Discovery of New Isotope

The new isotope ^{241}U was synthesized and systematic atomic mass measurements of nineteen neutron-rich Pa-Pu isotopes were performed in the multinucleon transfer reactions of the ^{238}U+^{198}Pt system at the KISS facility. The present experimental results demonstrate the crucial role of the multinucleon transfer reactions for accessing unexplored neutron-rich actinide isotopes toward the N=152 shell gap in this region of nuclides.

Study of Quasielastic Barrier Distributions as a Step towards the Synthesis of Superheavy Elements with Hot Fusion Reactions.

The excitation functions for quasielastic scattering of ^{22}Ne+^{248}Cm, ^{26}Mg+^{248}Cm, and ^{48}Ca+^{238}U are measured using a gas-filled recoil ion separator. The quasielastic barrier distributions are extracted for these systems and are compared with coupled-channel calculations. The results indicate that the barrier distribution is affected dominantly by deformation of the actinide target nuclei, but also by vibrational or rotational excitations of the projectile nuclei, as well as neutron transfer processes before capture. From a comparison between the experimental barrier distributions and the evaporation residue cross sections for Sg (Z=106), Hs (108), Cn (112), and Lv (116), it is suggested that the hot fusion reactions take advantage of a compact collision, where the projectile approaches along the short axis of a prolately deformed nucleus. A new method is proposed to estimate the optimum incident energy to synthesize unknown superheavy nuclei using the barrier distribution.

Chronic Basophilic Leukaemia in a Dog.

A 13-year-old neutered female mixed-breed dog with a clinical history of emaciation, inappetence and vomiting for 2 months was presented. Blood tests showed marked leucocytosis with increased neutrophil and basophil count, mild thrombocytosis and anaemia. Seven days after the initial visit, the dog died and was submitted for necropsy examination. Grossly, the bone marrow was red in colour and hepatomegaly and splenomegaly with discolouration were observed. A bone marrow smear showed an increased proportion of basophilic lineage cells. Histologically, the bone marrow showed high cellular density and numerous basophilic lineage cells with a round or segmented nucleus. The cytoplasm contained basophilic granules exhibiting metachromasia on toluidine blue staining. Immunohistochemically, the neoplastic basophils were diffusely positive for vimentin and myeloperoxidase, but negative for CD3, BLA36, CD163, CD204 and c-kit. The immunohistochemical features of neoplastic basophils that had invaded the liver and spleen were similar to those of the basophils in the bone marrow. Based on the clinicopathological and histopathological findings, chronic basophilic leukaemia was diagnosed. The present case study provides insights into the pathological features of chronic basophilic leukaemia in dogs.

First Direct Mass Measurements of Nuclides around Z=100 with a Multireflection Time-of-Flight Mass Spectrograph.

The masses of ^{246}Es, ^{251}Fm, and the transfermium nuclei ^{249-252}Md and ^{254}No, produced by hot- and cold-fusion reactions, in the vicinity of the deformed N=152 neutron shell closure, have been directly measured using a multireflection time-of-flight mass spectrograph. The masses of ^{246}Es and ^{249,250,252}Md were measured for the first time. Using the masses of ^{249,250}Md as anchor points for α decay chains, the masses of heavier nuclei, up to ^{261}Bh and ^{266}Mt, were determined. These new masses were compared with theoretical global mass models and demonstrated to be in good agreement with macroscopic-microscopic models in this region. The empirical shell gap parameter δ_{2n} derived from three isotopic masses was updated with the new masses and corroborates the existence of the deformed N=152 neutron shell closure for Md and Lr.

Nuclear chemistry. Synthesis and detection of a seaborgium carbonyl complex.

Experimental investigations of transactinoide elements provide benchmark results for chemical theory and probe the predictive power of trends in the periodic table. So far, in gas-phase chemical reactions, simple inorganic compounds with the transactinoide in its highest oxidation state have been synthesized. Single-atom production rates, short half-lives, and harsh experimental conditions limited the number of experimentally accessible compounds. We applied a gas-phase carbonylation technique previously tested on short-lived molybdenum (Mo) and tungsten (W) isotopes to the preparation of a carbonyl complex of seaborgium, the 106th element. The volatile seaborgium complex showed the same volatility and reactivity with a silicon dioxide surface as those of the hexacarbonyl complexes of the lighter homologs Mo and W. Comparison of the product's adsorption enthalpy with theoretical predictions and data for the lighter congeners supported a Sg(CO)6 formulation.

K-Cl cotransporter expression in the human kidney.

