Biomedical subjects
Publications and source records attributed to W M Anderson.
We evaluated the effects of diaphragmatic fatigue on muscle phosphatidylinositol phosphate (PIP) metabolism. Results revealed that the total PIP pool was 76% greater in fatigued rat diaphragms compared to controls, which suggests that fatigue was associated with inhibition of sarcolemmal membrane bound PIP hydrolysis.
The effect of chronic cocaine administration on norepinephrine stimulated hydrolysis of inositol 1,4,5-trisphosphate from the membrane phosphatidylinositol phosphate pool in isolated rat aorta was investigated. Rats received saline (controls), or 10 or 20 mg/kg cocaine once a day for 15 days. This treatment resulted in a dose-dependent reduction in norepinephrine (0.36 microM) stimulated phosphoinositide hydrolysis. The effect of acute cocaine was determined by adding 30 microM cocaine to the in vitro incubation solution. When aortas were exposed to cocaine and norepinephrine simultaneously, in vitro, inositol phosphate formation doubled. By itself, cocaine did not affect phosphoinositide hydrolysis. Contraction of aortic helical strips by norepinephrine decreased in tissues from rats chronically treated with 20 mg/kg cocaine. In vitro cocaine shifted the norepinephrine concentration/response curve to the left and increased the maximum response. Neither acute nor chronic cocaine treatment affected prazosin's apparent dissociation constant, suggesting that cocaine did not affect receptor affinity. These data suggest that chronic, but not acute cocaine administration may interfere with pharmacomechanical coupling in rat aorta.
The measurement of oxygenation during sleep has become a standard procedure in the assessment of hypoxemia in patients with various disorders. However, an accepted method for quantitating this hypoxemia is not available. This study describes the development of computerized data acquisition and analysis programs to quantitate nocturnal hypoxemia in patients with sleep and breathing disorders. The acquisition program samples the voltage output from pulse oximeters used to measure oxyhemoglobin saturation (SpO2) and stores this on an IBM PC or compatible computer. The analysis program integrates the SpO2 over time below the patient's pretest baseline as well as the integral below 90, 80, 70, 60 and 50% saturation. We refer to each integral as Saturation Impairment Time or SIT. In order to compare these integrals between patients or between the same patient but different studies, the integral is divided by the total sleep study time. We refer to each of these integrals, corrected for sleep study time, as the SIT index. Evaluation of the SIT index in 10 consecutive patients referred for various sleep disorders revealed acquisition program detection and deletion of 48 of 57 (86%) oximeter probe artifacts (mean duration of 3 seconds for undetected artifacts). There were no significant artifacts in the analysis program calculation of the SIT index in these same patients. In conclusion, computer programs were developed to measure and quantitate oxygen saturation measured by oximeters. Preliminary results reveal an accuracy of measurement which should prove acceptable in further clinical evaluations.
The effects of zero extracellular Ca2+ on the contractility of rat diaphragmatic strips in vitro were studied in conjunction with various pharmacological agents known to influence the intracellular Ca2+ concentration: the Na+ ionophore, monensin, and the Na(+)-K+ pump inhibitor, ouabain, which enhance [Ca2+]i, caffeine, which induces Ca2+ release from the sarcoplasmic reticulum (SR), and ryanodine, which prevents Ca2+ retention by the SR. The effect of increasing [Ca2+]i on diaphragmatic contraction was assessed by comparing contractions induced by 120 mM K+ in the small muscle strips before and after the addition of ouabain or monensin. Monensin (20 microM) and ouabain (1-100 microM) augmented contractions up to threefold. Treatment of diaphragm strips with 3 nM ryanodine increased baseline tension 360% above the original resting tension but only if the diaphragm was electrically stimulated concurrently; 100 microM ryanodine induced contracture in quiescent tissue. High K+ contractures were of greater magnitude in the presence of ryanodine compared with control, and relaxation time was prolonged by greater than 200%. Ca(2+)-free conditions ameliorated these actions of ryanodine. Ryanodine reduced contractions induced by 10 mM caffeine and nearly abolished them in Ca(2+)-free solution. The data demonstrate that extracellular Ca2+ is important in certain types of contractile responses of the diaphragm and suggest that the processes necessary to utilize extracellular Ca2+ are present in the diaphragm.
