Search PubMed⌕ Search

Biomedical subjects

I Rubinstein

Publications and source records attributed to I Rubinstein.

At least 163 records · Page 9Linked to original sources
PubMed1988

Morphologic diagnosis of idiopathic pulmonary alveolar lipoproteinosis-revisited.

The usefulness of transbronchial biopsy in diagnosing idiopathic pulmonary alveolar lipoproteinosis (PAL) is not emphasized in the literature. Therefore, we decided to reassess our approach to the morphologic diagnosis of this disorder in 14 patients diagnosed over the past 13 years in two major teaching hospitals in Toronto. The morphologic diagnosis of idiopathic PAL was established by means of open lung biopsy in 11 patients; the use of transbronchial biopsy was not considered in eight of them. Transbronchial biopsy was performed in six patients, and the diagnosis of idiopathic PAL was reliably established in five cases. We conclude that transbronchial biopsy may be a worthwhile preliminary procedure to open lung biopsy in patients with suspected idiopathic PAL, and it can reliably establish the diagnosis in such cases.

Adolescent↗
PubMed1988

Fatal pulmonary emboli in hospitalized patients. An autopsy study.

To determine the accuracy of the antemortem diagnosis of major pulmonary embolism, we reviewed 1276 autopsy reports at St Michael's Hospital, Toronto, from 1980 to 1984. Of 44 patients identified with major pulmonary embolism as the cause of death or a major factor contributing to it, 14 (31.8%) had the diagnosis suspected before death. We could not find any distinctive features separating these patients from those in whom the diagnosis of pulmonary embolism was not suspected before death. We conclude that major pulmonary embolism is still underdiagnosed in hospitalized patients, despite the availability of lung scanning and pulmonary angiography.

Cause of Death↗
PubMed1987

Immediate and delayed bronchoconstriction after exercise in patients with asthma.

Although an immediate asthmatic response after exercise is known to occur in some patients with asthma, the existence of a delayed asthmatic response after exercise is controversial. Accordingly, we studied 53 patients who had an immediate mean (+/- SD) decrease in forced expiratory volume at one second (FEV1) of 36 +/- 13 percent, which was maximal 13 +/- 12 minutes after the completion of treadmill exercise. Eight of these patients also had a delayed asthmatic response (a 32 +/- 5 percent decrease in FEV1 occurring 5.0 +/- 1.8 hours after exercise). During a control day, on which the FEV1 was measured serially but no exercise was performed, the same delayed asthmatic response was observed in all but one patient. This finding suggests that the delayed asthmatic response observed in these patients after exercise was not specifically related to the performance of exercise. We conclude that in patients who have bronchoconstriction immediately after exercise, a second asthmatic response occurring later after the exercise is uncommon.

Adolescent↗
PubMed1987

Effects of bile acids on ventricular muscle contraction and electrophysiological properties: studies in rat papillary muscle and isolated ventricular myocytes.

The effects of sodium salts of various bile acids on the contractile force and the electrophysiological properties of rat ventricular muscle were studied in vitro. Primary, conjugated, and secondary bile acids were studied in a concentration range of 10(-9)-10(-6) mol/l, which corresponds to concentrations found in the plasma of patients with cholestatic jaundice. In general, the bile acid induced a negative inotropic effect which was manifested as a reduction in active tension, maximum rate of tension activation, and maximum rate of tension relaxation. Twitch duration and time to peak tension were unaffected by the bile acids. The negative inotropism was associated with a reduction in ventricular action potential duration. Resting potential, action potential amplitude, and maximum upstroke velocity of phase 0 depolarization were unaffected. Voltage clamp experiments in rat ventricular myocytes demonstrated that sodium taurocholate decreased the slow inward current and slightly increased the outward potassium current. Hence, these effects on the membrane currents are probably responsible for the negative inotropic effect.

Action Potentials↗
PubMed1987

Effects of thyroid hormone on the action potential and membrane currents of guinea pig ventricular myocytes.

We studied the effects of thyroid hormone on the action potential and membrane currents recorded from enzymatically dissociated guinea pig ventricular myocytes, by means of the whole-cell recording technique. Hypothyroidism was associated with an increase in action potential duration, whereas hyperthyroidism was associated with a decrease in duration. These effects are similar to those reported in multicellular preparations. Hypo- and hyperthyroidism were also associated with a decrease and an increase, respectively, in the slope of the action potential plateau. Resting potential and action potential amplitude were unaffected by the alterations in the thyroid state. The voltage-clamp experiments revealed that as compared with euthyroid myocytes, the peak calcium current was bigger in hyperthyroid myocytes and smaller in hypothyroid myocytes. The potassium outward current (at a membrane potential = 50 mV) was of similar amplitude in hypo- and euthyroid myocytes and bigger in hyperthyroid myocytes. Our major conclusion is that thyroid hormones regulate the amplitude of the calcium current and that this effect may be responsible in part for the modulation of myocardial contractility by thyroid hormones.

Action Potentials↗
PubMed1987

Aurothioglucose overdosage in five patients with rheumatoid arthritis.

Five patients with active seronegative, rheumatoid arthritis, HLA-DR3 negative, received inadvertently 250 to 500 mg of aurothioglucose instead of their usual weekly dose, during standard remission-inducing chrysotherapy. Subsequently a rapid and sustained clinical remission appeared in all five patients.

Adult↗
PubMed1987

Electrophysiological effects of a novel antiarrhythmic drug, EO-122, on guinea pig ventricular muscle and isolated myocytes.

