Effect of exercise on left ventricular mechanical efficiency in conscious dogs

BACKGROUND

We studied the effect of exercise (7.2 to 8.0 km/h) on the efficiency of the conversion of metabolic energy to external work or stroke work (SW) by the left ventricle (LV).

METHODS AND RESULTS

Energy use was calculated from LV myocardial oxygen consumption per beat (MVO2). LV volume was calculated from orthogonal dimensions and coronary flow measured with ultrasonic flow probes. The total mechanical energy of the LV was calculated as the pressure-volume area (PVA). At rest, the MVO2-PVA point fell on the MVO2-PVA relation determined by steady-state changes in arterial pressure produced by graded infusions of phenylephrine. Exercise increased the slope (Ees) of LV end-systolic pressure-volume (PV) relation by 29%. During exercise, the MVO2-PVA point shifted to the right only slightly above the control MVO2-PVA relation by 0.007 +/- 0.005 mL O2.beat-1.100 g LV-1. Despite the increase in ventricular contractility with exercise, the PVA/MVO2 ratio was unchanged because of the marked increase in PVA. During exercise, the transmission of total mechanical energy to external work (SW/PVA) increased from 65 +/- 5% to 72 +/- 4% (P < .01) as the ratio of the arterial end-systolic elastance to Ees decreased from 1.1 +/- 0.2 to 0.8 +/- 0.1 (P < .05). Thus, LV mechanical efficiency (SW/MVO2 = SW/PVA.PVA/MVO2) improved from 12.9 +/- 1.5% to 14.3 +/- 1.1% (P < .05) during exercise.

CONCLUSIONS

Exercise increases the efficiency of conversion of metabolic energy to external work by the LV due to alteration in LV arterial coupling resulting in increased production of mechanical energy and enhanced transmission of mechanical energy to external work, which more than offsets any increased metabolic cost of the enhanced contractility.

Preliminary X-ray crystallographic studies of photosynthetic reaction center from a thermophilic sulfur bacterium, Chromatium tepidum

A membrane protein complex, photosynthetic reaction center purified from the thermophilic purple sulfur bacterium, Chromatium tepidum has been crystallized from a phosphate buffer containing a detergent, n-octyl-beta-D-glucopyranoside and a precipitant, polyethylene glycol 4000. The crystals diffracted X-rays beyond 3A resolution with synchrotron radiation and are suitable for high-resolution X-ray crystallographic studies. The crystals belong to the orthorhombic space group P2(1)2(1)2(1) with unit-cell dimensions of a = 136A, b = 197A, and c = 82A. Assuming that they contain one reaction center complex in the asymmetric unit, VM was calculated to be 4.3 A3/Da, which agrees with the values obtained in the membrane protein complexes.

Structures of chlorosomes and aggregated BChlc inChlorobium tepidum from solid state high resolution CP/MAS(13)C NMR

Cross polarization/magic angle spinning (CP/MAS)(13)C (solid state high resolution) NMR spectra were observed for chlorosomes and BChlc aggregates. Similarity of both kinds of spectra (except for some signals assignable to proteins and lipids in chlorosomes) indicates that BChlc's in chlorosomes are present just as in synthetic BChlc aggregates. Chemical shifts for C13(1) carbonyl and C3(1) hydroxylethyl carbons indicate hydrogen bonding between them. Comparison of solution and solid state(13)C NMR chemical shifts shows the five coordinated nature of BChlc aggregates. Some chemical shift differences were attributable to ring currents shifts. Their comparisons with calculated ring current shift values predicted structures for the aggregates. Cross polarization dynamics of the CP/MAS(13)C NMR signals explored dynamic and structural nature of the BChlc aggregates.

Ejecting activation differs in energetics from ordinary positive inotropism in the canine left ventricle

Ventricular ejection is known to have dual effects on the end-systolic pressure: the ejecting deactivation by a relatively large ejection against a low afterload versus the ejecting activation by a relatively small ejection against a high afterload. We studied how the increase in contractility index (Emax) by the ejecting activation would affect myocardial oxygen consumption (VO2). To this end, left ventricular steady-state ejecting contractions were produced with various stroke volumes from a fixed end-diastolic volume in an excised cross-circulated canine heart. The effect of the ejection-activated Emax on VO2 was assessed by the relation between VO2 and pressure-volume area (PVA). PVA is the total mechanical energy generated by ventricular contraction. In contrast to the elevation of the linear VO2-PVA relation in a parallel manner with an enhanced Emax by ordinary positive inotropic agents such as catecholamines and calcium, the ejection-activated Emax did not elevate the VO2-PVA relation. This result indicates that the ejecting activation enhances Emax in an energetically different manner from ordinary positive inotropism in the canine left ventricle.

