The SAD1/RAD53 protein kinase controls multiple checkpoints and DNA damage-induced transcription in yeast

Inhibition of DNA synthesis prevents mitotic entry through the action of the S-phase checkpoint. We have isolated S-phase arrest-defective (sad) mutants that show lethality in the presence of the DNA synthesis inhibitor hydroxyurea (HU). Several of these mutants show phenotypes consistent with inappropriate mitotic entry in the presence of unreplicated DNA, indicating a defect in the S-phase checkpoint. sad1 mutants are additionally defective for the G1 and G2 DNA damage checkpoints, and for DNA damage-induced transcription of RNR2 and RNR3. The transcriptional response to DNA damage requires activation of the Dun1 protein kinase. Activation of Dun1 in response to replication blocks or DNA damage is blocked in sad1 mutants. The HU sensitivity of sad1 mutants is suppressed by mutations in CKS1, a subunit of the p34CDC28 kinase, further establishing a link between cell cycle progression and lethality. sad1 mutants are allelic to rad53, a radiation-sensitive mutant. SAD1 encodes an essential protein kinase. The observation that SAD1 controls three distinct checkpoints suggests a common mechanism for cell cycle arrest at these points. Together, these observations implicate protein phosphorylation in the cellular response to DNA damage and replication blocks.

A novel mutation in the cystic fibrosis gene in patients with pulmonary disease but normal sweat chloride concentrations

BACKGROUND

Many patients with chronic pulmonary disease similar to that seen in cystic fibrosis have normal (or nondiagnostic) sweat chloride values. It has been difficult to make the diagnosis of cystic fibrosis in these patients because no associated mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene has been identified.

METHODS

We evaluated 23 patients with pulmonary disease characteristic of cystic fibrosis but with sweat chloride concentrations in the normal range. Mutations in the CFTR gene were sought by direct sequencing of polymerase chain reaction-amplified nasal epithelial messenger RNA and by testing the functioning of affected epithelium.

RESULTS

A cytidine phosphate guanosine dinucleotide C-to-T point mutation in intron 19 of the CFTR gene, termed 3849 + 10 kb C to T, was identified in 13 patients from eight unrelated families. This mutation was found in patients from three different ethnic groups with three different extended haplotypes. The mutation leads to the creation of a partially active splice site in intron 19 and to the insertion into most CFTR transcripts of a new 84-base-pair "exon," containing an in-frame stop codon, between exons 19 and 20. Normally spliced transcripts were also detected at a level approximately 8 percent of that found in normal subjects. This mutation is associated with abnormal nasal epithelial and sweat acinar epithelial function.

CONCLUSIONS

We have identified a point mutation in intron 19 of CFTR and abnormal epithelial function in patients who have cystic fibrosis-like lung disease but normal sweat chloride values. The identification of this mutation indicates that this syndrome is a form of cystic fibrosis. Screening for the mutation should prove diagnostically useful in this population of patients.

Expression of the neurotensin gene in fetal human liver and fibrolamellar carcinoma

OBJECTIVE

This study determined whether the neurotensin gene (NT/N) is expressed in the normal adult liver and focal nodular hyperplasia (FNH) and confirmed NT/N expression in fibrolamellar carcinoma; whether NT/N or the neurotensin receptor is expressed in the fetal liver; and whether hepatic resection leads to expression of NT/N.

SUMMARY BACKGROUND DATA

Neurotensin (NT), a gut tridecapeptide localized in the gastrointestinal tract of the adult to the small bowel, is an important hormone-regulating gut motility, secretion, and mucosal growth. Expression of the NT/N gene has been identified in fibrolamellar carcinomas, but NT/N is not known to be expressed in the normal liver.

METHODS

Sensitive ribonuclease (RNase) protection assays were used to determine whether NT/N is expressed in fibrolamellar carcinoma, FNH, or healthy fetal and adult livers. The authors also determined whether the receptor for NT was present in the fetal liver and whether liver resection and subsequent regeneration could lead to re-expression of NT/N in the rat.

RESULTS

Neurotensin is expressed in fibrolamellar carcinoma and in the fetal human liver, but not in the adult liver or the samples of FNH. In addition, the authors were not able to detect expression of the NT receptor in the fetal liver and did not identify NT/N gene activation in the regenerating liver of the rat.