EO-122, a newly developed structural analog of lidocaine, has recently been shown to suppress ventricular arrhythmias in a few clinical studies in patients and in experimental animals. In the present study, we investigated the effects of EO-122 on the electrophysiological properties of guinea pig papillary muscle and ventricular myocytes by means of standard microelectrode and whole-cell recording techniques, respectively, At the concentration range of 10(-7)-10(-4) M (cycle length, 2000 ms), resting potential and action potential duration (APD90) were not altered by the drug. Action potential amplitude and APD50 were reduced (p less than 0.01) by 10(-4) M, and Vmax was reduced (p less than 0.01) by EO-122 greater than or equal to 10(-5) M. The effect of EO-122 on Vmax was use-dependent. At 10(-6) and 10(-5) M (cycle length, 2000 ms), the time constant for onset of block (tau on) was 37.0 +/- 13.2 and 26.0 +/- 3.4 s, respectively. The recovery kinetics from use-dependent block was not monoexponential, and the estimated "time constant" for recovery was 76.5 s. We examined the effects of EO-122, 10(-5) M, on the membrane currents in ventricular myocytes and found that the drug attenuated the slow inward current (Isi). EO-122 reduced peak Isi by 68.6 +/- 5.2% (p less than 0.005), whereas the outward current was unchanged. The present study demonstrates that EO-122 blocks both the fast inward (Na+) and the slow inward (Ca2+) channels, and these effects are probably responsible for the antiarrhythmic effects of the drug.

Action Potentials↗
PubMed1987

Effect of sodium pentobarbital on the transmembrane action potential and the slow inward current of guinea pig ventricular myocytes.

Barbiturates, which are widely used in clinical anesthesia, exert a negative inotropic effect on the myocardium. To investigate the mechanism for the negative inotropism, we studied the effect of sodium pentobarbital (SP) on the action potential and the slow inward current recorded from guinea pig ventricular myocytes. We found that SP at 0.6, 1.0, and 1.6 microM decreased action potential duration at 50% repolarization by 17 +/- 6, 25 +/- 11, and 29 +/- 8%, respectively (p less than 0.05, n = 4). At the concentration range of 0.6-1.6 microM, resting potential and action potential amplitude were unaffected. Voltage-clamp studies in ventricular myocytes demonstrated that SP at 0.6, 1.0, and 1.6 microM reduced the peak slow inward current by 30 +/- 4, 36 +/- 14, and 67 +/- 5%, respectively (p less than 0.005, n = 4). In conclusion, SP, a frequently used anesthetic, decreases the slow inward current in guinea pig ventricular myocytes at clinically relevant concentrations.

Action Potentials↗
PubMed1987

Sarcoidosis versus foreign-body granulomas.

A 42-year-old man developed a papulonodular exanthema 10 years following an injury from a shell explosion. The differential diagnosis between sarcoid-like, foreign-body granulomas and Boeck's sarcoid was inconclusive by histology, but x-ray spectroanalytic examination revealed silicon particles within the epitheloid cell granulomas.

Adult↗
PubMed1987

An isovolume method for analysis of density dependence of maximal expiratory flows.

The usual method of measuring density dependence of maximum expiratory flows is superimposition at total lung capacity or residual volume of maximum expiratory flow volume (MEFV) curves obtained breathing air and a mixture of 80% He plus 20% O2 (HeO2). A major problem with this technique is the large variability in results, which has been thought to be due to errors in matching lung volumes on both gases. Accordingly, we obtained MEFV curves breathing air and HeO2 using a bag-in-the-box system so that the curves breathing the two gas mixtures could be directly superimposed without removing the mouthpiece (isovolume). Ten healthy, nonsmoking subjects performed MEFV curves on each gas mixture for six consecutive experiments. We compared the increase in flow at 50% of vital capacity (delta Vmax50) and volume of isoflow (Viso) by superimposing and matching the MEFV curves at total lung capacity, at residual volume, and using the isovolume method. The variability of each method was assessed by the mean intersubject and intrasubject coefficients of variation. In all subjects, the mean delta Vmax50 and Viso as well as their corresponding coefficients of variation were not significantly different among the three methods. We conclude that, in healthy nonsmoking young adults, the method chosen for superimposing and matching MEFV curves has no effect on the variability of delta Vmax50 and Viso.

Adult↗
PubMed1987

Effect of mouthpiece, noseclips, and head position on airway area measured by acoustic reflections.

To investigate whether it is possible to simplify the methodology of measuring airway area by acoustic reflections, we measured upper airway area in 10 healthy subjects during tidal breathing according to seven different protocols. Three protocols employed custom-made bulky mouthpiece with or without nose-clips, two protocols used a scuba-diving mouthpiece and cotton balls placed in the nostrils instead of noseclips, and two protocols employed neck flexion and extension. We found no significant difference in average pharyngeal, glottic, and tracheal areas for any of the protocols except for neck flexion, which was associated with a significantly lower mean pharyngeal area. Intraindividual variabilities were comparable for all protocols, except for protocol employing the customary bulky mouthpiece and no noseclips, which consistently resulted in the most variable measurements of area for all three airway segments: pharynx, glottis, and trachea. Furthermore, we found that the protocol employing the scuba-diving mouthpiece with or without cotton balls in the nostrils resulted in the lowest number of unacceptable measurements. We conclude that measurements of airway area by acoustic reflections may be further simplified by using a scuba-diving mouthpiece without noseclips; furthermore, control of head position during measurements is not critical provided there is no obvious neck flexion.

Acoustics↗
PubMed1986

Sarcoidosis of the penis: report of a case.

We report a case of sarcoidosis identified histologically as the cause of chronic painful erythematous induration of the penis with several subcutaneous nodules and cutaneous ulceration. The lesions improved in response to topically applied corticosteroids but they reappeared later and persisted despite treatment. We suggest that sarcoidosis, although rare, should be considered in the differential diagnosis of any chronic lesion involving the penis in adults.

Humans↗