Differential effects of positive and negative proliferative stimuli on murine cytolytic and helper T-cell clones

Studies were performed to determine whether substances could be identified which exhibited differential regulatory effects--either positive or negative--on the growth of murine alloreactive cytolytic (Tc) and helper (Th) cloned T-cell lines. The following lines of evidence suggested that Tc and Th proliferate in response to the same growth factor (GF). (1) When GF-containing fluids from cultures of phorbol myristic acetate (PMA)-activated EL4 thymoma were fractionated by a variety of biochemical techniques. Tc and Th eluted together. (2) Absorption of GF-containing supernatants with either cloned Tc or cloned Th depleted GF activity for each to a similar extent, and GF eluted from either Tc or Th to which it had adsorbed supported the proliferation of Tc and Th equally well. (3) Lectin-depleted supernatants from cultures of concanavalin A (Con A)-activated Th stimulated the proliferation of Th as well as Tc. (4) Recombinant human interleukin (IL-2) supported the growth of Tc and Th with equal efficiency. On the other hand, the following observations indicated that Tc and Th differed in their responses to inhibitors of GF-driven proliferation. (1) Con A at greater than or equal to 0.3 micrograms/ml inhibited the GF-driven proliferation of each of three Th lines but not either of two Tc lines. To the contrary, Con A enhanced GF-dependent proliferation of Tc. (2) Like Con A, allogeneic splenocytes selectively depressed GF-driven proliferation of Th but not Tc. (3) A substance generated during the acid elution of GF from cells, possibly a modified fetal calf serum component, greatly reduced the GF-driven proliferation of Tc but not Th. These results suggest that differential control of the proliferation of Tc and Th in cellular immune responses may be achieved via negative regulatory signals and raise the possibility that substances which can selectively depress the proliferation of specific T-cell subsets might be found which would be of therapeutic value.     

A high affinity,calmodulin-responsive (Ca2+ + Mg2+)-ATPase in isolated bone cells

Although acute alterations in Ca²⁺ fluxes may mediate the skeletal responses to certain humoral agents, the processes subserving those fluxes are not well understood. We have sought evidence for Ca²⁺-dependent ATPase activity in isolated osteoblast-like cells maintained in primary culture. Two Ca²⁺-dependent ATPase components were found in a plasma membrane fraction: a high affinity component (half-saturation constant for Ca²⁺ of 280 nM, $\text{V}{}_{\mathrm{<mtext>max</mtext>}}$ of 13.5 nmol/mg per min) and a low affinity component, which was in reality a divalent cation ATPase, since Mg²⁺ could replace Ca²⁺ without loss of activity. The high affinity component exhibited a pH optimum of 7.2 and required Mg²⁺ for full activity. It was unaffected by potassium or sodium chloride, ouabain or sodium azide, but was inhibited by lanthanum and by the calmodulin antagonist trifluoperazine. This component was prevalent in a subcellular fraction which was also enriched in 5′-nucleotidase and adenylate cyclase activities, suggesting the plasma membrane as its principal location. Osteosarcoma cells, known to resemble osteoblasts in their biological characteristics and responses to bone-seeking hormones, contained similar ATPase activities. Inclusion of purified calmodulin in the assay system caused small non-reproducible increases in the Ca²⁺-dependent ATPase activity of EGTA-washed membranes. Marked, consistent calmodulin stimulation was demonstrated in membranes exposed previously to trifluoperazine and then washed in trifluoperazine-free buffer. These results indicate the presence of a high affinity, calmodulin-sensitive Ca²⁺-dependent ATPase in osteoblast-like bone cells. As one determinant of Ca²⁺ fluxes in bone cells, this enzyme may participate in the hormonal regulation of bone cell function.     

