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Biomedical subjects

L Goldman

Publications and source records attributed to L Goldman.

At least 19 recordsLinked to original sources
PubMed1979

Serial assessment of doxorubicin cardiotoxicity with quantitative radionuclide angiocardiography.

We measured cardiac performance sequentially, using quantitative radionuclide angiocardiography to estimate left ventricular ejection fraction in 55 patients receiving doxorubicin for treatment of cancer. With final doxorubicin dosages greater than 350 mg per square meter, the lowest ejection fraction measured was significantly less than the initial determination. Five patients had severe cardiotoxicity (congestive heart failure). All had an ejection fraction of less than 30 per cent at the time of heart failure, and demonstrated moderate cardiotoxicity (a decline in ejection fraction by at least 15 per cent to a final value of less than 45 per cent) before clinical manifestations. Six patients with moderate toxicity in whom doxorubicin was discontinued did not have heart failure or a further decline in ejection fraction during the follow-up period. Moderate toxicity was continued, but mild toxicity (decline of ejection fraction by greater than 10 per cent, noted in 11 patients) was not well predicted. The assessment of radionuclide left ventricular ejection fraction during doxorubicin therapy may make it possible to avoid congestive heart failure.

Adult↗
PubMed1979

Multiple gated cardiac blood pool imaging for left ventricular ejection fraction: validation of the technique and assessment of variability.

The intrinsic variability and accuracy of left ventricular ejection fraction determined by multiple gated cardiac blood pool imaging was evaluated in 83 patients. Ejection fraction by gated studies correlated well with data from first pass radionuclide angiocardiography (r = 0.94) and from contrast angiography (r = 0.84). Intra- and interobserver variabilities of absolute ejection fraction were minimal (mean +/- standard deviation 1.4 +/- 1.2 and 1.6 +/- 1.5 percent, respectively) and were not different for normal (ejection fraction 55 percent or greater) and abnormal patients. Ejection fraction was determined twice in 70 patients: on the same day at intervals separated by 1 to 2 hours (41 patients) and on 2 different days (29 patients). Ejection fraction ranged from 18 to 91 percent and was normal in 37 patients. There was no difference in mean serial variabilities of absolute ejection fraction for all repeat studies performed on the same and separate days (3.3 +/- 3.1 versus 4.3 +/- 3.1 percent (not significantly different). The mean variability of absolute ejection fraction for repeat studies in normal patients was significantly greater than in abnormal patients (5.4 +/- 4.4 versus 2.1 +/- 2.0 percent, P less than 0.01). The incidence rate of absolute interstudy changes of 5 percent or more was significantly higher in normal than in abnormal patients (P less than 0.01). This differential variability should be considered in interpreting sequential changes in left ventricular ejection fraction. To be attributed to nonrandom physiologic alterations, the absolute change in ejection fraction should be 10 percent or more in normal patients and 5 percent or more in abnormal patients.

Angiocardiography↗
PubMed1979

Internally perfused Myxicola giant axons showing long-term survival.

An improved method for internally perfusing the Myxicola giant axon based on removing the axoplasm by dispersing it in KCl-KF salt solutions is described. Proteolytic enzymes are not introduced. With this improved method perfused preparations show long-term stability of their electrical properties and the ability to generate action potentials for many hours. Mean initial values for resting membrane potential, action potential amplitude, and peak inward current were -68 mV, 118 mV, and 3.62 mA/cm2, respectively. Mean resting membrane resistance was 75% of that in intact axons. In one series of voltage clamp experiments, perfused preparations remained excitable for a mean period of 5 1/2 h, but this period could exceed 10 h. 4 min are needed for exchange of internal solutions. At least 50 mM KF is required both in the axoplasm liquefying solution and in the standard perfusate to obtain stable preparations.

Action Potentials↗
PubMed1979

Surgery by laser for malignant melanoma.

Lasers have been used for photocoagulation and photoexcision of malignant melanomas when conventional instruments could not be used. Lasers are useful for destruction of cutaneous metastases from malignant melanomas especially when numerous and dispersed. The color of melanomas makes for selective absorption of energy from lasers in the visible light range. Surgery by lasers is still an investigative form of surgery with current research studies on immediate placement of grafts, lymphatic migration of malignant cells after laser surgery, and relevant immunologic studies.

