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Biomedical subjects

L Goldman

Publications and source records attributed to L Goldman.

At least 433 records · Page 24Linked to original sources
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↗
PubMed1978

Cardiac risk factors and complications in non-cardiac surgery.

In an attempt to assess cardiac risk in non-cardiac surgery, 1001 patients over 40 years of age who underwent major operative procedures were examined preoperatively, observed through surgery, studied with at least one postoperative electrocardiogram, and followed until hospital discharge or death. Documented postoperative myocardial infarction occurred in only 18 patients; though most of these patients had some pre-existing heart disease, there were few preoperative factors which were statistically correlated with postoperative infarction. Postoperative pulmonary edema was strongly correlated with preoperative heart failure, but 21 of the 36 patients who developed pulmonary edema did not have any prior history of heart failure. Nearly all of these 21 patients were elderly, had abnormal preoperative electrocardiograms, and had intraabdominal or intrathoracic surgery. In the absence of an acute infarction, bifascicular conduction defects, with or without PR interval prolongation, never progressed to complete heart block. Spinal anesthesia protected against postoperative heart failure but not against other cardiac complication. By multivariate regression analysis, postoperative cardiac death was significantly correlated with (a) myocardial infarction in the previous 6 months; (b) third heart sound or jugular venous distention immediately preoperatively; (c) more than five premature ventricular contractions per minute documented at any time preoperatively; (d) rhythm other than sinus, or premature atrial contractions on preoperative electrocardiogram; (e) age over 70 years; (f) significant valvular aortic stenosis; (g) emergency operation; (h) a 33% or greater fall in systolic blood pressure for more than 10 minutes intraoperatively. Notably unimportant factors included smoking, glucose intolerance, hyperlipidemia, hypertension, peripheral atherosclerotic vascular disease, angina, and distant myocardial infarction.

Adult↗
PubMed1978

Supraventricular tachyarrhythmias in hospitalized adults after surgery. Clinical correlates in patients over 40 years of age after major noncardiac surgery.

To assess the clinical correlates and therapeutic outcome of new postoperative supraventricular tachyarrhythmias, 916 patients who were in sinus rhythm throughout the course of surgery were prospectively followed after major noncardiac surgery. The 35 patients (4 percent) who developed new postoperative supraventricular tachyarrhythmias frequently had concurrent medical problems, such as the following: other acute cardiac conditions, 16 patients (46 percent); major infections, 11 patients (31 percent); preexisting hypotension, ten patients (29 percent); anemia, nine patients (26 percent); metabolic derangements, eight patients (23 percent); parenteral therapy with new medications, eight patients (23 percent); and hypoxia, seven patients (20 percent). The arrhythmias of all treated patients reverted to sinus rhythm; 40 percent (14 patients) required no new therapy with cardiac medications, and only two patients required electrical cardioversion. No deaths were related to the supraventricular tachyarrhythmias, but 49 percent (17) of the patients died from their concurrent medical problems. The onset of a new postoperative supraventricular tachyarrhythmia should prompt a search for remediable medical problems. Direct antiarrhythmic therapy is often unnecessary and is usually secondary in importance to correction of the causes of the arrhythmia.

Adult↗
PubMed1977

Multifactorial index of cardiac risk in noncardiac surgical procedures.

To determine which preoperative factors might affect the development of cardiac complications after major noncardiac operations, we prospectively studied 1001 patients over 40 years of age. By multivariate discriminant analysis, we identified nine independent significant correlates of life-threatening and fatal cardiac complications: preoperative third heart sound or jugular venous distention; myocardial infarction in the preceding six months; more than five premature ventricular contractions per minute documented at any time before operation; rhythm other than sinus or presence of premature atrial contractions on preoperative electrocardiogram; age over 70 years; intraperitoneal, intrathoracic or aortic operation; emergency operation; important valvular aortic stenosis; and poor general medical condition. Patients could be separated into four classes of significantly different risk. Ten of the 19 postoperative cardiac fatalities occurred in the 18 patients at highest risk. If validated by prospective application, the multifactorial index may allow preoperative estimation of cardiac risk independent of direct surgical risk.

Age Factors↗
PubMed1977

Laser surgery of a digital angiosarcoma: report of a case and six-year follow-up study.

A single digital angiosarcoma was excised by a carbon dioxide laser with small portions of this tumor excised by the scalpel and the high-frequency electrosurgical knife. The patient has been followed for 6 years without any local recurrence or additional lesions. There is a brief summary of investigative studies with lasers in benign and malignant vascular tumors.

Carbon Dioxide↗
PubMed1977

Digital mucinous pseudocysts.

Thirty-one patients with 46 digital mucinous pseudocysts are reviewed. The pseudocysts are usually soft, fluctuant, dome-shaped, dimpled, smooth lesions located near and often associated with a linear defect of the fingernail. Transillumination confirms the diagnosis. Treatment is conservative, usually consisting of intralesional injections. If surgery is necessary, distal interphalangeal joint injection of methylene blue aids in complete removal by identifying the mesothelial-lined pedicle leading from the distal joint to the pseudocyst.

Adult↗
PubMed1977

Automatic processing quality assurance program: impact on a radiology department.

A method for evaluating processing variability as well as quantitative data on a quality assurance program tested at a radiology department are presented. Thirty per cent of all retakes due to improper overall density could be attributed to processing variation; these could be prevented through a QA program which is highly cost-effective in both monetary and patient-care terms.

Cost-Benefit Analysis↗