Presence and significance of minor antenna components in the energy transfer sequence of the green photosynthetic bacterium Chloroflexus aurantiacus

Antenna components in the energy transfer processes of a green photosynthetic bacterium Chloroflexus aurantiacus were spectrally investigated by time-resolved fluorescence spectroscopy at -196 degrees C on intact cells. Besides major antenna components so far reported, three minor components were resolved; those were Bchl c located at 785 nm, the baseplate Bchl a at 819 nm and Bchl a in the B808-866 complex at 910 nm. The last component was assigned to a longer wavelength antenna closely associated with a reaction center. An additional Bchl c fluorescence component was kinetically suggested to be present, which can be an energy donor to a major Bchl c. Presence of these minor components was signified in terms of (1) increase in the spectral overlap integral and (2) adjustment of the direction of dipole moments in the energy transfer sequence of intact cells.

Relation between left ventricular oxygen consumption and pressure-volume area in conscious dogs

BACKGROUND

The relation between left ventricular (LV) oxygen consumption (MVO2) and pressure-volume area (PVA) developed in isolated hearts provides a powerful method to understand cardiac energetics. We investigated application of this relation to the intact circulation, determining its response to steady-state and transient load alterations and enhanced contractility in conscious animals.

METHODS AND RESULTS

Eight dogs were instrumented to measure LV pressure (micromanometer), LV volume (three sonomicrometers), and left circumflex and anterior descending coronary artery flows (ultrasonic flowmeter). Data were acquired after recovery from the surgery with the animals awake and unsedated. After administration of hexamethonium and atropine, steady-state loading conditions were changed with phenylephrine or nitroprusside in four to five steps before and during the infusion of dobutamine (6 to 10 micrograms.-1kg.-1min). MVO2 and PVA obtained under steady-state conditions were linearly correlated both before and during dobutamine. The MVO2-PVA relation obtained on a beat-to-beat basis during transient caval occlusion was less linear and not coincident with the steady-state relation. Dobutamine shifted the steady-state MVO2-PVA relation upward in all hearts, increasing the MVO2 axis intercept of the MVO2-PVA relation (P < .01). This intercept correlated with ventricular contractility assessed by the slope (Ees) of the LV end-systolic pressure-volume relation determined by caval occlusion (r = .76, P < .05). The slope of the MVO2-PVA relation increased with dobutamine in seven of eight animals, with the inverse of the slope (representing contractile efficiency) being 31 +/- 6% during control and 24 +/- 6% after dobutamine (P = .06).

CONCLUSIONS

MVO2 and PVA are linearly related during steady-state alterations in loading conditions in conscious dogs but not on a beat-by-beat basis during transient caval occlusion. Increase in contractility by dobutamine produces an upward shift of the MVO2-PVA relation.

[EEG and polysomnography findings in patients with dyskinesia]

It is known that EEG findings reveal various abnormalities in patients with involuntary movement. But these findings are not specific. It has been reported to be related to myoclonus and spike. The other involuntary movement is unknown to the relation to EEG findings. The involuntary movement usually disappears during sleep, but a certain involuntary movement appears only during sleep. In the patient with Huntington's chorea and dystonia musculorum deformans, PSG reveals an increase in interspersed wakefulness, decrease of deep sleep and prolongation of REM latency. Periodic limb movement and nocturnal paroxysmal dystonia appear only during sleep. Nocturnal sleep studies are important for exploring the pathophysiology in involuntary movement.