The K-Cl cotransporter protein KCC1 is a membrane transport protein that mediates the coupled, electroneutral transport of K and Cl across plasma membranes. The precise cell type(s) in the kidney that express the K-Cl cotransporter have remained unknown. The aim of the present investigation was to define the distribution of KCC1 mRNA in the human kidney. We used in situ hybridization with a nonradioactive digoxigenin-labeled riboprobe. We identified abundant KCC1 mRNA expression in the epithelial cells throughout the distal and proximal renal tubular epithelium. The transporter was also expressed in glomerular mesangial cells and endothelial cells of the renal vessels. These findings suggest that the K-Cl cotransporter may have an important role in transepithelial K and Cl reabsorption.

Urea inhibits the Na-K pump in human erythrocytes.

Recent studies have established that urea alters the activity of several volume-sensitive cation transport pathways. However, it has remained unclear whether urea has any effect on transport pathways that are not volume-sensitive. We examined the effect of urea on Na-K pump in the human erythrocytes. In cells from nine subjects, 500 mM urea inhibited 52 +/- 10% of the pump activity measured as the ouabain-sensitive (OS) K influx. Urea inhibited the OS K influx reversibly, in a concentration-dependent manner. [3H] oubain binding, a measure of the number of Na-K pump sites remained unchanged with urea. Urea decreased the Vmax for ouabain-sensitive K influx, but did not alter the apparent K(m) for external K. Furthermore, urea did not alter the apparent K(m) for intracellular Na. The ion turnover per pump site was decreased in the presence of urea. Thus, physiologically relevant urea concentration inhibit the Na-K pump in human erythrocyte. The inhibition of the Na-K pump by urea suggests that the effects of urea may not be limited to volume-sensitive transporters, but may be more widespread.

Urea inhibits Na-K-2Cl cotransport in medullary thick ascending limb cells.

We examined the effect of physiological concentrations of urea (100-500 mM) on Na-K-2Cl cotransport in cultured cells from mouse medullary thick ascending limb (mTAL). Urea acutely inhibited bumetanide-sensitive K influx in mTAL cells in a concentration-dependent fashion, with a statistically significant inhibition (19%) at 100 mM and 86% inhibition at 500 mM. The effect of urea was entirely reversible and was blocked by prior treatment with okadaic acid, a phosphatase inhibitor, suggesting that urea exerts its action upstream of the phosphorylation-dephosphorylation step. Cell volume was unchanged in the presence of 500 mM urea. The number of [3H]bumetanide binding sites, a measure of the number of functioning cotransporter sites, was decreased in the presence of urea, and the decrease in bumetanide binding was proportional to the decrease in bumetanide-sensitive K influx. Urea also stimulated the Ba-sensitive swelling-activated K efflux from mTAL cells. Thus urea, in concentrations that prevail in the renal medulla, alters ion transport in mTAL cells.

Prostaglandin E2 inhibits Na-K-2Cl cotransport in medullary thick ascending limb cells.

Prostaglandin E2 (PGE2) is known to inhibit transepithelial Cl transport in medullary thick ascending limb (mTAL), but the mechanism of inhibition or the transport pathway affected has not been identified. We undertook this study to examine the effect of PGE2 on Na-K-2Cl cotransport in mouse mTAL cells in culture. In nanomolar concentrations, PGE2 inhibited the Na- and Cl-dependent, bumetanide-sensitive K influx by 45%, and this inhibition was also observed in the presence of 3 mM ouabain. Although PGE2 also inhibited ouabain-sensitive K flux, that inhibition was abolished in the presence of apical nystatin, suggesting that the pump inhibition was secondary to diminished Na entry into the cells. The effect of PGE2 was concentration dependent. Inhibition was observed at a concentration of < 1 nM, and half-maximal effect was observed at 2.5 nM. The effect of PGE2 was not mediated by an action on cytosolic Ca because cytosolic Ca was unchanged after the addition of PGE2. PGE2 reduced the maximal velocity for the cotransporter but had no effect on the affinity of the cotransporter for external Na, K, or Cl. Specific [3H]bumetanide binding was reduced in the presence of PGE2, suggesting that PGE2 affected bumetanide-sensitive K influx by downregulating the number of functioning Na-K-2Cl cotransporters. These results suggest that Na-K-2Cl cotransport in the mTAL cells may be under tonic inhibitory control of PGE2.

Transfection alters ion transport in MDCK cells.