CONCLUSIONS

The NT/N gene will be a useful molecular marker to differentiate fibrolamellar carcinoma from other liver tumors. The finding of NT/N expression in the fetal liver suggests a stem cell descendant that is common to both the liver and gut. The absence of NT/N expression in the regenerating liver suggests that NT does not play a role in this rapid growth process.

Translocation (8;21) in oligoblastic leukemia: is this a true myelodysplastic syndrome?

An 8;21 translocation with trisomy 4 is described in a 36-year-old Chinese woman who presented with an oligoblastic leukemia with myelodysplastic (MDS) features. Progression to acute myeloblastic leukemia (AML) occurred 3 months after presentation. She died of septicemia without remission. Through a review of the data in 10 cases of oligoblastic leukemia with t(8;21) in the literature, we make the following comments. (i) Oligoblastic leukemia with t(8;21) represents 2-3% of cases with this karyotype. (ii) Such cases behave in a similar manner to de novo AML. (iii) The presence of features of MDS has no affect on the behaviour of the disease. (iv) Such cases should be treated without delay with intensive chemotherapy.

Role of FGFs in skeletal muscle and limb development

Fibroblast growth factors (FGFs) are a family of nine proteins that bind to three distinct types of cell surface molecules: (i) FGF receptor tyrosine kinases (FGFR-1 through FGFR-4); (ii) a cysteine-rich FGF receptor (CFR); and (iii) heparan sulfate proteoglycans (HSPGs). Signaling by FGFs requires participation of at least two of these receptors: the FGFRs and HSPGs form a signaling complex. The length and sulfation pattern of the heparan sulfate chain determines both the activity of the signaling complex and, in part, the ligand specificity for FGFR-1. Thus, the heparan sulfate proteoglycans are likely to play an essential role in signaling. We have recently identified a role for FGF in limb bud development in vivo. In the chick limb bud, ectopic expression of the 18 kDa form of FGF-2 or FGF-2 fused to an artificial signal peptide at its amino terminus causes skeletal duplications. These data, and the observations that FGF-2 is localized to the subjacent mesoderm and the apical ectodermal ridge in the early developing limb, suggest that FGF-2 plays an important role in limb outgrowth. We propose that FGF-2 is an apical ectodermal ridge-derived factor that participates in limb outgrowth and patterning.

Mn2+ as a contrast reagent for NMR studies of 35Cl- and 81Br- transport through model biological membranes

One major problem in using NMR to study halide ions in biological and model biological systems has been to find a contrast reagent to differentiate between halide ions in different compartments. Mn2+ is shown to be a very efficient NMR relaxation agent for the halide ions chloride and bromide and preferable to Co2+ at high magnetic fields. Its use is demonstrated in experiments in which halide ions are exchanged across the membranes of egg yolk phosphatidylcholine vesicles by the phase transfer catalysts tetrabutylammonium ion and benzyltributylammonium ion. Benzyltributylammonium ion is shown to be the more rapid anion transporter through the membrane. Valinomycin is found to cotransport ammonium ions with chloride as an ion pair at a faster rate than the phase transfer catalysts.

T-type calcium current in latent pacemaker cells isolated from cat right atrium

Whole-cell voltage clamp techniques were used to study Ca2+ currents in latent pacemaker cells isolated from cat right atrium. T-type (ICa,T) and L-type (ICa.L) Ca2+ currents were distinguished by their voltage dependence of activation, and sensitivity to channel blocking agents. In 2.7 mM [Ca]o, ICa,T activation exhibited a voltage threshold of about -50mV and maximum amplitude at -10mV, whereas ICa,L threshold was about -30mV and maximum amplitude was at +10mV. The half-maximal activation voltages of ICa,T was -31.4 +/- 0.2mV and ICa,L was -6.2 +/- 2.0mV. Overlap of the steady-state activation-inactivation curves for ICa,T showed a "window" current at voltages compatible with the late phase of diastolic depolarization. Maximum ICa,T and ICa,L current densities were 3.3 +/- 0.4pA/pF and 12.5 +/- 1.3pA/pF, respectively. ICa,T current density in working atrial muscle cells was 0.73 +/- 0.31pA/pF. Both ICa,L and ICa,T were blocked by 2mM cobalt. ICa,L but not ICa,T was blocked by 1 microM nifedipine. Nickel (Ni2+; 40 microM) inhibited ICa,T primarily at more negative voltages. In addition, Ni2+ decreased the late phase of diastolic depolarization and significantly increased pacemaker cycle length. These results indicate that latent atrial pacemaker cells exhibit ICa,T that is significantly larger in amplitude than in working atrial muscle cells. ICa,T may contribute current during the late phase of diastolic depolarization. Because latent pacemakers exhibit a more negative maximum diastolic potential, ICa,T may contribute more to latent than to primary pacemaker activity.