Two cationic, lipophilic laser dyes, 1,1',3,3,3',3'-hexamethylindodicarbocyanine iodide (HIDC) and 1,1',3,3,3',3'-hexamethylindotricarbocyanine iodide (HITC), inhibit bovine heart mitochondrial and Paracoccus denitrificans NADH oxidase activities. The mitochondrial I50 values were 0.5 microM (HIDC) and 1.2 microM (HITC), and the P. denitrificans I50 values 1.2 microM (HIDC) and 1.5 microM (HITC). Neither succinate nor cytochrome oxidase (EC 1.9.3.1) activities were inhibited significantly by either compound, localizing the site of inhibition to the segment of each electron transport chain between NADH and ubiquinone. With submitochrondrial particles (SMP), NADH-dependent reduction of menadione, duroquinone and coenzyme Q1 was inhibited markedly (HIDC was the more potent inhibitor). Using purified complex I, only NADH-dependent reduction of duroquinone and coenzyme Q1 was inhibited markedly (HIDC was the more potent inhibitor) and reduction of menadione was inhibited slightly. With P. denitrificans membrane vesicles, NADH-dependent reduction of menadione, juglone, and coenzyme Q1 was inhibited slightly and duroquinone reduction was inhibited markedly. Membrane-dependent interactions appear to be involved, since the compounds were more inhibitory with membrane preparations than with complex I. The mechanism of inhibition (except for the HIDC effect on coenzyme Q1 reduction with P. denitrificans) appeared to be through the interaction of dye with the rotenone site on NADH-ubiquinone reductase (EC 1.6.99.3), since rotenone-insensitive preparations of complex I and P. denitrificans membrane vesicles were also insensitive to HIDC and HITC inhibition.
Extracellular Ca2+ has been shown to be important for the normal function of the diaphragm. In this study we have examined the potential importance of Na(+)-Ca2+ exchange as a mechanism for Ca2+ influx during the contractile process by studying the effect of inhibition or stimulation of Na(+)-Ca2+ exchange. Blockade of Na(+)-Ca2+ exchange with amiloride attenuated the twitch response, altered the force-frequency response curve, and enhanced the development of fatigue. The effect of amiloride could be partially reversed by increasing the extracellular Ca2+ concentration. The ability of amiloride to decrease force was associated with decreased Ca2+ uptake by the diaphragm. Enhancing intracellular Na(+)-extracellular Ca2+ exchange by inhibiting the Na(+)-K+ pump significantly decreased the rate of the development of muscle fatigue (89%). The maximal inhibition of diaphragmatic force produced by the amiloride analogue benzamil, which possesses 10-fold greater selectivity for Na(+)-Ca2+ exchange, was not significantly different from that produced by amiloride (76.2 +/- 1.1%), with a concentration that decreased maximum force by 50% equal to 46 microM compared with 460 microM for amiloride. Both agents slowed the maximal rate of relaxation up to 90%. Benzamil elevated resting tension during continuous stimulation of the diaphragm at 0.15 Hz. The results suggest that Na(+)-Ca2+ exchange may have a role in the normal function of the diaphragm.
It has been suggested that spirometry should be incorporated into the routine examination of every patient, analogous to obtaining vital signs. To determine the impact of spirometry on the management of outpatients with respiratory disease, spirometry was performed on 150 consecutive patients (123 men and 27 women, mean age 57 +/- 12 years) seen in our pulmonary disease outpatient clinics. Patients with obstructive (n = 75), restrictive (n = 31), mixed (n = 26) or other respiratory diseases (n = 18) were initially assessed by history and physical examination and classified as improved, stable, or worse compared to previous visits. A clinical management plan (CMP) was formulated based on this initial evaluation. Spirometric results were then made available to the examiner who could then make changes in the proposed CMP. The addition of spirometric results caused alteration of the CMP in only eight (5 percent) patients; in the remaining 142 patients, results did not affect the CMP. Two clinical findings identified those patients whose CMP was most likely to be altered by spirometry: severity of lung dysfunction (determined from previous spirometry) and deterioration of clinical status (judged by history and physical examination). Of the eight patients whose CMP was changed after review of spirometry, six (75 percent) had previous severe ventilatory dysfunction (FEV1 or FVC less than or equal to 40 percent of predicted or FEV1/FVC ratio less than or equal to 0.40). In 6 of 38 patients (16 percent) with severe ventilatory dysfunction, CMP was altered after spirometry while only 2 of 112 patients (1.8 percent) with mild or moderate dysfunction had changes in their CMP. Patients who were clinically assessed as worse compared to their previous visit were more likely to have their CMP altered after review of spirometry when compared to those considered improved or stable by a ratio of 6:1. These results suggest that spirometry is most likely to supplement the physician's history and physical examination in the management of outpatients with pulmonary disease when the initial evaluation suggests that the patient has clinically deteriorated since the previous clinic visit, or when he or she has previous severe ventilatory dysfunction.
The presentations of mycoplasmal pneumonia can be varied and sometimes complicated. The atypical nature of this illness, as opposed to the clear pattern of findings in classic bacterial pneumonias, leads the physician to the diagnosis. Appropriate therapy then allows quick improvement as a rule, with few sequelae.