Importance of non-stenosed donor coronary arteries for collateral flow reserve

To elucidate whether the presence of significant stenoses in donor coronary arteries compromises collateral flow reserve, coronary arteriography was performed in 22 patients with stable effort angina who had a complete obstruction in one of the major coronary arteries. The patients were divided into two groups according to the absence (group I: n = 11) or presence (group II: n = 11) of significant stenoses (> or = 75% stenosis of the luminal diameter) in donor arteries. After conventional cardiac catheterization, coronary arteriography was repeated before and during rapid atrial pacing. Coronary collateral circulation was evaluated by means of angiographic contrast appearance time (CAT) which was defined as the time (s) until the epicardial segments distal to the site of complete occlusion were opacified after the injection of contrast medium into the donor artery. The pressure gradient across the collateral circulation (mean aortic pressure minus left ventricular end-diastolic pressure) remained unchanged before and during rapid atrial pacing (group I: 95 +/- 14 vs. 99 +/- 15 mmHg; group II: 91 +/- 18 vs. 94 +/- 16 mmHg). Rapid atrial pacing decreased the contrast appearance time in group I from 1.73 +/- 0.34 to 1.47 +/- 0.37 s (P < 0.01), but was not changed in group II from 1.68 +/- 0.36 to 1.73 +/- 0.51 s (P = n.s.). It was concluded that coronary collateral circulation is further augmented in response to an increase in myocardial oxygen demand in patients with non-stenosed donor coronary arteries and significant stenoses in donor arteries compromise an increase in collateral blood flow.

Effect of heart failure on the mechanism of exercise-induced augmentation of mitral valve flow

The exercise response of left ventricular (LV) filling dynamics may be altered by congestive heart failure (CHF). Accordingly, we studied 18 conscious dogs, instrumented to measure micromanometer LV and left atrial (LA) pressures and determine LV volume from three dimensions. CHF was produced by 4-5 weeks of right ventricular rapid pacing. Before CHF, exercise (5.5-8.5 mph for 8-15 minutes) increased the maximum rate of LV filling (dV/dtmax) (197 +/- 37 versus 297 +/- 56 ml/sec [mean +/- SD], p < 0.05) in response to an increase in the maximum early diastolic LA to LV pressure gradient (5.8 +/- 2.0 versus 9.8 +/- 1.9 mm Hg, p < 0.05) produced by a fall in minimum LV pressure (1.0 +/- 2.9 versus -3.9 +/- 3.1 mm Hg, p < 0.01), whereas mean LA pressure was unchanged (6.4 +/- 3.1 versus 6.4 +/- 4.2 mm Hg, p = NS). The time constant of LV relaxation was shortened (28.1 +/- 3.2 versus 21.0 +/- 4.2 msec, p < 0.05). After CHF, dV/dtmax (141 +/- 51 versus 200 +/- 59 ml/sec, p < 0.05) and the maximum LA to LV pressure gradient (6.0 +/- 1.1 versus 11.1 +/- 2.7 mm Hg, p < 0.05) continued to increase with exercise (3-5.0 mph for 4-8 minutes). However, the time constant of LV relaxation was prolonged (35.6 +/- 4.8 versus 38.9 +/- 5.5 msec, p < 0.05), and minimum LV pressure (15.1 +/- 5.6 versus 17.6 +/- 5.9 mm Hg, p < 0.05) and mean LA pressure increased (22.6 +/- 7.2 versus 29.1 +/- 7.3 mm Hg, p < 0.05). These altered effects of exercise on LV diastolic filling dynamics persisted when heart rate and wall stress during exercise before and after CHF were matched by varying the level of exercise. We conclude that, during normal exercise, mitral valve flow is augmented by a fall of early diastolic LV pressure without a rise in LA pressure. After CHF, early diastolic LV pressure does not fall but increases during exercise. Thus, the increase in the early diastolic LA to LV pressure gradient and the rate of mitral valve flow results from an increase in LA pressure during exercise after CHF. This study suggests that the failure of the enhancement of LV relaxation and an increase in early diastolic LV pressure with exercise after CHF may contribute to exercise intolerance in CHF.

Oxygen consumption for constant work is minimal at lowest working contractility in normal dog hearts

We tested whether minimal myocardial oxygen consumption (MVO2) for a given external work would exist in the middle of a normal contractility range as previously predicted theoretically. The left ventricle of the excised cross-circulated dog heart preparation was connected to a volume servo pump. Myocardial contractility in terms of ventricular end-systolic elastance (Emax) was gradually increased from control 8.9 +/- 3.4 (mean +/- SD) to 30.0 mmHg/(ml/100 g) by epinephrine and decreased to 1.8 mmHg/(ml/100 g) by propranolol while heart rate, end-systolic pressure and stroke work were kept constant. MVO2 was determined as the product of total coronary flow and coronary arteriovenous oxygen content difference in each contractile state. We plotted MVO2 values against E(max) values in each heart. The MVO2-E(max) relation for a constant cardiac work showed that MVO2 was minimal at the low end of the covered E(max) range. We conclude that minimal MVO2 for a given cardiac work is generally obtained at the lowest working contractility in normal dog hearts. This conclusion might pose some problems in the previous theoretical prediction as to the contractility that achieves the minimal MVO2 in a given external work.