[Clinicopathologic and immunohistochemical studies of midline malignant reticulosis in palate]

Fourteen patients (10 males and 4 females) with midline malignant reticulosis (MMR) in palate were studied. The symptoms were most commonly swelling and ulceration. In some cases, the lesion involved nasal, maxillary sinus and facial skin, but no regional lymph nodes were involved. A necrotizing infiltration of atypical lymphoid cells (ALCs) mixed with inflammatory cells was confirmed as the histopathologic feature of MMR. In 2 of 14 cases, ALCs formed a continuous sheet in several high-power fields with a few inflammatory cells. This overlapping feature may be a transitional form between MMR and malignant lymphoma. Immunohistochemical staining results indicated that in 10 of 14 cases, ALCs were CD3 positive; in 7 of 14 cases, ALCs were UCHL1 positive; and in all 14 cases, ALCs were L26 negative. We deem MMR a T-cell lymphoma in substance, but it should be treated as a histopathologic entity distinct from malignant lymphoma.

Condition judgement of dry eye in sicca syndrome

In this paper, we presented 32 dry eyes of 16 random patients with primary Sicca Syndrome graded with rose bengal (rb), Break up time of tear film (BUT) and Schirmer 1 test (S1T). Of them, the lip biopsy and tear beta 2-M level were examined and overall studied. The results showed that the grade of dry eye was closely related with both the degree of lymphocyte infiltration of lip glands and level of tear beta 2-M, and indicated that our grading method for dry eye based on rb, BUT and S1T is depandable, and the lymphocyte infiltration of both lip and lacrymal gland may be the same qualitatively and quantitatively. so, how many lymphocytes appeared in the lip gland, how much concentration would be the tear beta 2-M Therefore judging the condition of dry eye by these 5 tests is dependable and simple too, as they need no complicated equipment.

Functional analysis of T-cell antigen 4-1BB in activated intestinal intra-epithelial T lymphocytes

The 4-1BB antigen has been recently demonstrated to be a 30 kDa inducible T-cell antigen and is expressed on the cell surface of activated splenic T cells and thymocytes. This novel T-cell antigen also associates physically with the T cell-specific protein tyrosine kinase, p56lck. We show here that the inducible T-cell antigen 4-1BB is expressed on activated intestinal intra-epithelial T lymphocytes (IEL). After activation, or in the presence of IL-2, the activated IELs showed higher levels of 4-1BB. Functional studies revealed that the activated IELs triggered with anti-4-1BB monoclonal antibody could enhance the level of IEL cytotoxicity against anti-CD3-secreting hybridoma cells. Cross-linking of anti-4-1BB antibody also enhanced the proliferation of IELs. These results suggest that the inducible antigen 4-1BB has broad biological functions which not only play a role in activated splenic T cells and thymocytes but also in the mucosal immune system.

Metabolically based treatment of stunned myocardium

Reversible myocardial ischemia is associated with a rapid decrease in contractility and prolonged postischemic ventricular dysfunction, due in part to altered intracellular calcium handling and/or contractile protein dysfunction. The maintenance of intracellular calcium homeostasis and force development by the contractile apparatus are dependent upon the free energy derived from ATP hydrolysis. This energy of hydrolysis is determined by the myocardial phosphorylation potential, an estimate of which can be made from the ratio (CrP)/(Cr) x (P(i)). Results from in vitro and in vivo studies suggest that pyruvate enhances contractility in both normal and stunned myocardium by enhancing myocardial phosphorylation potential. In regionally stunned porcine myocardium, pyruvate infusion increased recovery of regional ventricular function from 33% +/- 4% of preischemic systolic wall thickening to 81% +/- 4% and increased the (CrP)/(Cr) x (P(i)) ratio fivefold from 0.21 +/- 0.04 to 1.05 +/- 0.08. Thus, metabolic substrates that enhance myocardial energetics and ventricular function may be effective agents for attenuating postischemic ventricular function.