INVITED SPECIAL PAPER: History of the botanical teaching laboratory in the United States

The establishment of teaching laboratories for botany in the United States was strongly influenced in the early part of the 19th century by the founding of a laboratory of natural history at the Rensselaer School by Amos Eaton who inspired numerous educators, particularly women. By midcentury and later, botany programs were established at land-grant colleges and the so-called “new Botany” movement spread from them. In the latter part of the century additional changes were brought about by the influence of German laboratory activity and botanists’ reactions to the introduction of the Huxley-Martin biology programs to America. During these times, Americans were improving their own manufactured microscopes, laboratory supplies, and equipment capabilities. By the beginning of the 20th century, laboratory teaching of botanical subjects was widely accepted as normal in universities and colleges, as well as in some high schools.     

The effect of cell density on the expression of cell adhesive properties in a cloned rat astrocytoma (C-6)

The cell-cell adhesion characteristic of C-6 astrocytoma cells changes as a function of cell density. Cell suspensions prepared from monolayers having a density lower than 1 × 10⁵ cells/cm² show maximal affinity for plasma membranes and cells obtained from monolayers at densities greater than 1 × 10⁶ cells/cm² shows minimal affinity for plasma membranes. The adhesive component retained on plasma membranes is present at essentially equal levels in membranes prepared from cells at different density. This modulation in cell surface affinity appears to be due to cell-cell contact and appears to represent a suitable model for the study of the modulation of cell-cell adhesion as a result of cell contact.     

A new method for determination of elastolytic activity using (14C) labeled elastin and its application to leukocytic elastase.

A new, highly sensitive and specific assay for elastolytic activity is described which employs insoluble elastin randomly labeled with [¹⁴C]. The substrate was prepared by labeling amino groups of the protein in vitro with [¹⁴C] methyl groups by reductive alkylation. The substrate was used to quantitate elastolytic activity from human leukocytes and to compare leukocytic elastase with pancreatic elastase. Purified human leukocytic elastase was approximately one-fourth as active as pancreatic elastase. Similar difference between leukocytic elastase and pancreatic elastase activities was found when the enzymes were tested against succinyl-L-alanyl-L-alanyl-L-alanine-p-nitroanilide, but not when t-BOC-L-alanine-p-nitrophenyl ester was used.     

Quality control and integration of genotypes from two calling pipelines for whole genome sequence data in the Alzheimer's disease sequencing project

The Alzheimer's Disease Sequencing Project (ADSP) performed whole genome sequencing (WGS) of 584 subjects from 111 multiplex families at three sequencing centers. Genotype calling of single nucleotide variants (SNVs) and insertion-deletion variants (indels) was performed centrally using GATK-HaplotypeCaller and Atlas V2. The ADSP Quality Control (QC) Working Group applied QC protocols to project-level variant call format files (VCFs) from each pipeline, and developed and implemented a novel protocol, termed “consensus calling,” to combine genotype calls from both pipelines into a single high-quality set. QC was applied to autosomal bi-allelic SNVs and indels, and included pipeline-recommended QC filters, variant-level QC, and sample-level QC. Low-quality variants or genotypes were excluded, and sample outliers were noted. Quality was assessed by examining Mendelian inconsistencies (MIs) among 67 parent-offspring pairs, and MIs were used to establish additional genotype-specific filters for GATK calls. After QC, 578 subjects remained. Pipeline-specific QC excluded ~12.0% of GATK and 14.5% of Atlas SNVs. Between pipelines, ~91% of SNV genotypes across all QCed variants were concordant; 4.23% and 4.56% of genotypes were exclusive to Atlas or GATK, respectively; the remaining ~0.01% of discordant genotypes were excluded. For indels, variant-level QC excluded ~36.8% of GATK and 35.3% of Atlas indels. Between pipelines, ~55.6% of indel genotypes were concordant; while 10.3% and 28.3% were exclusive to Atlas or GATK, respectively; and ~0.29% of discordant genotypes were. The final WGS consensus dataset contains 27,896,774 SNVs and 3,133,926 indels and is publicly available.     