Humans↗
PubMed1979

Anticoagulants and myocardial infarction. The problems of pooling, drowning, and floating.

The time and expense required for adequate-sized, randomized control trials may often tempt investigators to try to answer long-standing clinical questions by retrospective analysis of data combined from old studies. In a recent example of such "pooling," the authors concluded not only that anticoagulation is beneficial in acute myocardial infarction but also that further experimental trials would be unethical. This conclusion can be disputed because of scientific, statistical, and clinical standards that were not fulfilled in the "pooled" analysis. Scientifically, the pooling of data from different sources can be valid only if the component studies contain patients who are sufficiently similar in diagnosis, clinical severity, principal treatment, and outcome events. Mathematically, exact numbers rather than percentages should be pooled. Clinically, even when the pooling process is appropriate, recent changes in ancillary therapy may negate the applicability of the old data to current medical practice.

Anticoagulants↗
PubMed1979

The challenge of biophysics to dynamic dermatology.

Dermatologic biophysics has much to offer both clinical and investigative dermatology. For the clinician, the radiation biophysicist can provide accurate measurements of ionizing and nonionizing outputs, including those for PUVA, and critical evaluation of radiation safety measures. In optics, there is a need for accurate measurements of skin color and examination of the skin at moderate magnification. The biophysicist, with the biomedical engineer, can improve all the physical modality instrumentation used in practice. In investigative dermatology, there is the cellular biophysics of radiation. Doppler techniques for skin circulation, spectroscopy of living cells, and many other applications are suggested for current and future studies.

Biophysical Phenomena↗
PubMed1979

Laser surgery for blue rubber bleb nevus.

A 21-year-old man has had extensive cutaneous and visceral manifestations of the blue rubber bleb nevus syndrome since birth. Surgical therapy with the carbon dioxide laser was successful in removing 225 skin hemangiomas without recurrences or complications such as hemorrhage and infection. The cosmetic and follow-up results have been excellent.

Adult↗
PubMed1978

Initial conditions and the kinetics of the sodium conductance in Myxicola giant axons. I. effects on the time-course of the sodium conductance.

The effects of conditioning polarizations, ranging from--150 to 0 mV and of durations from 50 mus to 30 ms, on the time-course of GNa during test steps in potential were studied in Myxicola giant axons. Beyond the effects of conditioning polarizations on the amplitude of GNa, the only effect was to produce a translation of GNa(t) along the time axis without a change in shape. For depolarizing conditioning potentials, Hodgkin-Huxley kinetics predict time shifts about threefold greater than found experimentally, whereas the predictions of the coupled model of Goldman (1975. Biophys. J. 15:119--136) were in approximate agreement with our experiments. The time shifts developed over an exponential time-course as the conditioning pulse duration was increased. The time constant of development of the time shift was considerably faster than, and showed the opposite dependency on potential from, the values predicted by both models. It had a mean Q10 of 1/2.50. This fast activation process cannot account for the observed rise time behavior of GNa, suggesting that there is an additional activation process. All results are consistent with the idea that the gating structure displays more than three states, with state intermediate between rest and conducting.

Animals↗
PubMed1978

Initial conditions and the kinetics of the sodium conductance in Myxicola giant axons. II. Relaxation experiments.

The time-course of the decay of INa on resetting the membrane potential to various levels after test steps in potential was studied. The effects of different initial conditions on these Na tail currents were also studied. For postpulse potentials at or negative to -35 mV, these currents may be attributed nearly entirely to the shutdown of the activation process, inactivation being little involved. Several relaxations may be detected in the tail currents. The slower two are well defined exponentials with time constants of approximately 1 ms and 100 mus in the hyperpolarizing potential range. The fastest relaxation is only poorly resolved. Different initial conditions could alter the relative weighting factors on the various exponential terms, but did not affect any of the individual time constants. The activation of the sodium conductance cannot be attributed to any number of independent and identical two-state subunits with first order transitions. The results of this and the previous paper are discussed in terms of the minimum kinetic scheme consistent with the data. Evidence is also presented suggesting that there may exist a small subpopulation of channels with different kinetics and a faster rate of recovery from TTX block than the rest of the population.

Animals↗