New concepts in brachytherapy dosimetry.
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Brachytherapy↗
Biomedical subjects
M Cohen
Publications and source records attributed to M Cohen.
A simple method for the rapid determination of the stereospecificity of NAD-dependent dehydrogenases applied to mammalian IMP dehydrogenase and bacterial NADH peroxidase.
The stereospecificity of IMP dehydrogenase (IMP:NAD+ oxidoreductase, EC 1.1.1.205) from two different sources was determined. The enzyme preparations were obtained from murine lymphoblasts and from Escherichia coli. Both enzymes transferred the 2-3H of IMP to the pro-S position of carbon atom C-4 of the nicotinamide ring in NAD. Thus, B-sided stereospecificity is common to the enzyme from two very different species. In addition, the studies described here demonstrate that alcohol dehydrogenase and NADH peroxidase, used as auxiliary enzymes, in combination with a microdistillation procedure, should permit rapid determination of the stereospecificity of any NAD-dependent dehydrogenase for which the appropriate tritiated substrate is available.
Alcohol Dehydrogenase↗
Detection of activation of the contact system of coagulation in vitro and in vivo: quantitation of activated Hageman factor-C-1-inhibitor and kallikrein-C-1-inhibitor complexes by specific radioimmunoassays.
Radioimmunoassays (RIAs) for the detection of C-1-inhibitor (C-1-Inh) complexed to either kallikrein or activated Hageman factor (factor XIIa) are described. Kallikrein-C-1-Inh or factor XIIa-C-1-Inh complexes were bound to Sepharose to which monospecific antibodies against (pre)kallikrein or factor XII, respectively, were coupled. Bound complexes were subsequently detected by an incubation with affinity purified 125I-labeled antibodies against C-1-Inh. These RIAs were used to detect activation of the contact system of coagulation in vitro and in vivo. Addition of dextran sulfate (DXS) (20 micrograms/ml) to fresh plasma resulted at 37 degrees C in the rapid generation of amidolytic kallikrein activity, which was maximal after 1 to 2 min of incubation and subsequently decreased within a few minutes. The generation of kallikrein activity coincided with the appearance of both kallikrein-C-1-Inh and factor XIIa-C-1-Inh complexes. However, in contrast to kallikrein activity, both types of complexes remained detectable in the incubation mixtures during the incubation period. Experiments with purified kallikrein. C-1-Inh and partly purified beta-factor XIIa, and activation experiments in plasmas deficient in either factor XII or prekallikrein, demonstrated the specificity of both RIAs. The minimal amount of DXS that resulted in the generation of measurable amounts of both types of complexes in plasma was 2-3 micrograms per ml. Similar experiments with kaolin showed that with limiting amounts of activator (1-2 mg/ml), only kallikrein-C-1-Inh complexes were detected in plasma. When larger amounts of kaolin were added to plasma, factor XIIa-C-1-Inh complexes were additionally detected in plasma.(ABSTRACT TRUNCATED AT 250 WORDS)
Blood Coagulation↗
Thymic hypoplasia associated with isotretinoin embryopathy.
A newborn had isotretinoin embryopathy, including thymic hypoplasia. Evaluation of her immune functions demonstrated progressive attrition of T cells over the nine weeks until her death due to pneumonia. These studies strongly suggest an insult by isotretinoin to the immune system. Immune abnormalities may predispose infants with isotretinoin embryopathy to infection and contribute to their high mortality.
Abnormalities, Drug-Induced↗
Reconstruction of infected median sternotomy wounds.
Infected median sternotomy represents a major complication of cardiac surgery, with significant morbidity and mortality. The treatment of choice is immediate drainage and closure over suction irrigation catheters. However, when this conservative approach fails or radical debridement makes primary closure impossible, muscle flap closure is indicated. This form of reconstruction facilitates the obliteration of large mediastinal wounds; prevents spreading of infection on the heart, suture lines, grafts, or prosthetic material; and significantly decreases morbidity and mortality. We performed muscle flap closure in 11 consecutive patients in whom conservative treatment of infected median sternotomy wounds failed. All patients required closure with at least two muscle flaps or omentum for the complete obliteration of the mediastinal wounds. There was one postoperative death in our series due to acute heart failure. There were two superficial skin losses requiring skin grafting and one persistent draining sinus after reconstruction. Based on our experience and that of others, we conclude that muscle flap reconstruction should be considered as an important technique for the reconstruction of infected median sternotomy wounds.
Cardiac Surgical Procedures↗
Shoulder flap for head and neck reconstruction: an alternative when everything else fails.
The use of axial and free flaps made the use of delayed random flaps for the reconstruction of the head and neck almost obsolete. Immediate reconstruction of intraoral defects using the pectoralis major musculocutaneous flap primarily, as well as other axial or free flaps, has become a common practice. However, in some selected cases due to failure of previous operations or complications of radiation and recurrence, the reconstructive surgeon is left with very little choice. The purpose of this paper is not to advocate the use of the shoulder flap as a primary reconstructive procedure, but to call attention to its availability for certain complicated cases and briefly described the details of the technique.