Comparative efficacy of thrombolytic therapy for acute myocardial infarction in patients with and without chronic preinfarction angina

To resolve the question of whether coronary thrombolysis for acute myocardial infarction is more effective in patients with or in those without chronic preinfarction angina, we retrospectively analyzed cineventriculograms in 54 patients with the first anterior Q-wave myocardial infarction during the chronic stage of myocardial infarction. Patients were divided into 2 groups according to the presence (group A, n = 24) or absence (group B, n = 30) of chronic preinfarction angina. In group A, 16 had either intracoronary (n = 6) or intravenous (n = 10) coronary thrombolysis with urokinase within 6 h after the onset of acute myocardial infarction. In group B, 11 had either intracoronary (n = 4) or intravenous (n = 7) coronary thrombolysis within 6 h after the onset of acute myocardial infarction. Global left ventricular ejection fraction and regional wall motion in infarct areas were evaluated quantitatively. In group A, the percentage of systolic segment shortening in infarct areas was 20 +/- (SD) 16% in patients with thrombolytic therapy and 17 +/- 15% in those with conventional therapy (p = NS). By contrast, in group B, the regional wall motion in infarct areas was significantly (p < 0.01) better in patients with thrombolytic therapy compared to those with conventional therapy (13 +/- 10 vs. 3 +/- 8%). Thus, patients without chronic preinfarction angina might benefit from coronary thrombolysis, while in those with preinfarction angina the beneficial effect of thrombolytic therapy may be relatively limited.

Dobutamine improves afterload-induced deterioration of mechanical efficiency toward maximal

We studied the effect of increased afterload on the ratios of O2 consumption (VO2) to external work (EW), VO2 to the systolic pressure-volume area (PVA), and PVA to EW at control state and with dobutamine in the left ventricles of open-chest dogs. Left ventricular volume was measured with a volumetric conductance catheter and coronary flow with an electromagnetic flowmeter. Hexamethonium bromide and atropine sulfate were administered before changes in end-systolic pressure (Pes) with an infusion of nitroprusside or angiotensin II. Dobutamine enhanced ventricular end-systolic elastance by 100%. In the control, with increases in Pes, EW/VO2 remained unchanged, PVA/VO2 increased by 48%, and EW/PVA decreased by 26%. Dobutamine increased both EW/VO2 and EW/PVA at any given Pes but decreased PVA/VO2. During dobutamine, EW/VO2 increased significantly with increases in Pes. The ratio of measured EW/VO2 to the theoretically predicted maximal EW/VO2 value for a given end-diastolic volume and contractility was 0.83 at a Pes of 70 mmHg, and this ratio decreased by 33% with increases in Pes in the control. During dobutamine, measured EW/VO2 values were almost equal to each corresponding theoretical maximal value, and the average decrease in the ratio with increases in Pes was 7%. Thus the enhanced inotropic state by dobutamine can restore the afterload-induced deterioration of EW/VO2 toward the normal maximal level.

The inverted hexagonal phase is more sensitive to hydroperoxidation than the multilamellar phase in phosphatidylcholine and phosphatidylethanolamine aqueous dispersions

The effect of phase behaviour (hexagonal II phase and lamellar phase) on the peroxidation of membrane phospholipids has been investigated in dilinoleoyl phosphatidylcholine (DLPC)/dilinoleoyl phosphatidylethanolamine (DLPE) aqueous dispersions. Peroxidation was initiated with a water-soluble radical inducer 2,2'-azobis (2-amidino-propane) dihydrochloride (AAPN). The phospholipid morphology was monitored by 31P-nuclear magnetic resonance (NMR). Phospholipid hydroperoxides (PCOOH and PEOOH) were determined by chemiluminescence high-performance liquid chromatography (CL-HPLC). In pH-induced phase transition systems, DLPE in the bilayer state was much less oxidized than in the hexagonal II state. In composition-induced phase transition systems, the formation of total hydroperoxides and the consumption of alpha-tocopherol in the hexagonal II phase were greater than in the bilayer phase. These data suggest that the hexagonal II phase is more sensitive to hydroperoxidation than the bilayer phase in phospholipid aqueous dispersions.

