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Biomedical subjects

L Feldman

Publications and source records attributed to L Feldman.

At least 109 records · Page 6Linked to original sources
PubMed1984

Local thrombolysis in the treatment of arterial graft occlusions.

Nineteen patients with 20 occluded arterial bypass grafts were treated with local infusion of streptokinase. Grafts treated included four aortofemoral graft limbs, 14 femoropopliteal or femorotibial grafts, one axillofemoral graft, and one transpubic femorofemoral graft. Complete lysis of thrombus was possible in 12 patients, partial lysis in five patients, and no lysis in two patients. Thrombolytic therapy was thought to be beneficial in the management of 14 patients. In two of these 14 only thrombolysis was required to restore and maintain graft patency, and in an additional two patients angioplasty was performed after thrombolytic therapy with no subsequent therapy necessary. In three patients who were initially poor operative risks, surgery could be postponed. Thrombolysis revealed the probable cause of thrombosis in 12 patients. Complications included four bleeding episodes, two of which were significant. There were no significant embolic complications. Unsuccessful thrombolytic therapy did not result in worsening of ischemia in any patient. Local infusion of thrombolytic agents is a useful adjunct in the management of occluded bypass grafts.

Adult↗
PubMed1983

Two sensitive echocardiographic techniques for detecting doxorubicin toxicity.

This investigation was designed to evaluate echoes of patients who received a course of doxorubicin (225-550 mg/m2) by two sensitive indicators of myocardial fibrosis: (1) M-mode scans of thickening-thinning curves of the left ventricular posterior wall (LVPW), and (2) two-dimensional qualitative evaluation of LVPW contraction at three levels of the LV short axis (leaflet, chordal, and papillary). These were compared to standard M-mode shortening fraction (delta S). Eighteen children with cancer were evaluated; 11 had received doxorubicin and 7 were treated with other agents. Echocardiographers were unaware of the treatment category. All controls and 10 of 11 doxorubicin patients had normal delta S. An M-mode echocardiogram of the expanded LVPW was digitized and wall thickness was evaluated by determining if diastolic relaxation had the normal two phases or only one; six of ten doxorubicin patients and no controls had abnormal relaxation. Qualitative evaluation of LVPW and septal contraction toward the center of the ventricle showed that seven of eleven patients who received doxorubicin and one control (a postthoracotomy patient) had contraction deficits. Six of seven with contraction deficit were the same patients with slowed relaxation. The greatest contraction deficit occurred in the LVPW behind the posterior mitral leaflet. Patients with more extensive involvement had an additional contraction deficit extending to the apex. These tests are more sensitive for detection of doxorubicin toxicity than delta S.

Adolescent↗
PubMed1983

Characterization of the immediate-early functions of pseudorabies virus.

The immediate-early transcripts of pseudorabies virus have been located in a region of the genome situated internally within the inverted repeat between map positions 0.99 and 0.95. A single immediate-early transcript (approximately 6 kb) can be detected both in the cytoplasmic and nuclear fractions of infected, cycloheximide-treated cells. Analysis of the proteins synthesized after removal of cycloheximide from infected cells or after translation in vitro of the RNA isolated from these cells revealed the presence of a single protein (180K) not present in similarly treated, uninfected cells. That this is a virus protein and is specified by the immediate-early region of the genome was shown by selection and translation of mRNA hybridizing with virus DNA from the appropriate region of the genome. The effects of infection of cells with a temperature-sensitive mutant (tsG1) defective in the 180K protein were studied. At the nonpermissive temperature only immediate-early RNA was transcribed and only one virus protein, the 180K protein was synthesized. Inhibition of cellular protein and DNA synthesis was also observed. After shift down of tsG1-infected cells from the nonpermissive to the permissive temperature at 3 hr post infection, a transition to early RNA transcription occurred. However, if the shift down was delayed until 5 hr post infection, transcription of the virus genome was completely inhibited and an abortive infection ensued. Shift of the mutant-infected cells from the permissive to the nonpermissive temperature resulted in a decrease in the rate of accumulation of early and late transcripts, and a resumption of the synthesis of immediate-early RNA and protein. From these as well as from previous results, it is concluded that pseudorabies virus codes for a single multifunctional immediate-early protein which is essential for the transcription of immediate-early to early RNA and is required for the continuous transcription of early (and late) RNA. The immediate-early protein is also self-regulatory; the presence of the functional immediate-early protein represses the transcription of its RNA. In addition, the immediate-early protein of pseudorabies virus appears to play a direct role, under certain conditions, in the inhibition of cellular macromolecular synthesis.

Chromosome Mapping↗
PubMed1983

Serial left ventricular wall measurements in Duchenne's muscular dystrophy.