Delayed rectifier potassium current (IK) in latent atrial pacemaker cells isolated from cat right atrium

Whole-cell recording techniques were used to study the delayed rectifier K+ current (IK) in latent pacemaker cells isolated from cat right atrium. From a holding potential of -40 mV, depolarizing clamp steps elicited L-type Ca2+ current followed by an increasing outward current (IK). The time course of tail current amplitudes paralleled that of the time-dependent activation of outward current. Activation of IK exhibited a sigmoidal time course that was best fit by a power function where the activation variable was raised to the second power. The voltage-dependence of IK activation exhibited a sigmoidal relationship between -40 and +30 mV. The half-maximal activation voltage and slope factor were -21.9 +/- 1.3 and 13.8 +/- 0.9 mV respectively (n = 6). The fully activated I/V relationship of IK was linear between -100 and -30 mV and inwardly rectified at more positive voltages. Following IK activation, hyperpolarizations more negative than about -50 mV elicited tail currents that consisted of both IK deactivation and I(f) activation. A subtraction protocol was used to isolate IK tail currents. In 5.4 mM extracellular [K+], IK tail currents exhibited a reversal potential of -78.2 +/- 0.3 mV (n = 6). The reversal potential of IK was linearly related to log extracellular [K] and the slope was 51.5 mV per ten-fold change in extracellular [K]. At -70 mV, IK tail currents decayed as a single exponential function with a time constant of 159 +/- 16 ms (n = 6). These results indicate that latent atrial pacemakers exhibit IK activated by depolarization.(ABSTRACT TRUNCATED AT 250 WORDS)

4-1BB T-cell antigen binds to mature B cells and macrophages, and costimulates anti-mu-primed splenic B cells

4-1BB is expressed on activated murine T cells and may function as an accessory signaling molecule during T-cell activation. To identify putative 4-1BB ligands, a fusion protein consisting of the extracellular domain of 4-1BB fused to human placental alkaline phosphatase (4-1BB-AP) was constructed. Alkaline phosphatase activity could then be used as an indicator of the relative amount of bound 4-1BB. These studies indicated that 4-1BB-AP specifically bound to the surface of various mature B and macrophage cell lines. 4-1BB-AP bound at low levels to T cell lines (non-activated and anti-CD3-activated), pre-B-cell lines, and an immature macrophage cell line. 4-1BB-AP did not bind to a glial tumor cell line, HeLa cells, or COS cells. In addition, 4-1BB-AP bound at higher levels to F(ab')2 anti-mu-activated primary B cells compared to anti-CD3-activated primary T cells. Scatchard analysis indicated that the A20 B cell lymphoma expressed 3680 binding sites per cell with a Kd of 1.86 nM. Affinity cross-linking studies demonstrated that a major cell surface species of 120 kDa bound to 4-1BB-AP; 4-1BB-AP also bound to a minor species of approximately 60 kDa. The addition of paraformaldehyde-fixed SF21 cells expressing recombinant 4-1BB synergized with F(ab')2 anti-mu in inducing splenic B cell proliferation suggesting that 4-1BB may function as a regulator of B cell growth.

Convergence of quantum electrodynamics in a curved modification of Minkowski space

The interaction and total hamiltonians for quantum electrodynamics, in the interaction representation, are entirely regular self-adjoint operators in Hilbert space, in the universal covering manifold M of the conformal compactification of Minkowski space Mo. (M is conformally equivalent to the Einstein universe E, in which Mo may be canonically imbedded.) In a fixed Lorentz frame this may be expressed as convergence in a spherical space with suitable periodic boundary conditions in time. The traditional relativistic theory is the formal limit of the present variant as the space curvature vanishes.

In vitro femoral arterial responses to vasoconstrictor and vasodilator agents in endotoxin shock

The hypothesis for this study is that the decreased arterial response to catecholamines may be due to the effect of endotoxemia on vessel tone. One control ring was taken from one femoral artery of a Wistar rat and after endotoxin (ENDT) infusion (i.v. 6 mg/kg-1 hr.), one ring was removed from the contralateral artery. The post-ENDT rings were tested in four groups which were determined by the mean arterial pressure (MAP) levels at the time of dissection: 100 mmHg (120 min), 80 mmHg (270 min), 60 mmHg (300 min) or 40 mmHg (330 min). KCl, phenylephrine (PHE) and arginine-vasopressin (AVP) dose-response curves (DR) were obtained at a preload of 500 mg which allowed the maximum response in control rings. When compared at 500 mg preload the maximal active response to all agonists post-ENDT was decreased by about 50%. By increasing the preload on the ENDT rings to 800 mg, the active tension became 2.49 times the active tension of the control rings. Length-tension experiments also showed a greater response for post-ENDT rings and a greater preload at maximum response but the ring circumference was the same. In contrast the in vivo femoral artery diameters at 90 min post-ENDT (100 mmHg) were 82.6% of control. Endothelium-dependent relaxation by acetylcholine (ACh) was abolished by ENDT but endothelium-independent relaxation to nitroprusside (NP) was not affected. It is concluded that the resting tone and active tension of femoral artery smooth muscle is increased by ENDT and the decreased in vivo responsiveness to vasoconstrictor agonists may be the result of vessel constriction due to loss of endothelium. The results also suggest that in vitro comparison of vessels in studies of endotoxin shock be done at the same muscle length rather than at the same preload.