In the course of an investigation into the effect of Tamm-Horsfall protein (THP) on ion transport, we performed stable transfection of THP into MDCK cells using the SV40 or the cytomegalovirus (CMV) promoter. As controls, we transfected MDCK cells with an "empty" plasmid containing SV40 or CMV promoter but without THP cDNA. In another set of controls, we subjected cells to transfection procedures without DNA (mock transfection). K influx was not altered in cells subjected to mock transfection procedures without DNA, but both ouabain sensitive (OS) and ouabain resistant (OR) components of K influx were diminished in cells transfected with THP cDNA using either SV40 or CMV promoter. However, K influx was also reduced in cells transfected with a control plasmid containing either the SV40 promoter alone, or the CMV promoter alone, without the THP cDNA. Thus, the transport alterations were caused by transfection and not by THP. The reduction in ouabain-sensitive K influx was accompanied by a proportional reduction in the abundance of Na-K pump units as assessed by [3H] ouabain binding. [3H] bumetanide binding, a measure of the number of functioning NaK2Cl cotransporter sites, was reduced pari passu with the reduction in bumetanide-sensitive K influx. These results highlight the possibility that alterations in properties of transfected cells may not be solely due to the presence of transfected protein, but the result of some process associated with transfection itself. Without appropriate controls to evaluate this possibility, results of transfection studies are subject to potentially faulty and misleading interpretation.

Urea inhibits NaK2Cl cotransport in human erythrocytes.

We examined the effect of urea on NaK2Cl cotransport in human erythrocytes. In erythrocytes from nine normal subjects, the addition of 45 mM urea, a concentration commonly encountered in uremic subjects, inhibited NaK2Cl cotransport by 33 +/- 7%. Urea inhibited NaK2Cl cotransport reversibly, and in a concentration-dependent fashion with half-maximal inhibition at 63 +/- 10 mM. Acute cell shrinkage increased, and acute cell swelling decreased NaK2Cl cotransport in human erythrocytes. Okadaic acid (OA), a specific inhibitor of protein phosphatase 1 and 2A, increased NaK2Cl cotransport by nearly 80%, suggesting an important role for these phosphatases in the regulation of NaK2Cl cotransport. Urea inhibited bumetanide-sensitive K influx even when protein phosphatases were inhibited with OA, suggesting that urea acted by inhibiting a kinase. In cells subjected to shrinking and OA pretreatment, maneuvers expected to increase the net phosphorylation, urea inhibited cotransport only minimally, suggesting that urea acted by causing a net dephosphorylation of the cotransport protein, or some key regulatory protein. The finding that concentrations of urea found in uremic subjects inhibited NaK2Cl cotransport, a widespread transport pathway with important physiological functions, suggests that urea is not only a marker for accumulation of other uremic toxins, but may be a significant uremic toxin itself.

The Malone antegrade continence enema for neurogenic and structural fecal incontinence and constipation.

Problems of fecal elimination are commonly encountered by the pediatric urologist and surgeon. The Malone antegrade continence enema has been described as a means to administer a large volume enema via a continent catheterizable appendicocecostomy, resulting in reliable fecal elimination. Of 22 patients undergoing this procedure 16 reported total continence 4 months or longer after surgery. Complications are relatively minor and tap water appears to be a safe solution for the antegrade continence enema. A nonrefluxing, imbricated appendicocecostomy is preferable to prevent cutaneous fecal or gas leaks.

Urea activation of K-Cl transport in human erythrocytes.

This report prompted us to examine the effect of urea on K-Cl cotransport in human erythrocytes. In human erythrocytes, urea activated K-Cl cotransport reversibly and in a concentration-dependent manner. Pretreatment with okadaic acid abolished the urea activation of transport, suggesting that exposure to urea resulted in net dephosphorylation of the transporter or a key regulator and that the action of urea was exerted proximal to the phosphorylation-dephosphorylation step. At a concentration of 200 mM, urea activated K-Cl cotransport without any delay, even in the absence of cell swelling. However, with increasing urea concentrations, an appreciable increase in lag time was observed before the final steady-state flux was reached, suggesting that urea inhibits a regulatory kinase. The latter conclusion was also supported by the finding that, at any given urea concentration, the lag time for activation was greater than the lag time for deactivation. Mg depletion activated cotransport, and urea had no additional stimulatory effect in Mg-depleted cells. In urea-pretreated cells, swelling further activated cotransport, but without any measurable delay, in contrast to a time lag of 8 min when control cells (not exposed to urea) were swollen. The latter finding suggests that urea promotes the conversion of transporters from the resting to the partially activated state. These findings raise the possibility that high concentrations of urea in the renal medulla may play a role in the decrease in cell volume that occurs during the maturation of reticulocytes and young erythrocytes, both in normal subjects and in subjects with hemoglobinopathies.