The ability of the rat diaphragm to produce inositol 1,4,5-trisphosphate (InsP3) in response to a maximal contractile stimulus was determine in vitro in both fatigued and nonfatigued diaphragms. InsP3 was produced during a maximal contraction of the diaphragm. After inducing fatigue, there was a significant reduction in the production of InsP3 compared with that in nonfatigued muscle. The maximal force generated by the diaphragm was also decreased after fatigue. A significant positive linear correlation was found between the force developed by the diaphragm and the amount of InsP3 liberated.
Two ventilator dependent patients developed tracheoesophageal fistulas. Their subsequent treatment using high frequency jet ventilation resulted in transient clinical improvement. Risk factors for the development of tracheoesophageal fistulas in intubated patients are discussed and preventive measures are outlined. High frequency jet ventilation may be useful in managing these patients by preventing death from respiratory failure and allows time for definitive therapy.
Mucoid impaction is a complication of asthma and is frequently recurrent in patients with allergic bronchopulmonary aspergillosis (ABPA). This report describes a patient with asthma and recurrent bilateral well-circumscribed densities on chest roentgenogram in the absence of ABPA. Recognition of this clinical presentation may avoid the need for invasive diagnostic procedures or steroid therapy.
The binding of porcine heart mitochondrial malate dehydrogenase and beta-hydroxyacyl-CoA dehydrogenase to bovine heart NADH:ubiquinone oxidoreductase (complex I), but not that of bovine heart alpha-ketoglutarate dehydrogenase complex, is virtually abolished by 0.1 mM NADH. The malate dehydrogenase and beta-hydroxyacyl-CoA enzymes compete in part for the same binding site(s) on complex I as do the malate dehydrogenase and alpha-ketoglutarate dehydrogenase complex enzymes. Associations between mitochondrial malate dehydrogenase and bovine serum albumin were observed. Subtle convection artifacts in short-time centrifugation tests of enzyme association with the Beckman Airfuge are described. Substrate channeling of NADH from both the mitochondrial and cytoplasmic malate dehydrogenase isozymes to complex I and reduction of ubiquinone-1 were shown to occur in vitro by transient enzyme-enzyme complex formation. Excess apoenzyme causes little inhibition of the substrate channeling reaction with both malate dehydrogenase isozymes in spite of tighter equilibrium binding than the holoenzyme to complex I. This substrate channeling could, in principle, provide a dynamic microcompartmentation of mitochondrial NADH.
1. Dequalinium chloride (DECA) and three related quinolinium compounds inhibit bovine heart mitochondrial and Paracoccus denitrificans electron transport activity, with inhibition localized between NADH and ubiquinone in both electron transport chains. 2. Structure-activity studies reveal that two quinolinium rings and a long bridging group are necessary for significant inhibition of reduction of artificial electron acceptors and coenzyme Q, whereas only one quinolinium ring and a long hydrocarbon side chain are required for significant inhibition of NADH oxidase activity. 3. Inhibition of coenzyme Q reduction by DECA is not reversed by dialysis. 4. Studies comparing DECA inhibition of rotenone-sensitive with rotenone-insensitive preparations indicate that DECA acts by a different inhibitory mechanism than rotenone on mammalian mitochondrial and P. denitrificans NADH----ubiquinone reductase.
A 52-year-old man was admitted to the General Surgical Service, with acute onset of left back and flank pain. Two weeks prior to admission he had been subjected to a 3G to 4G acceleration in an ejection seat training simulator. On the day of admission, he had performed a 100 yard swim in flight gear following a seven foot jump into water. He denied any injury during the above exercises or any other trauma. A falling hematocrit was demonstrated by serial determinations and a computerized tomography scan revealed a left retroperitoneal hematoma with normal bilateral renal function and no obvious renal injury. Continued hemorrhage resulted in laparotomy, which showed an 11 cm left adrenal tumor with massive hemorrhage into the retroperitoneum. Histologically the tumor was a benign non-functioning adrenal cortical adenoma.
To determine the significance of an isolated reduction in residual volume (RV), the medical records and chest radiographs of 69 patients who had a RV less than or equal to 65% of predicted and normal VC, DLCO, and expiratory flow rates were reviewed. Sixty-three of 69 patients (92%) had clinical conditions that could account for their decreased RV. Definite disease was considered to be present in the 39 patients with radiographically apparent parenchymal (n = 18) or chest wall (n = 21) abnormalities, whereas 24 others with clinical diagnoses such as congestive heart failure or toxic inhalation were considered to have probable disease. All patients who had a RV below 50% of predicted had either definite or probable disease. Follow-up testing of 19 patients 31 +/- 21 months after their initial reduction in RV was first documented indicated that the RV accurately reflected the patient's current clinical status in that it increased by 17 +/- 16% of predicted in those who were clinically improved and decreased by 27 +/- 7% in those who were clinically worse. In patients who were clinically stable, the isolated reduction in RV was a persistent finding. We conclude that an isolated reduction in RV is a clinically significant finding indicative of pulmonary or chest wall disease. Interval changes in RV reflect alterations in disease activity.