Fast gradient-based methods for Bayesian reconstruction of transmission and emission PET images

The authors describe conjugate gradient algorithms for reconstruction of transmission and emission PET images. The reconstructions are based on a Bayesian formulation, where the data are modeled as a collection of independent Poisson random variables and the image is modeled using a Markov random field. A conjugate gradient algorithm is used to compute a maximum a posteriori (MAP) estimate of the image by maximizing over the posterior density. To ensure nonnegativity of the solution, a penalty function is used to convert the problem to one of unconstrained optimization. Preconditioners are used to enhance convergence rates. These methods generally achieve effective convergence in 15-25 iterations. Reconstructions are presented of an (18)FDG whole body scan from data collected using a Siemens/CTI ECAT931 whole body system. These results indicate significant improvements in emission image quality using the Bayesian approach, in comparison to filtered backprojection, particularly when reprojections of the MAP transmission image are used in place of the standard attenuation correction factors.

[Quantitative determination of rhapontin in root of Rheum hotaoense by TLC-scanning]

The contents of rhapontin in the root of Rheum hotaoense were determined by CS-920 TLC-scanning of silica gel plate A mixture of benzene-EtOAc-EtOH (5 : 3, 5 : 1.5) was used as the developing solvent. Recovery was 100.44%, RSD 3.0%.

DUN1 encodes a protein kinase that controls the DNA damage response in yeast

DNA damage induces the expression of many genes proposed to enhance DNA repair capacities. We investigated the mechanism by which DNA damage induces transcription of RNR3, a subunit of ribonucleotide reductase. Five complementation groups of DNA-damage uninducible (dun) mutants were identified. Each is sensitive to DNA damage. dun1 mutants are also defective for RNR1 and RNR2 induction but are proficient for induction of other genes, defining the existence of at least two distinct DNA damage induction pathways. DUN1 encodes a nuclear protein kinase that is also a phosphoprotein. Phosphorylation of Dun1 increases in response to DNA damage in a Dun1-dependent manner, suggesting an increase in autophosphorylation activity. These results establish the existence of a eukaryotic SOS response regulated by protein phosphorylation.

[A study of CGRP receptor and its effect on the growth of human pancreatic carcinoma cells]

In the present studies the calcitonin gene-related peptide (CGRP) receptors were characterized by radioligand analysis and the effect of CGRP and CGRP receptor antagonist on the growth of human pancreatic carcinoma cells (PU-PAN-1) was determined by 3H-TdR incorporation assay. The results indicated that human pancreatic carcinoma cells possess distinct CGRP receptors. CGRP stimulated the growth of PU-PAN-1 tumor cells, and CGRP receptor antagonist CGRP8-37 inhibited these effects. These results suggests that CGRP receptors may play an important role in the growth of human pancreatic carcinoma cells (PU-PAN-1).

Calcium permeability of nicotinic acetylcholine receptor channels in bovine adrenal chromaffin cells

The fractional contribution of Ca to current flow through neuronal-type nicotinic acetylcholine receptor channels was determined by quantitative fluorescence microfluorimetry using fura-2. The method, which has been applied already to several types of cells and channels is described in detail here. At -70 mV and 2 mM external Ca concentration it was found that Ca contributes 2.5% to the net current. The fractional contribution was found to be voltage dependent, increasing at negative potentials e-fold for a 110 mV potential difference. Total non-specific cation current was found to have a bell-shaped dependence on external Ca concentration peaking at 2 mM.

[Detection of the direct genotyping of HSV by PCR and its primal usage in ophthalmology]

The direct genotyping of Herpes Simplex Virus (HSV) by polymerase chain reaction (PCR) was used to analysis the smears from corneas or tears of 37 cases suspected HSK. The results show that PCR is a sensitive rapid and simple method. The key procedure is taking specimens.