Calculation of protoplast freezing strain in multicellular plant tissues

A method for calculating the contraction strain (or the converse stress) to protoplasts of frozen multicellular plant tissues is described. The method requires (i) a nuclear magnetic resonance (NMR) measure of the quantity of bound water per gram dry weight (K), (ii) a gravimetric measure of grams of H₂O per gram dry weight (L₀), (iii) a measure of solute concentration in non-frozen cells (C₀), (iv) an estimate of the specific volume of tissue dry matter (0.625 ml/g), (v) an NMR measure of the fraction of tissue water that is intracellular osmotic water (P_a), and (vi) a measure of the fraction of the dry weight that is cell wall (f_cw). This method is a refinement of previous methods that calculate cell contraction strain from four (L₀, K, C₀, and 0.625) of the above six measurements. Comparison of the calculated protoplast strain to the calculated cell strain indicates that the two measures are quite similar, however, the measure of protoplast strain is, in theory, a more appropriate measure of the freezing strain. It is also demonstrated that derivation of a measure of strain from the parameters controlling it is useful, because it allows one to evaluate the relative contribution of each parameter in preventing the development of strain.     

Genital herpes and personality

Genital herpes, while having gained considerable attention as an important psychosexual disease, is not well understood. Precisely what factors trigger infectious reactivation is an important question that has yet to be answered. The present study investigated the relationship between recurrent genital herpes and personality. High and low recurrers were administered a demographic and disease history questionnaire and the Minnesota Multiphasic Personality Inventory (MMPI). Results revealed that, compared to low recurrers, the mean MMPI profile of high recurrers showed significantly greater elevations on nine of ten scales. The degree and pattern of elevation in the high profile is consistent with increased levels of autonomic arousal and stress. These findings are interpreted as suggestive of the possible role of personality in influencing the rate of infectious recurrence in genital herpes sufferers. The implications for psychologically based treatment strategies are discussed.     

Bone remodeling rates and skeletal maturation in three archaeoloqical skeletal populations

Cortical bone remodeling rates for rib samples from three archaeological populations and a modern autopsy sample were determined using an algorithm developed by Frost. (Frost [1987a] Calcif. Tissue Res. 3:211–237). When plotted against the relative antiquities for population samples, histomorphometric variables; i.e., activation frequency (μ _rc, net bone formation (_netV_f,r,t), and mean annual bone formation rate (V_f,r,t), exhibit a concordant trend of increased cortical bone remodeling activity levels over time. Two intensive foraging populations, Windover and Gibson, are similar for all bone remodeling parameters and have the lowest remodeling activity levels among the samples. The more recent Ledders sample, which is reported to practice agricultural subsistence, is consistently intermediate between these and a modern autopsy sample. Although there appear to be differences in bone formation rates among the populations, it is concluded that these differences cannot be attributed to differences in bone remodeling rates among the populations, but rather are reflecting different effective ages of adult compacta for their ribs. These findings suggest that the earlier populations, particularly Windsor and Gibson, appear to have reached skeletal maturity at an older age than observed for modern. © 1995 Wiley-Liss, Inc.     

Replication of parvoviral DNA. I. Characterization of a nuclear lysate system.

We have developed a nuclear lysate system from infected, synchronized cells capable of synthesizing unit-length parvoviral DNA in vitro. It was necessary to supplement the nuclear lysates with the polyamines, spermidine and spermine, to prevent degradation of template and product DNAs. In this system RF, RI, and single-stranded progeny DNAs were synthesized. Label incorporated in viral RF DNA in vivo appeared first in RI DNA and then in single-stranded DNA during incubation in vitro. By sedimentation the product DNAs were identical to those found in infected cells. Their viral identity was confirmed by hybridization. The addition of ribonucleotides, RNase, or alpha-amanitin did not affect parvoviral DNA synthesis in this system. The results with the specific inhibitors of mammalian DNA polymerases, aphidicolin, N-ethylmaleimide, and 2',3'-dideoxythymidine 5'-triphosphate indicated that DNA polymerase alpha was required for synthesis of parvoviral DNA in the nuclear lysates. This requirement was confirmed by experiments with antibody to bovine DNA polymerase alpha.     