In 19 patients with Duchenne's muscular dystrophy, left ventricular wall thickness in end-systole and end-diastole was determined serially every 12 months by echocardiography and compared with ventricular wall growth in normal subjects. In the normal subjects, left ventricular wall thickness increased linearly with increasing body surface area. A control group of wheelchair-bound patients with a variety of neurologic disorders, although not followed serially, had a distribution of end-diastolic wall thickness values similar to that of the normal subjects. In patients with muscular dystrophy, wall thickness increased linearly with respect to body surface area for some time and then began to thin. The time at which thinning began was not directly related to age, although it was more common in older than in younger patients. Those patients who died demonstrated marked deviation from normal wall growth. Free wall thinning is probably a result of fibrosis and loss of myofibrils.

Adolescent↗
PubMed1983

Development and evaluation of pulsatile roller pump and tubing for cardiac assistance.

In our laboratories we have developed a roller pump for cardiopulmonary bypass and circulatory assistance that has the ability to produce steady or pulsatile flow. The pulsatile mode can also be used for counterpulsation. The roller pump has been tested both experimentally and clinically. Studies have also been performed in vitro and in vivo to evaluate and select the best medical-grade roller pump tubing to be used in the pump for short- and long-term support. In vitro tests included rebounding of tubing volume versus revolutions per minute, rebounding over time with continuous pumping, flex life, and spallation. In vivo testing was performed in mongrel dogs using heparinless left heart bypass pumping for 6 h. Hematologic studies were performed during the procedure. Postmortem examination was performed, looking especially for thromboembolism. The tubing and connectors were also inspected. The results of the in vivo and in vitro tests of all tubings were then compared.

Animals↗
PubMed1983

Transcatheter vessel occlusion: angiographic results versus clinical success.

A review was made of 219 transcatheter vessel occlusion procedures performed over a ten-year period for control of hemorrhage, tumor palliation, or blood supply redistribution prior to intra-arterial chemotherapy. Complete angiographic success was obtained in 85% of the procedures, with partial success in 8%; complete clinical success was achieved in 53% of patients, with partial success in 23%. The most satisfactory clinical results were obtained with hemorrhagic gastritis and pelvic trauma. Embolizations for duodenal ulcer hemorrhage and transhepatic variceal occlusion were the least clinically successful, although isobutyl-cyanoacrylate appeared to be a significant improvement in angiographic therapy for duodenal ulcer. The overall complication rate was 13%, with one third of the complications clinically silent. These results indicate that transcatheter vessel occlusion is a relatively safe and effective method for control of hemorrhage or tumor infarction.

Abdomen↗
PubMed1982

N abundance of nodules as an indicator of N metabolism in n(2)-fixing plants.

This paper expands upon previous reports of (15)N elevation in nodules (compared to other tissues) of N(2)-fixing plants. N(2)-Fixing nodules of Glycine max (soybeans), Vigna unguiculata (cowpea), Phaseolus vulgaris (common bean), Phaseolus coccineus (scarlet runner bean), Prosopis glandulosa (mesquite), and Olneya tesota (desert ironwood) were enriched in (15)N. Nodules of Vicia faba (fava beans), Arachis hypogaea (peanut), Trifolium pratense (red clover), Pisum sativum (pea), Lathyrus sativus (grass pea), Medicago sativa (alfalfa), and Lupinus mutabilis (South American lupine) were not; nor were the nodules of nine species of N(2)-fixing nonlegumes. The nitrogen of ineffective nodules of soybeans and cowpeas was not enriched in (15)N. Thus, (15)N elevation in nodules of these plants depends on active N(2)-fixation. Results obtained so far on the generality of (15)N enrichment in N(2)-fixing nodules suggest that only the nodules of plants which actively fix N(2) and which transport allantoin or allantoic acid exhibit (15)N enrichment.

Journal Article↗
PubMed1982

Serial two-dimensional echocardiography in Duchenne muscular dystrophy.

Patients with Duchenne muscular dystrophy (DMD) are known to have progressive epicardial fibrosis of the free wall of the left ventricle, but standard noninvasive M-mode echocardiographic tests of left ventricular function are relatively insensitive detectors of this cardiomyopathy. We therefore used two-dimensional echocardiography to record three short axis levels of the left ventricle in 13 Duchenne patients. Serial studies were separated by 2 years for most patients. The two-dimensional echocardiographic technique allows qualitative evaluation of segmental contraction of the left ventricle. Four general principles were found during this study: (1) Obvious contraction abnormalities of the left ventricle were present in most patients with DMD. (2) In most patients, the contraction deficit was first noted in the left ventricular posterior free wall behind the mitral valve. (3) Once a contraction deficit was observed, the area of abnormal contraction progressed inferiorly to include additional areas of the left ventricular posterior free wall. (4) Standard M-mode left ventricular function techniques were unreliable for detecting individuals with segmental contraction abnormalities.