Follow-Up Studies↗
Airborne and groundbased spectrophotometry of comet P/Halley from 5-13 micrometers.
Spectrophotometry from 5-10 micrometers (delta lambda/lambda approximately 0.02) of comet Halley was obtained from the Kuiper Airborne Observatory on 1985 December 12.1 and 1986 April 8.6 and 10.5, UT. 8-13 micrometers data were obtained on 17.2 December 1985 from the Nickel Telescope at Lick Observatory. The spectra show a strong broad emission band at 10 micrometers and a weak feature at 6.8 micrometers. We do not confirm the strong 7.5 micrometers emission feature observed by the Vega 1 spacecraft. The 10 micrometers band, identified with silicate materials, has substructure indicative of crystalline material. The band can be fitted by combining spectra data from a sample of interplanetary dust particles. The primary component of the silicate emission is due to olivine. The 6.8 micrometers emission feature can be due either to carbonates or the C-H deformation mode in organic molecules. The lack of other emission bands is used to place limits on the types of organic molecules responsible for the emission observed by others at 3.4 micrometers. Color temperatures significantly higher than the equilibrium blackbody temperature indicate that small particles are abundant in the coma. Significant spatial and temporal variations in the spectrum have been observed and show trends similar to those observed by the spacecraft and from the ground. Temporal variability of the silicate emission relative to the 5-8 micrometers continuum suggests that there are at least two physically separated components of the dust.
Astronomical Phenomena↗
The relative bioavailability of levonorgestrel and ethinylestradiol when administered in tablet and capsule form.
The relative bioavailability of levonorgestrel (LNG) and ethinylestradiol (EE2) administered as a conventional tablet (150/30) or capsule has been assessed in a randomized two-period crossover study in 9 healthy volunteer women. Serum concentrations were monitored for 24h post-dosing. There was no significant difference in any of the pharmacokinetic parameters determined for either steroid. Hence the relative bioavailability is similar after tablet and capsule formulations.
Adolescent↗
Evaluation of renal angiomyolipoma by traditional and modern imaging in a case of tuberous sclerosis.
Renal angiomyolipoma is known to affect mainly patients with tuberous sclerosis, although it can be found in a significant number of otherwise normal individuals. Few cases have been published in which angiomyolipoma and renal cell carcinoma occurred in the same kidney. In such cases the radiologist may be asked if it is possible to distinguish between the two tumors in the same kidney. The present case report describes systemic traditional and modern imaging of huge bilateral angiomyolipoma in tuberous sclerosis. The analysis of the data implies that, although the diagnosis of angiomyolipoma can be established with noninvasive techniques only, it is impossible to distinguish between the two mentioned tumors if they coexist in the same kidney, even if all available imaging techniques are used.
Adult↗
Bradycardia during elevation of a zygomatic arch fracture.
A case of bradycardia occurring during elevation of a zygomatic arch fracture is reported and possible mechanisms for the phenomenon are discussed. This case report serves to alert oral and maxillofacial surgeons and anesthesiologists to a possible hazard during surgical elevation of a fractured zygomatic arch.
Adult↗
Repair of right ventricular free wall defect with a pedicled muscle flap.
A unique case of repair of a full-thickness cardiac defect and simultaneous reconstruction of an infected median sternotomy wound is presented. A right ventricular defect, 6 cm in diameter, was closed with a fascia lata graft and reinforced with a rectus abdominis muscle flap. The superior portion of the mediastinum was obliterated with a pectoralis major muscle flap. The patient tolerated the procedure well and remains free of cardiac symptoms seven months postoperatively, with no evidence of residual infection.
Cardiac Surgical Procedures↗
Intramural hematoma of duodenum following endoscopic intestinal biopsy.
We present the fourth case to be reported in the literature of intramural hematoma of the duodenum following endoscopic small bowel biopsy. It is the first reported to have been diagnosed by ultrasonography and confirmed by contrast roentgenograms. Conservative treatment was effective in achieving satisfactory resolution of the obstruction within seven days, as evidenced by barium meal examination. The mechanism of trauma, in light of the other cases reported in the literature, is discussed.
Biopsy↗
Congenital embryonal rhabdomyosarcoma of the hand and Apert's syndrome.
A unique case of congenital embryonal rhabdomyosarcoma of the hand in a patient with Apert's syndrome is presented. Immediately after birth a 1 cm soft, bluish mass of the right thenar eminence was clinically diagnosed as a hemangioma. Several months later when the lesion started rapidly enlarging the nature of the tumor was identified, and it was treated with a multidisciplinary approach that included surgical resection, chemotherapy, and radiation.
Acrocephalosyndactylia↗
Prospective analysis of electrocardiographic variables as markers for extent and location of acute wall motion abnormalities observed during coronary angioplasty in human subjects.