Serial reproducibility of conductance catheter volumetry of left ventricle in conscious dogs

Although the conductance catheter technique has been currently applied to in situ measurement of left ventricular volume, reproducibility of this method has not been examined within the same subject on separate days. Accordingly, serial catheter volumetries (mean 5 days apart) were performed in 10 normal conscious dogs, which were chronically instrumented with the conductance catheter, a micromanometer, and caval cuff occluders. Left ventricular end-systolic pressure-volume relationship was also determined during transient caval occlusion. All hemodynamic variables were compared at the same heart rate. There were no significant changes in blood resistivity (10 +/- 7 omega cm, 8%) and the parallel conductance of the surrounding tissues (7 +/- 6 ml, 10%). The mean difference was 3 +/- 2 ml (7%) for end-diastolic volume and 3 +/- 2 ml (11%) for end-systolic volume. Stroke volume and ejection fraction were also reproducible with mean difference of 2 +/- 1 ml (9%) and 3 +/- 2% (8%) respectively. The end-systolic pressure-volume relationships were nearly superimposable with the slope being 6.05 +/- 1.82 mmHg/ml on day 1 and 6.13 +/- 2.22 mmHg/ml on day 2. The difference averaged 0.63 +/- 0.42 mmHg/ml (11%). These results suggest that highly reproducible volume estimates by conductance catheter offer its feasibility of serial assessment of ventricular performance in vivo.

[An autopsy case of spinal subdural abscess in the aged--comparative study with neuroradiological findings]

An 82-year-old woman without previous medical problem noticed vague back pain on December 31, 1989, and was admitted to a hospital because she developed a fever, a rapidly progressive weakness followed by anesthesia of the lower extremities and sphincter disturbance. On myelography and myelo-CT, the spinal cord appeared to be displaced by an extramedullary mass which partially blocked the subdural space at the level of T-9 to L-1. When transferred to our hospital on January 8, 1990, she was febrile and complaining of headache with meningeal signs. Percussion tenderness was present at T-8 to L-1 spinal spinous process. Neurological examination revealed that the patient had mild consciousness clouding, total paraplegia in the legs, sensory disturbance of a partial degree at L-1 to L-3 and totally below L-3, brisk but equal tendon reflexes in the upper extremities, areflexia in the legs with positive bilateral Babinski signs and sphincter disturbance. Otherwise she was neurologically unremarkable. Acute inflammatory reactions were prominent among the laboratory findings on admission. A lumbar tap yielded purulent fluid with more than 170,000 cells/mm3, 5,000 mg/dl of protein, 44 mg/dl of glucose and culture of the fluid isolated Escherichia coli. T1-weighted sagittal MRI disclosed an ill defined mass which showed the same or locally higher with gadopentetate dimeglumine (Gd-DTPA) signal intensity as soft tissue, compressing the spinal cord anteriorly from T-7 to L-3. The lesion was noticed to have a more extensive rostral-caudal extent than was inferred from myelography and myelo-CT.(ABSTRACT TRUNCATED AT 250 WORDS)

Acute spinal epidural abscess and spinal leptomeningitis: report of 2 cases with comparative neuroradiological and autopsy study

A 21-year-old male developed back pain, fever, and rapidly progressive quadriparesis. Lumbar tap yielded frank pus which was confirmed on magnetic resonance imaging (MRI) to be located mainly in the cervical epidural space. Conservative antibiotic remedy was partially effective for restoration of the neurological deficits. A 82-year-old female noticed low-back pain which was rapidly accompanied with clouding of consciousness, paraplegia, and sphincter disturbances. Lumbar puncture revealed thick pus which was best depicted on MRI in the thoracolumbar subarachnoid space. At autopsy, spinal subarachnoid abscess or leptomeningitis was confirmed, and a spinal infarction previously unrecognized on MRI was found. Usefulness and shortcomings of MRI in the diagnosis of paraspinal infections are discussed.