Adolescent↗
PubMed1981

Range gated Doppler ultrasound detection of contrast echographic microbubbles for cardiac and great vessel blood flow patterns.

Ultrasonic contrast techniques allow tracking of blood flow in patients with cardiac malformations. One problem often encountered in M-mode contrast is inability to generate adequate microbubbles for recording. Theoretically, echo Doppler should be more sensitive for detection of microbubbles. To test this hypothesis, results of 75 saline injections were studied at catheterization in 16 patients by simultaneously recording contrast M-mode and echo Doppler studies. For this part of the investigation, an ATL 500 system was utilized. The M-mode of this system was found to provide identical information to that of SmithKline. Records were evaluated without identification of the patient. In all instances (n = 20) in which microbubbles were not expected on the basis of flow patterns, none were detected by Doppler. One error occurred for M-mode. Contrast in the direction of flow was visualized in 50 of 55 injections by echo Doppler. In these, a frequency dispersion was present, but even more striking was a marked rise in the time interval histographic input signal strength indicator. Only 40 of 55 simultaneous M-mode echoes showed a contrast effect (p less than 0.05). Doppler microbubble detection was usually represented by a much stronger signal than was M-mode contrast. This investigation demonstrates that range gated Doppler is an effective method for microbubble detection.

Child↗
PubMed1981

Isolation and characterization of a temperature-sensitive uncoating mutant of pseudorabies virus.

During the course of characterizing a series of temperature-sensitive mutants of pseudorabies virus, we found one (designated tsL) that did not produce cytopathic changes in rabbit kidney cells at the non-permissive temperature (41 degree C). Although the mutant adsorbed to and penetrated the cells in a normal fashion, virus RNA was not synthesized at 41 degree C in the infected cells. However, if the cells were first incubated at the permissive temperature (32 degree C), virus RNA synthesis occurred at the non-permissive temperature. This occurred even if, during the incubation period at 32 degree C, the expression of viral functions was prevented by treatment with an inhibitor of protein synthesis. The DNA in tsL virions did not appear in the cell nucleus at 41 degree C, and full, non-enveloped nucleocapsids could be recovered from the cytoplasm of tsL virus-infected cells. These results show that the nucleocapsids of tsL remain intact at the non-permissive temperature and that tsL is an uncoating mutant.

Adsorption↗
PubMed1980

Frequency entrainment of squid axon membrane.

Sinusoidally varying stimulating currents were applied to space-clamped squid giant axon membranes in a double sucrose gap apparatus. Stimulus parameters varied were peak-to-peak current amplitude, frequency, and DC offset bias. In response to these stimuli, the membranes produced action potentials in varying patterns, according to variation of input stimulus parameters. For some stimulus parameters the output patterns were stable and obviously periodic with the periods being simple multiples of the input period; for other stimulus parameters no obvious periodicity was manifest in the output. The experimental results were compared with simulations using a computer model which was modified in several ways from the Hodgkin-Huxley model to make it more representative of our preparation. The model takes into account K+ accumulation in the periaxonal space, features of Na+ inactivation which are anomalous to the Hodgkin-Huxley model, sucrose gap hyperpolarization current, and membrane current noise. Many aspects of the experiments are successfully simulated but some are not, possibly because some very slow process present in the preparation is not included in the model.

Action Potentials↗
PubMed1980

Conformational changes in the H3 . H4 histone complex. Serological and circular dichroism studies.

The H3.H4 complex has been extracted from calf thymus chromatin in either 0.05 M NaOAc, pH 5.0, or in 2.0 M KCl, 0.1 M KPO4, pH 6.7, and both forms have been shown to consist solely of histones H3 and H4 when examined on sodium dodecyl sulfate-polyacrylamide gels. Serological and circular dichroism analyses indicate the existence of structural differences between the two forms. Dilution of the high salt form of the complex into low salt produces a time-dependent conformational change which is related to reduction in the alpha helix content of the complex and which exposes antigenic sites on the complex. The existence of multiple forms of the H3.H4 complex may be related to the dynamic equilibrium of nucleosome structure in vivo.

Animals↗
PubMed1980

[Metrizamide radiculography with simplified dynamic test (author's transl)].

The development of metrizamide, a recent hydrosoluble contrast medium, has opened up the possibility of dynamic lumbosacral radicolugraphy, but in the opinion of the authors only the upright position is adequate to accentuate or reveal new pathological appearances. This was the case in 68 out of 100 consecutive radiculographies performed.

Back Pain↗