Analysis of sister chromatid exchanges in lymphocytes cultured from 71 healthy men

Sister chromatid exchanges (SCE) were analyzed in peripheral blood lymphocytes from a select group of 71 healthy men, 56 nonsmokers and 15 cigarette smokers. In addition to estimating baseline SCE, data were examined to seek relationships of SCE frequencies to age and smoking. The baseline value of 7.53 SCE per cell from the 56 nonsmokers was within the range (5.60 to 9.10 SCE/cell) reported for other human populations. No relationship was found between the mean SCE frequency per cell and age. However, a significant increase in the SCE mean value was observed in smokers as compared to nonsmokers. The results of this study are compared with those of other reports on SCE effects of age and smoking.Abbreviations BUdR 5-bromo,2-deoxyuridine - SCE sister chromatid exchange     

Evaluation of culture media for effects on cell cycle kinetics and incidence of chromosomal aberrations in human blood cells

Peripheral blood samples from 17 apparently healthy male volunteers were set up in duplicate cultures using three commercially available media: Eagle's MEM, RPMI 1640, and TC 199. BUdR (5-bromo,2-deoxyuridine) (10 micrograms/mL) was added to one of the cultures from each person in each medium after 24 h of culture initiation. All cultures were harvested at 72 h of incubation in the presence of colcemid. RPMI 1640 stimulated the highest mitotic activity in both BUdR-treated and untreated cultures. Higher numbers of first division metaphases corresponded with the higher frequency of chromosome-type aberrations in cultures with Eagle's MEM as compared with RPMI 1640 media. On the other hand, higher numbers of chromatid-type aberrations were present in cultures with TC 199 as compared with those with Eagle's MEM. When the chromosome- and chromatid-type aberration data were pooled to score total cytogenetic abnormalities, an influence of the medium was demonstrable. While cultures with Eagle's MEM and TC 199 had the greater number of first division cells, third of subsequent division cells were most prevalent in RPMI 1640 cultures. It is inferred that the length of the cell cycle, the mitotic index, and to some degree the incidence of spontaneous cytogenetic abnormalities are variable attributes of culture media.     

Total cholesterol concentration in relation to superovulatory responses in crossbred cows

Blood serum total cholesterol levels of crossbred Taur-indicus donor cows (n=22), in their 1st to 4th parity, were studied as an indicator of embryo yield. These cows were superovulated either with FSH or PMSG + anti-PMSG on the 12th day of the synchronized estrous cycle. The total and transferable number of embryos did not differ significantly between the treatment groups. The number of corpora lutea and total and transferable embryos in donors having total cholesterol levels <140 mg/dl were significantly (P < 0.05) lower than those of cows having >140 mg/dl, indicating that low total cholesterol levels might adversely affect superovulatory response. Thus, estimation of total cholesterol concentrations of potential donors can be a useful tool for predicting superovulatory responses.     

Fast optimal genome tiling with applications to microarray design and homology search.

In this paper, we consider several variations of the following basic tiling problem: given a sequence of real numbers with two size-bound parameters, we want to find a set of tiles of maximum total weight such that each tiles satisfies the size bounds. A solution to this problem is important to a number of computational biology applications such as selecting genomic DNA fragments for PCR-based amplicon microarrays and performing homology searches with long sequence queries. Our goal is to design efficient algorithms with linear or near-linear time and space in the normal range of parameter values for these problems. For this purpose, we first discuss the solution to a basic online interval maximum problem via a sliding-window approach and show how to use this solution in a nontrivial manner for many of the tiling problems introduced. We also discuss NP-hardness results and approximation algorithms for generalizing our basic tiling problem to higher dimensions. Finally, computational results from applying our tiling algorithms to genomic sequences of five model eukaryotes are reported.     

Drug-Induced Changes in Blood Pressure Lead to Changes in Extracellular Concentrations of Epinephrine, Dihydroxyphenylacetic Acid, and 5-Hydroxyindoleacetic Acid in the Rostral Ventrolateral Medulla of the Rat

