Scott P. Layne

Factors underlying spontaneous inactivation and susceptibility to neutralization of human immunodeficiency virus

To determine the factors governing inactivation and neutralization, physical, chemical, and biological assays were performed on a molecular clone of human immunodeficiency type 1 (HIV-1HXB3). This included quantitative electron microscopy, gp120 and p24 enzyme-linked immunosorbent assays, reverse, transcriptase assays, and quantitative infectivity assays. For freshly harvested stocks, the ratio of infectious to noninfectious viral particles ranged from 10(-4) to 10(-7) in viral stocks containing 10(9) to 10(10) physical particles per milliliter. There were relatively few gp120 knobs per HIV particle, mean approximately 10 when averaged over the total particle count. Each HIV particle contained a mean approximately 5 x 10(-17) g of p24 and approximately 2 x 10(-16) g of RNA polymerase, corresponding to about 1200 and 80 molecules, respectively. The spontaneous shedding of gp120 envelope proteins from virions was exponential, with a half-life approximately 30 hr. The loss of RNA polymerase activity in virons was also exponential, with a half-life approximately 40 hr. The physical breakup of virions and the dissolution of p24 core proteins were slow (half-life greater than 100 hr) compared to the gp120 shedding and polymerase loss rates. The decay of HIV-1 infectivity was found to obey superimposed single- and multihit kinetics. At short preincubation times, the loss of infectivity correlated with spontaneous shedding of gp120 from virions. At longer times, an accelerating decay rate indicated that HIV requires a minimal number of gp120 molecules for efficient infection of CD4+ cells. The blocking activity of recombinant soluble CD4 (sCD4) and phosphonoformate (foscarnet) varied with the number of gp120 molecules and number of active RNA polymerase molecules per virion, respectively. These results demonstrate that the physical state of virions greatly influences infectivity and neutralization. The knowledge gained from these findings will improve the reliability of in vitro assays, enhance the study of wild-type strains, and facilitate the evaluation of potential HIV therapeutics and vaccines.

Dimensionality of the Human Electroencephalogram

The goal was to evaluate anesthetic depth in patients by dimensional analysis. Although it was difficult to obtain clean EEG records from the operating room due to noise of electrocautery and movement of the patients head by operating room personnel. The results are presented on one case of our calculations, followed by a discussion of problems associated with dimensional analysis of the EEG. We consider only two states: aware but quiet, and medium anesthesia. The EEG data we use comes from Hanley and Walts. It was selected because anesthesia was induced by a single agent, and because of its uninterrupted length and lack of artifacts. 26 refs., 27 figs., 1 tab.

Raman Spectroscopy of Bacillus megaterium Using an Optical Multi-channel Analyzer

Using a spectrometer equipped with an optical multi-channel analyzer as the detector, we have observed the Stokes laser-Raman spectra of metabolically active B. megaterium from 930-1720 cm-1. No Raman lines attributable to the metabolic process nor the cells themselves were found. This result is consistent with our previous laser-Raman measurements of synchronous E. coli cultures.

The Modification of Davydov Solitons by the Extrinsic H-N-C=O Group

The molecular mechanisms which underlie general anesthesia are not clearly understood. First, there are two chemically disparate classes of pharmacologic agents to consider (both intravenous and volatile) which induce general anesthesia. Second, investigators in the field are divided into two differing camps of thought: (1) those who believe that anesthetics work by altering normal membrane fluidity, and (2) those who believe that anesthetics work by perturbing normal protein function. Recently, there is growing evidence that the “perturbed protein” hypothesis holds greater promise over the “altered fluidity” hypothesis in explaining the molecular mechanisms of general anesthesia.1The simplest working idea is that general anesthetics act by binding directly to a particularly sensitive protein, which may or may not be located in a lipid membrane, and inhibiting its normal function.

Experiments for the Detection of Solitons in Biopolymers

Unfortunately it is not possible to sneak inside a biological system with a camera and snap a picture of an object labeled “soliton”. And yet that is not unlike what we are trying to do when we ask solitons in biological systems to reveal themselves to experimental scrutiny. The sign must say “soliton” and not “exciton” or “conformational change” or any other plausible identification, because the theory of nonlinear interactions is relatively new to biophysics and it has not yet been firmly established experimentally. Moreover, such confirmation is not likely to come from any single definitive experiment. Rather, we expect to build up a large body of evidence, from a variety of experiments that approach the problem from different angles, which when taken all together would constitute a convincing case.