Temperature and solvent effects on reaction centers from Chloroflexus aurantiacus and Chromatium tepidum

Temperature and solvent effects on reaction center structures were examined in two thermophilic photosynthetic bacteria, Chloroflexus aurantiacus and Chromatium tepidum, in order to gain insight into the interactions among the reaction center proteins and pigment systems. Thermal stability of the reaction centers was found to be proportional to the optimum growth temperature. Circular dichroism (CD) spectra in the 250-300 nm region indicated that thermal denaturation destroyed tertiary structures (helix-to-helix interactions or amino acid residue conformation) in the native reaction center, keeping helical structures intact. Absorption and circular dichroism spectral changes showed that alcohol denatured the so-called special pair and the accessory BChl a independently. The alcohol denaturation further indicates that the coordination between BChl a and amino acid residue in the protein is one of the important interactions maintaining the pigment organization of the reaction centers.

Collateral circulation as a marker of the presence of viable myocardium in patients with recent myocardial infarction

The relationship between the presence of viable myocardium and the extent of coronary collateral circulation to the infarct area was evaluated in 20 patients with a recent anterior myocardial infarction who had complete obstruction of the left anterior descending coronary artery. The viability of myocardial tissue was assessed by exercise thallium-201 myocardial scintigraphy, and the collateral circulation was angiographically evaluated by means of a collateral index ranging from 0 to 3. Patients were divided into two groups according to the presence (group 1, n = 10) or absence (group 2, n = 10) of viable myocardium in the perfusion territory of the infarct-related artery. The collateral index in group 1 was 2.5 +/- 0.5 (SD), which was significantly higher than the 0.7 +/- 0.8 in group 2. These findings indicate that the presence of ischemic but viable myocardium is intimately related to the development of collateral circulation in patients with myocardial infarction, and the existence of well-developed collateral channels predicts the presence of viable myocardium in the infarct area.

Cervical esophageal motility: evaluation with US in progressive systemic sclerosis

High-resolution ultrasound (US) showed that initial peristalsis propelled ingested soda smoothly and rapidly in 20 volunteers without symptoms who met both manometric and radionuclide esophageal scintigraphic (RES) criteria for normal motility. Twenty-eight patients with progressive systemic sclerosis were classified according to results of RES as follows: group 1, normal esophageal motility (three patients [11%]); group 2, hypomotility of the esophagus, excluding the cervical esophagus (18 patients [64%]); and group 3, hypomotility of the cervical esophagus (seven patients [25%]). In the seven patients of group 3, US demonstrated that an incomplete peristalsis sequence or a feeble peristalsis propelled the soda in a slow and/or to-and-fro motion with low velocities. In the other 21 patients (75%), the soda passed through the esophagus smoothly and rapidly. Retention of soda in the cervical esophagus was not limited to patients with hypomotility of the cervical esophagus. It is concluded that US is useful in evaluation of cervical esophageal motility.

Water vapor effects on optical characteristics in Ti:LiNbO(3) channel waveguides

This paper describes experimental studies on propagation loss and crosstalk of TM-polarized light in Ti-diffused Z-cut LiNbO(3) channel waveguides as a function of the water vapor content in the diffusion atmosphere. The dependence of surface roughness and crystal quality on the waveguide fabrication atmosphere is taken into consideration. In this study it is found that waveguides with low propagation loss (<0.2 dB/cm), low crosstalk (<-20 dB), and smooth surfaces can be fabricated by strictly controlling the water vapor content introduced into the oxygen or argon carrier gas.

Unilateral asterixis

We describe three patients with unilateral asterixis. One diabetic patient with a moderately-sized haematoma in the left putamen initially developed bilateral and symmetrical asterixis, which became confined to the right side as his diabetes mellitus was controlled. Two patients showed unilateral asterixis due to haematomas in the contralateral basal ganglia and thalamus, respectively. The present findings indicate that not only lesions of the thalamus but also those of the basal ganglia can cause unilateral asterixis, and bilateral and symmetrical asterixis does not necessarily exclude the presence of a focal mass lesion in the cerebrum.

Resonance Raman studies on the structure of bacteriochlorophyll c in chlorosomes from Chloroflexus aurantiacus

Resonance Raman spectra of chlorosomes isolated from the thermophilic green photosynthetic bacterium Chloroflexus aurantiacus have been obtained with several excitation wavelengths from 441.6 to 514.5 nm. Resonance Raman spectra of bacteriochlorophyll (BChl) c isolated from C. aurantiacus cells have also been observed. The C=C stretching frequencies of BChl c in the chlorosomes were found to be at 1,556 (strong) and 1,544 (shoulder) cm-1, which correspond to those expected for the 5-coordinated BChl c. The C-9 carbonyl resonance Raman frequency was found at 1,642 cm-1, indicating that this group is either hydrogen-bonded to an Mg-coordinated hydroxyl group or coordinated to the Mg ion.