Older anticholinergic agents such as stramonium and atropine have significant non-pulmonary effects. The non-pulmonary effects of a new quaternary anticholinergic, ipratropium bromide, have been studied both in the United States and abroad; these effects include inhibition of salivation, interference with micturition, and ocular effects such as pupil size, visual acuity, and intraocular pressure. Hemodynamic effects such as heart rate, blood pressure, and blood gas changes have also been studied. These evaluations have been performed in animals and in healthy and sick human subjects, following administration of ipratropium parenterally and by inhalation in a variety of dosage ranges. Ipratropium, a muscarinic inhibitor, would be expected to have effects similar to those of atropine. The most conspicuous result of these studies has been the low incidence of significant changes, even at high dose levels, when ipratropium bromide is administered by inhalation.
Bovine heart mitochondrial NADH----ubiquinone reductase (complex I), contains two disulfide-linked subunits of 75 and 33 kDa as revealed by two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis with beta-mercaptoethanol omitted from preparation of the sample for the first dimension. Two unidentified polypeptides (110-115 and 69 kDa) are also found in disulfide linkage with the two complex I subunits. The 110-115-kDa polypeptide appears to be pyridine dinucleotide transhydrogenase by several criteria including selective precipitation with an antibody raised to the purified transhydrogenase. The two disulfide-linked subunits were also found in a product cross-linked for 2 min with dithiobis (succinimidyl propionate) (DSP) along with five other complex I subunits of 53-57, 42, 24-27, 17-18, and 12.5-15.5 kDa (Gondal, J.A., and Anderson, W.M. (1985) J. Biol. Chem. 260, 5931-5935) indicating that these seven subunits lie within 11-12 A of each other at one or more points in space in the enzyme's interior. Cross-linking of complex I with DSP for 2 min in the presence of 1 microM rotenone yielded a cross-linked product consisting of the two natural disulfide-linked subunits and the 110-115- and 69-kDa polypeptides. This suggests that rotenone induces a conformational change in the enzyme that moves the seven DSP cross-linked subunits away from each other and outside the 11-12 A bridging distance of DSP. This alteration in conformation may be communicated to iron-sulfur center N-2 within the hydrophobic outer shell of the enzyme to prevent electron transfer to its natural electron acceptor, ubiquinone. A model of rotenone action based upon these observations is presented.
The molecular morphology of NADH-ubiquinone reductase (complex I) was investigated by cross-linking with the cleavable bifunctional reagent, dithiobis(succinimidyl propionate). Cross-linking inhibits the following activities of the complex--NADH----3-acetylpyridine adenine dinucleotide (oxidized), NADH----2,6-dichloroindophenol, NADH----ferricyanide, and NADH----menadione--to different degrees with the greatest inhibition occurring with either ferricyanide or 3-acetylpyridine adenine dinucleotide as electron acceptor. Addition of 150 microM NADH affords partial protection from inhibition. Cross-linking quenches the FMN fluorescence of complex I (288 nm excitation/515 nm emission), and addition of 150 microM NADH greatly reduces the quenching. Treatment of complex I (1 mg/ml) for 2 min with dithiobis(succinimidyl propionate) (0.2 mg/ml) at 4 degrees C revealed a cross-linked product consisting of the following seven subunits: 75-80, 53-57, 42, 33-35, 24-27, 17-18, and 12.5-15.5 kDa. Five minutes of treatment cross-linked the unidentified polypeptides of 69 and 51 kDa to six of the seven complex I subunits, but the 12.5-15.5-kDa subunit may be missing from this cross-linked product, while 15 min of treatment cross-linked additional unidentified polypeptides of 177, 107, 72, and 63 kDa. Since longer times of cross-linking result in a larger number of unidentifiable polypeptide spots, the shorter cross-linking time results are taken as a more accurate picture of the native enzyme conformation. This would indicate that within complex I the following subunits are within 12 A of each other at one or more points in space: 75-80, 53-57, 42-45, 33-35, 24-27, 17-18, and, perhaps, 12.5-15.5 kDa. These subunits represent portions of all three fractions of the enzyme, i.e. flavoprotein, iron-protein, and insoluble or hydrophobic fractions.