time was slightly shorter in constrictive pericarditis (103 +/- 21 msec). We conclude that a short time lag from the onset of a ventricular event to the onset of caval flow indications that the right atrium is stiff.