Development of ophthalmoplegia in amyotrophic lateral sclerosis during long-term use of respirators

Patients with amyotrophic lateral sclerosis (ALS), who survive longer on a life-support system, exceeding the natural course of this disease, show new features of ALS. We report here a clinico-pathologic study of a 51-year-old patient with sporadic ALS who developed progressive external ophthalmoplegia 3 years after he remained on a respirator and died 5 years later, 13 years after the onset of his illness. The external ophthalmoplegia was initially accompanied by preserved doll's eye phenomenon, which later became absent. Autopsy revealed not only degeneration of the upper and lower motor neuron systems typical of ALS, but also degeneration of the Clarke's dorsal nuclei, spinocerebellar tracts, substantia nigra and inferior olives in addition to intracytoplasmic neuronal inclusion bodies in various areas. The oculomotor and abducens nuclei were variably involved, accompanied by neurogenic atrophy of the extraocular muscles. Our case report is consistent with the idea that ALS comprises a heterogeneous group of disorders, and also indicates that long-term use of respirators may make some patients with this illness prone to developing atypical clinical and neuropathologic features which are not observed during the natural course of ALS.

Force-time integral does not improve predictability of cardiac O2 consumption from pressure-volume area (PVA) in dog left ventricle

We have proposed the systolic pressure-volume area (PVA) as a measure of the total mechanical energy generated by ventricular contraction, and we found a closely linear correlation between PVA and cardiac oxygen consumption (VO2). Although the force-time integral (FTI) has long been considered to be the most reliable correlate of cardiac oxygen consumption (VO2), we have already shown that VO2 remained constant although FTI was changed while PVA was kept constant in the excised, cross-circulated dog left ventricle. This means that PVA is superior to FTI as a predictor of VO2. In the present study, we studied whether a linear addition of FTI to PVA could improve the prediction of VO2 from PVA in isovolumic and ejecting contractions with different afterload pressures in the same type of dog left ventricle preparation. Although left ventricular VO2 was always closely correlated with either PVA (r = 0.967, mean after z-transformation) or FTI (mean r = 0.925), multiple regression analysis indicated that PVA alone accounted for as much as 94% (mean) of the variance of VO2 and that FTI linearly added to PVA accounted for an additional few percent of the variance (statistically significant in less than half the cases). We conclude that the addition of FTI to PVA does not improve the predictability of VO2 from PVA in ordinary contractions.

Effects of bigeminies and paired-pulse stimulation on oxygen consumption in dog left ventricle

In 10 excised, cross-circulated, isovolumically beating dog left ventricles, we examined the effects of bigeminy, including paired-pulse stimulation, on cardiac oxygen consumption (VO2) and evaluated whether the VO2 versus pressure-volume area (PVA) relation obtained from regularly beating hearts in our previous studies could account for the changes in VO2 during bigeminies with various coupling intervals. The extrasystolic interval (ESI) was decreased in four steps from 300 msec (regular rhythm) to paired-pulse stimulation (less than or equal to 210 msec). The sum of ESI and the postextrasystolic interval was always held constant (600 msec); therefore, the number of excitations was 200/min at any ESI. Both VO2 and PVA were measured in four runs: a small volume run at a ventricular volume of 13 ml, a large volume of 12 ml, a calcium run in which contractility was enhanced by CaCl2 at a small volume of 12 ml, and a verapamil run in which contractility was depressed by verapamil at a large volume of 20 ml. In any run, both VO2 and PVA were unchanged at long ESIs (greater than or equal to 250 msec) from each control value at regular rhythm, but VO2 markedly increased at short ESIs (less than or equal to 230 msec). VO2s during bigeminies with various ESIs were comparable with the theoretical VO2 values that were calculated by the VO2-PVA relation at regular rhythm. However, the theoretical VO2 values underestimated the measured VO2 values at the shortest ESIs under a high volume loading and in a high contractile state. This indicates that the PVA concept can be expanded to various arrhythmias unless ESI becomes very short.