Role of Colanic Acid Polysaccharide in Serum Resistance In Vivo and in Adherence

The production of an extracellular layer of polysaccharide, termed the capsule, is a common feature of many bacteria. Capsules play a vital role in permitting evasion of the host immune specific and nonspecific defenses as well as helping in adhesion for colonization of host tissue. Colanic acid capsule is usually produced in low quantities and is a common feature of several enteric bacteria. The role of the colanic acid capsule in aiding adhesion and virulence was investigated. Encapsulated and unencapsulated cells were injected into granuloma pouches that were formed on the backs of rats. During the first 50 h, the viability of the matched encapsulated and unencapsulated cells decreased. These studies showed that colanic acid capsule does not confer resistance to the bactericidal activity of serum or to phagocytosis in vivo, since there was no significant difference in the survival rates of both strains over time. Adherence studies were conducted in monolayers of human carcinoma intestinal cells (T84) with the same matched strains. After incubating radioactively labeled bacteria with the colon cells, the level of adherence was determined by measuring the radioactivity remaining in the tissue culture wells. The results of these experiments indicated that the unencapsulated cells adhered more readily to the intestinal cells, suggesting that colanic acid capsule interferes with adherence in this model system. Received: 7 June 1996 / Accepted: 10 July 1996     

Compensatory partitioning of carbon budgets by the grass shrimp (Palaemonetes pugio) and implications for predator prey relationships

Carbon utilization and allocation were examined between two populations of shrimp (Palaemonetes pugio) to determine the possible effects of living in an area of high anthropogenic impact. Carbon assimilation has been studied in P. pugio, but no study has looked at how assimilation might be influenced by contaminants. Anthropogenic effects on carbon assimilation in grass shrimp represent a major unmeasured impact on the carbon budget of multi-cellular organisms in estuaries and near shore environments. The influence of anthropogenic contamination on carbon assimilation has implications for predicting the environmental impact of contaminants, for models of estuarine function, and trophic transfer from the dominant macroscopic detritus processor to species of direct economic importance. Shrimp budgets were compared between two populations, one from a highly polluted marsh creek system in Northern New Jersey, and one from a clean reference site in Southern New Jersey. All components of the carbon budgets were measured directly including carbon allocated to reproduction. Carbon lost to respiration was lower in shrimp from the polluted system allowing them to have increased reproductive output. This is examined in the context of previous studies that show lowered predation by a piscine predator at the polluted site, resulting in a trophic cascade and changes in ecosystem function due to anthropogenic impacts.     

Long-term preservation of canine bone marrow: in vitro studies.

In vitro studies were performed on canine bone marrow frozen with DMSO and stored in liquid nitrogen for 2 to 6 months. The results are compared with previously reported parallel in vivo experiments that demonstrated no loss of stem cells. When studies were performed immediately after thawing, there was no substantial drop in the count of nucleated cells and, except for megakaryocytes, there was no alteration of the bone marrow morphology. After two washes, and removal of DMSO, the nucleated cell count dropped to 50% of its previous value. Optic and electron microscopy showed severe damage in mature myeloid elements. In some instances, the cells had a condensed nucleus similar to the red-purple inclusion body of LE cells (as observed in systemic lupus erythematosus), and electron microscopy showed heavy chromatin clumping. On the other hand, both optic and electron microscopy showed a good preservation of lymphocytes, plasmocytes, and erythroid precursors. Two-hour DNA synthesis slightly dropped after storage, and this drop appeared more consistent when related to a constant volume of bone marrow (50 microliters) rather than to a constant number of nucleated cells (10(6)). In five instances frozen and thawed bone marrow was grown in short-term cultures, and analysis of 98 metaphases showed no major aberrations of the chromosomes and only 2% of minor aberrations, such as breakages and fragments. These data, compared with the results of previous in vivo experiments that showed no loss of stem cells after 5 months storage, suggest that stem cells are less sensitive to freezing and thawing injury than myeloid elements and/or that it might be safer for the thawed bone marrow not to be manipulated before infusion.