To assess the usefulness of different electrocardiographic variables as markers for the presence, extent and location of new wall motion abnormalities seen after sudden controlled coronary occlusion, 23 patients with isolated left anterior descending (n = 12), or right (n = 11) coronary artery disease and a normal baseline left ventriculogram were prospectively studied during transluminal coronary angioplasty. A simultaneous 12 lead electrocardiogram was recorded before passing the balloon catheter and again at 30 seconds into the fourth inflation cycle. Using a second arterial catheter, a left ventriculogram was obtained at 40 seconds into the fourth inflation cycle. The extent of wall motion abnormalities was described as the percent of left ventricular perimeter showing hypocontractility. During balloon inflation, 19 of the 23 patients developed new hypocontractility ranging from 3 to 40%. ST segment elevation in lead V2 was the most sensitive marker for anterior wall hypocontractility and ST segment elevation in lead III was the most sensitive marker for inferior wall hypocontractility. Highly significant correlations were observed between the extent of the hypocontractile perimeter and 1) the sum of ST segment elevation in all 12 leads; 2) the magnitude of ST segment elevation in either lead V2 or lead III; and 3) the total number of leads with ST elevation greater than or equal to 0.5 mV. No significant changes were seen in the sum of R wave amplitudes, but a significant prolongation of the QT interval was seen during ischemia. In conclusion, acute ST segment elevation parallels the development of new asynergy during transluminal coronary angioplasty.(ABSTRACT TRUNCATED AT 250 WORDS)
Acute Disease↗
Comparison of single plane videodensitometry-based right ventricular ejection fraction in right and left anterior oblique views to biplane geometry-based right ventricular ejection fraction.
To evaluate the reliability of the videodensitometric assessment of right ventricular ejection fraction, 38 patients were studied during diagnostic cardiac catheterization. Digital subtraction images of the right ventricle were obtained in both the right anterior oblique and the left anterior oblique views, using direct intraventricular injection of dilute contrast medium. From the end-diastolic and end-systolic images obtained in each view, analysis of the relative brightness values generated a videodensitometry-based right ventricular ejection fraction for both the right and the left anterior oblique views. These values were compared with those generated by applying the geometry-based Simpson's rule to the orthogonal images. Right ventricular ejection fraction ranged from 22 to 88%. Videodensitometric ejection fraction in the right anterior oblique view correlated well with that in the left anterior oblique view (r = 0.88) and each correlated well with geometry-based ejection fraction (r = 0.91 and 0.82, respectively). In a subset of 18 patients without significant cardiac disease, mean videodensitometric right ventricular ejection fraction was 68% (versus 61% in the abnormal subset), and it correlated closely with left ventricular ejection fraction (r = 0.82). Videodensitometric analysis of digital subtraction images provides a reliable method for calculating right ventricular ejection fraction that is independent of geometry and reliably separates normal from abnormal values. Application of videodensitometric techniques should simplify analysis of the response of the right ventricle to different interventions in patients with cardiac disease.
Adult↗
Quantitative and qualitative effects of intracoronary streptokinase in unstable angina and non-Q wave infarction.
Thrombolytic therapy has been shown to be effective in reopening totally occluded arteries in acute myocardial infarction. Coronary thrombus is also believed to play a role in the pathophysiology of unstable angina and non-Q wave infarction. However, few patients with these two acute coronary syndromes have been treated with intracoronary streptokinase. Therefore, 100,000 to 300,000 IU (mean 177,000 +/- 80,000 IU) of intracoronary streptokinase was infused into 36 consecutive catheterized patients who either presented with an acute episode of unstable angina or had had a recent non-Q wave infarction and in whom a less than 100% occluded ischemia-producing artery could be identified. Qualitative techniques utilizing vessel magnification and quantitative analysis with digital subtraction were performed on the ischemia-producing coronary lesion before and immediately after streptokinase therapy and 3 to 10 days later in 18 patients who were restudied at the time of transluminal coronary angioplasty. Before streptokinase treatment, 24 (67%) of 36 ischemia-producing arteries contained eccentric, irregular lesions. The percent diameter stenosis and percent area stenosis in all ischemia-producing arteries averaged 83.8 +/- 8.3% and 94.8 +/- 3.3%, respectively. After streptokinase treatment there were 23 arteries (64%) with eccentric irregular lesions. The percent diameter stenosis and percent area stenosis in all ischemia-producing arteries were similar to pre-streptokinase values (82.9 +/- 5.9% and 93.8 +/- 4.0%, respectively). At restudy, there were also no significant changes in any quantitative or qualitative variable. Five individual patients showed a significant reduction in percent stenosis after streptokinase. This improvement was independent of duration of symptoms, use of heparin before angiography, streptokinase dose or reduction of fibrinogen levels post-streptokinase. Two additional patients deteriorated clinically and developed total occlusion of the ischemia-producing artery within 12 hours of streptokinase infusion. These data suggest that intracoronary streptokinase may be of limited utility in either unstable angina or recent non-Q wave infarction with a less than 100% occluded ischemia-producing artery. In these syndromes, thrombus may be organized or short infusions may be given too late to be effective. In some cases, thrombus may even be absent. Whether longer infusion of streptokinase or other thrombolytic agents will be of benefit remains to be determined.
Adult↗
Case 5--1987. 45-year-old woman develops acute left ventricular ischemia and dysfunction after subxiphoid drainage of a pericardial tamponade.
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Cardiac Tamponade↗
Chimeric objects and playthings.
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Child↗