Studies in psychoneuroimmunology: psychological, immunological, and neuroendocrinological parameters in Israeli civilians during and after a period of Scud missile attacks.

Twenty-two male volunteers in Jerusalem were subjected to a battery of psychological tests at the height of the Iraqi Scud missile attacks on Israeli cities during the 1991 Persian Gulf War and again after the cessation of hostilities. Venous blood samples were taken at each time point. The separated mononuclear cells and plasma were cryopreserved, and a spectrum of immunological and neuroendocrine assays were performed on the preserved samples.

On microbial states of growth.

It is crucial to the reproducibility of results and their proper interpretation that the conditions under which experiments are carried out be defined with rigour and consistency. In this review we attempt to clarify the differences and interrelationships among steady, balanced and exponential states of culture growth. Basic thermodynamic concepts are used to introduce the idea of steady-state growth in open, biological systems.

Characterization of cell-cycle-specific events in synchronous cultures of Escherichia coli: a theoretical evaluation.

Synchronous growth studies are often used to assess the presence, timing and duration of periodic phenomena in the bacterial cell cycle. In an effort to evaluate the quality and quantity of information on cycle-specific events that can reasonably be expected from such inquiries, a model was constructed of a synchronous culture of Escherichia coli cells as would be derived from a growing population immobilized on a surface, and applied to the case of one stable and one unstable cellular component. The results indicated that, while the presence of cycle-specific events may be easily detectable, their timing and duration are very difficult to establish in synchronous growth experiments.

Nucleoid partitioning and the division plane in Escherichia coli.

Escherichia coli nucleoids were visualized after the DNA of OsO4-fixed but hydrated cells was stained with the fluorochrome DAPI (4',6-diamidino-2-phenylindole dihydrochloride hydrate). In slowly growing cells, the nucleoids are rod shaped and seem to move along the major cell axis, whereas in rapidly growing, wider cells they consist of two- to four-lobed structures that often appear to advance along axes lying perpendicular or oblique to the major axis of the cell. To test the idea that the increase in cell diameter following nutritional shift-up is caused by the increased amount of DNA in the nucleoid, the cells were subjected to DNA synthesis inhibition.

Indigenous free radical scavenger MAK 4 and 5 in angina pectoris. Is it only a placebo?

Thirty patients were evaluated to study the effect of Maharishi Amrit Kalsh (MAK) 4 & 5 on Angina pectoris. The mean angina frequency per month was 8.87.

Dimensional rearrangement of Escherichia coli B/r cells during a nutritional shift-down.

In a search for the mechanism underlying dimensional changes in bacteria, the glucose analogue methyl alpha-D-glucoside was used to effect a rapid reduction in the mass growth rate of Escherichia coli by competitively inhibiting glucose uptake, a so-called nutritional shift-down. The new steady-state cell mass and volume were reached after 1 h, during which the rate of cell division was maintained; rearrangement of the linear dimensions (cell length, diameter), however, required an additional 2 h and caused an undershoot in cell length, consistent with the view that E. coli is slow to modify its diameter.

Control of mini-R1 plasmid replication: a computer simulation.

A molecular model for the control of plasmid R1 replication has been proposed by Nordström, Molin and Light (Plasmid 12, 71-90, 1984), involving three genes: repA, copA, copB. RepA codes for a polypeptide whose synthesis is required for initiation; replication is controlled by regulating this synthesis. CopA encodes a small, unstable, untranslated RNA molecule that inhibits translation of the repA message whereas copB produces a protein that inhibits transcription from the repA promoter.

Partition of plasmid R1: a computer simulation.

A computer-simulated population of individual Escherichia coli cells harboring plasmid R1 parA+/parB- has been used to analyze three possible modes of plasmid segregation: equi-partition, in which plasmids are partitioned equally to daughter cells at cell division; single-site inheritance, in which the products of the most recent replication event are partitioned equally and the remaining plasmids are distributed randomly; and pair-site partition, in which a single, randomly chosen plasmid is actively partitioned to each daughter cell at division and the rest are distributed randomly. Comparison between predicted and experimental plasmid loss-frequency enabled us to rule out the first of these models as a likely mode of action in R1 but was inconclusive regarding the other two. The parA region would therefore seem to partition actively only one pair of plasmids to each daughter cell, the precise selection rule involved remaining unresolved.

Shape changes in Escherichia coli B/r A during agar filtration.

We have investigated the phenomenon of shape distortion in a sample of 1,552 Escherichia coli B/r A cells in balanced exponential growth, during preparation for electron microscopy by agar filtration. Mixed preparations of bacterial cells and polystyrene latex spheres were shadow cast at low angle and the resulting shadows used to obtain quantitative estimates for the dimensions of the dehydrated cells; these then serve as a basis for a model of its shape in three dimensions. A statistical analysis of the projections of clustered cells and the intervening fissures, in nonshadow-cast preparations, provides an estimate of the effects of drying.

Aggregation of Escherichia coli B/r A during agar filtration: effect on morphometric measurements.

We have investigated the phenomenon of particle aggregation in a sample of 71,038 Escherichia coli B/r A cells in balanced exponential growth, during preparation for electron microscopy by agar filtration. The bacteria were photographed in a transmission electron microscope and the dimensions and spatial relationships among all the members of each aggregate were recorded using an interactive image processing system. The proportion of aggregated cells, 22%, is much greater than that found by direct count in a light microscope (7%), implying that most aggregation takes place during the preparation stages.

Relationship between size of parent at cell division and relative size of its progeny in Escherichia coli.

This article examines the empirical basis for the assumption of independence between the relative size (length or surface area) of a newborn cell w and the absolute size of its mother at cell division. Random samples from two strains of Escherichia coli B/r cells in steady-state exponential growth, covering a range of doubling times, were fixed in osmium tetroxide and prepared for electron microscopy by agar filtration. Length and diameter of over 3000 constricted cells were measured from the electron micrographs and cell surface area computed by assuming an idealized geometry of right circular cylinders with hemispherical polar caps.