Dietary nitrate's effects on exercise performance in heart failure with reduced ejection fraction (HFrEF)

Heart failure with reduced ejection fraction (HFrEF) is a deadly and disabling disease. A key derangement contributing to impaired exercise performance in HFrEF is decreased nitric oxide (NO) bioavailability. Scientists recently discovered the inorganic nitrate pathway for increasing NO. This has advantages over organic nitrates and NO synthase production of NO. Small studies using beetroot juice as a source of inorganic nitrate demonstrate its power to improve exercise performance in HFrEF. A larger-scale trial is now underway to determine if inorganic nitrate may be a new arrow for physicians' quiver of HFrEF treatments.     

Deficiency of mouse mast cell protease 4 mitigates cardiac dysfunctions in mice after myocardium infarction

Mouse mast cell protease-4 (mMCP4) is a chymase that has been implicated in cardiovascular diseases, including myocardial infarction (MI). This study tested a direct role of mMCP4 in mouse post-MI cardiac dysfunction and myocardial remodeling. Immunoblot and immunofluorescent double staining demonstrated mMCP4 expression in cardiomyocytes from the infarct zone from mouse heart at 28 day post-MI. At this time point, mMCP4-deficient Mcpt4^?/? mice showed no difference in survival from wild-type (WT) control mice, yet demonstrated smaller infarct size, improved cardiac functions, reduced macrophage content but increased T-cell accumulation in the infarct region compared with those of WT littermates. mMCP4-deficiency also reduced cardiomyocyte apoptosis and expression of TGF-β1, p-Smad2, and p-Smad3 in the infarct region, but did not affect collagen deposition or α-smooth muscle actin expression in the same area. Gelatin gel zymography and immunoblot analysis revealed reduced activities of matrix metalloproteinases and expression of cysteinyl cathepsins in the myocardium, macrophages, and T cells from Mcpt4^?/? mice. Immunoblot analysis also found reduced p-Smad2 and p-Smad3 in the myocardium from Mcpt4^?/? mice, yet fibroblasts from Mcpt4^?/? mice showed comparable levels of p-Smad2 and p-Smad3 to those of WT fibroblasts. Flow cytometry, immunoblot analysis, and immunofluorescent staining demonstrated that mMCP4-deficiency reduced the expression of proapoptotic cathepsins in cardiomyocytes and protected cardiomyocytes from H₂O₂-induced apoptosis. This study established a role of mMCP4 in mouse post-MI dysfunction by regulating myocardial protease expression and cardiomyocyte death without significant impact on myocardial fibrosis or survival post-MI in mice.     

Period-four oscillations of the flash-induced oxygen formation in photosynthesis*

In this minireview, the earlier researches that led to the discovery of the period-four oscillations of the flash-induced oxygen formation are presented. It also includes the background of the classical model proposed by Bessel Kok, in which the formation of oxygen requires the sequential accumulation of four positive charges on the donor side of the same reaction center. This revised version was published online in August 2006 with corrections to the Cover Date.     

A comparative analysis of heat waves and associated mortality in St. Louis, Missouri – 1980 and 1995

 This research investigates heat-related mortality during the 1980 and 1995 heat waves in St. Louis, Missouri. St. Louis has a long history of extreme summer weather, and heat-related mortality is a public health concern. Heat waves are defined as days with apparent temperatures exceeding 40.6°C (105°F). The study uses a multivariate analysis to investigate the relationship between mortality and heat wave intensity, duration, and timing within the summer season. The heat wave of 1980 was more severe and had higher associated mortality than that of 1995. To learn if changing population characteristics, in addition to weather conditions, contributed to this difference, changes in population vulnerability between 1980 and 1995 are evaluated under simulated heat wave conditions. The findings show that St. Louis remains at risk of heat wave mortality. In addition, there is evidence that vulnerability has increased despite increased air-conditioning penetration and public health interventions. Received: 12 August 1997 / Revised: 12 January 1998 / Accepted: 13 February 1998