Neurochemical changes in the extracellular fluid of the rostral ventrolateral medulla (RVLM) were produced by changes in arterial blood pressure. Blood pressure was raised or lowered with systemic infusions of phenylephrine or nitroprusside and neurochemicals were recovered from RVLM by in vivo microdialysis. A dialysis probe 300 microns in diameter and 500 microns in length was stereotaxically implanted in the RVLM of the urethane-anesthetized rat. Sterile physiological Ringer's solution was perfused at a rate of 1.5 microliter/min. The perfusate was collected under ice-cold conditions every 15 min for the assay of epinephrine, dihydroxyphenylacetic acid (DOPAC), 5-hydroxyindoleacetic acid (5-HIAA), ascorbic acid, and uric acid. After stable baseline neurochemical concentrations were achieved, animals were infused with phenylephrine or nitroprusside intravenously to raise or lower the blood pressure. Increasing blood pressure 50 mm Hg above the baseline value by phenylephrine led to a significant reduction in heart rate and a reduction in extracellular epinephrine and DOPAC concentrations. The 5-HIAA concentration was increased during the hypertensive drug infusion. There were no changes in the concentrations of ascorbic acid or uric acid. Hypotension produced by nitroprusside (-20 mm Hg) led to neurochemical changes which were the reciprocal of those seen during hypertension. During hypotension, heart rate increased as did the extracellular fluid epinephrine concentration. The 5-HIAA concentration fell with hypotension and remained depressed following the nitroprusside infusion. Ascorbic acid and uric acid concentrations did not change during hypotension but ascorbic acid did increase after the nitroprusside infusion stopped. These data provide direct evidence that epinephrine release in RVLM is linked to changes in systemic blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)     

T cell induction of precursor B cells: Temporal separation of helper T cell functional activities

Summary The temporal relationships involved in T cell induction of immunoglobulin-secreting B cells have been studied by employing a pulse label technique, in vitro. It was shown that addition of rabbit thymocytes or splenic T cells to B cell-enriched splenocyte populations at the time of initiation of cultures resulted in a marked enhancement in induction of immunoglobulin-secreting cells. However, even a two-hour delay in the addition of thymus cells was sufficient to reduce substantially the extent of induction when measured 70 hours later. Besides this early requirement for thymocytes, a late requirement was also detectable. Thus, thymus cells and splenocyte populations upon being mixed, subsequent to being cultured separately for 72 hours, yielded a several-fold enhancement in [³H]-immunoglobulin secreted during the course of a 90-minute labeling period with [³H]-leucine. Moreover, both the early and late thymocyte effects were lost after treatment with anti-thymocyte serum and complement.The thymocyte-mediated enhancement of immunoglobulin secretion by splenocytes that occurs late in the induction process was detected with spleen cells cultured for two or three days but not with freshly-isolated splenocytes. Although the rate of appearance of extracellular immunoglobulins was markedly enhanced by fresh thymus cells, the rate of appearance of intracellular immunoglobulins in such spleen cells was unchanged. The secretion-stimulating (secretagogue) activity of thymocytes appeared to be specific in that thymus cells were without effect on the rate of secretion of serum albumin by liver cells.In regard to the induction of immunoglobulin-secreting cells, both B and T cell-enriched population's were sensitive to mitomycin C treatment performed before initiation of cell culture, indicating that not only B cells but also T cells undergo some form of differentiation or maturation prior to functioning in the induction of immunoglobulin-producing cells. It should be noted in this context that the late T cell requirement was unaffected by prior mitomycin C treatment of thymocytes. On the other hand, thymocytes heated at 60°C for 5 minutes did not enhance immunoglobulin secretion when added at any time and the late thymocyte requirement could not be replaced with medium in which thymocytes had been previously cultured.     

Mutagenic effects of sodium azide in Drosophila melanogaster.

The mutagenic effects of sodium azide (NaN3) were studied at low pH in male Drosophila melanogaster using the sex-linked recessive-lethal test. No significant increase in the mutation frequency was observed after abdominal injection of azide solutions buffered at either pH 3.8 OR 4.6. However, a weak mutagenic effect was noticed in the flies fed for 3 days on 0.1 mM azide (pH 4.6) solution.     

A novel early effect of concanavalin A on thymocytes.

Concanavalin A, added to freshly isolated rabbit thymocytes, markedly enhanced the extracellular appearance of non-immunoglobulin proteins. Time course studies revealed that the onset of enhancement occurred virtually without delay. The effect appeared to be restricted only to certain of the thymus-derived cells because thymocytes obtained from rabbits treated with hydrocortisone, as well as splenocytes derived from untreated rabbits essentially did not exhibit the enhancement. Stimulation by concanavalin A was specific in that pokeweed mitogen and lipopolysaccharide were without effect and also in that α-methyl-mannoside, but not galactose, abrogated the concanavalin A-mediated enhancement. Experiments with mouse thymocytes demonstrated that the cells which responded to concanavalin A were primarily cells that bear the θ-antigen on their surface (T-cells).