Blunt renal trauma in the pediatric population: indications for radiographic evaluation.

OBJECTIVES: The purpose of this study was to define more clearly the clinical indications for radiographic evaluation of blunt renal injury in the pediatric population. METHODS: Children evaluated for blunt abdominal trauma at the Children's Hospital of Los Angeles and Los Angeles County/University of Southern California Medical Center undergo routine physical examination, laboratory analysis, and computed tomography (CT) scan of the abdomen and pelvis regardless of urinalysis results. We retrospectively evaluated the abdominal and pelvic CT scans of 412 children sustaining blunt abdominal trauma between June 1985 and June 1990. A total of 48 children, ages 6 months to 14 years (mean 5.6 years), with CT-documented renal injuries secondary to blunt trauma were identified. The radiographic findings were correlated with clinical presentation in this group of patients. RESULTS: Of the 48 children sustaining renal injuries (12% of the group), 23 (48%) had renal contusions and 25 children (52%) sustained more serious (significant) renal injuries. Of the children with significant renal injuries, 17 (68%) had minor renal lacerations and 8 (32%) had major renal lacerations. No child sustained a renal pedicle injury. All 25 children sustaining significant renal injuries presented with hematuria: 17 (68%) had microscopic (more than 3 red blood cells per high-power field) and 8 (32%) had gross hematuria. In the 23 children with renal contusions, 4 (17%) had no hematuria, 13 (57%) had microscopic hematuria, and 6 (26%) presented with gross hematuria. Hypotension occurred in 2 of the 25 children with significant renal injuries and in 2 of 23 children with renal contusions. Fifteen of the 25 patients (60%) with significant renal injuries had associated organ injuries, and 17 of the 23 children (74%) with renal contusions had associated organ injuries. CONCLUSIONS: In adults, gross hematuria and microscopic hematuria with hypertension following blunt trauma have been correlated with significant renal injuries requiring radiographic investigation. We conclude that these clinical criteria proposed to guide the radiographic evaluation of the adult population with blunt trauma do not apply to children. In our study, the degree of hematuria did not correlate with the degree of renal injury, and significant renal injury did occur with microhematuria in the absence of hypotension. We suggest that any child with a history of blunt abdominal trauma and any evidence of hematuria should undergo abdominal and pelvic CT scanning for the proper diagnosis and staging of renal and other associated intra-abdominal injuries.

Characterization of Bacillus thuringiensis and related bacteria by ribosomal RNA gene restriction fragment length polymorphisms.

Ribosomal RNA gene restriction patterns have been determined for 43 strains of Bacillus thuringiensis representing 10 serovars and eight reference strains of B. anthracis, B. cereus and B. mycoides. Strains within a B. thuringiensis serovar produced highly related or identical ribotype patterns: in particular, 12 strains of serovar israelensis, five strains of serovar kurstaki, two strains of serovar galleriae and three strains of serovar aizawa produced ribotype patterns consistent with serotype designations. Moreover, variety tenebrionis (serotype 8a8b), a coleopteran pathogen, could be distinguished from the more common lepidopteran pathogens of this serotype (serovar morrisoni) by ribotyping. The correlation of ribotype patterns with serotype suggests a clonal population structure for B. thuringiensis.

Na+/K+/2Cl- cotransport in medullary thick ascending limb cells: kinetics and bumetanide binding.

We examined the properties of Na+/K+/2Cl- cotransport in cultured mouse mTAL cells with respect to its kinetics, the contribution of K/K exchange to K fluxes mediated by the cotransporter, and [3H]bumetanide binding and turnover numbers in media with varying osmolality. The addition of bumetanide, the replacement of external Na+ or the replacement of external Cl- resulted in an almost identical (approx. 50%) decrease in K+ influx, suggesting that Na(+)-dependent, Cl(-)-dependent, BS K+ influx was a measure of Na+/K+/2Cl- cotransport. The kinetics of the BS K+ influx revealed a high affinity for external Na+ (apparent Km 7 mM) and external K+ (apparent Km 1.3 mM), but a very low affinity for external Cl- (apparent Km 67 mM with a two-site model). Of interest was the finding that none of the K+ (86Rb+) efflux was sensitive to bumetanide, suggesting the absence of cotransport mediated K/K exchange in this cell type. Specific [3H]bumetanide binding was a saturable function of free bumetanide concentration with a Kd of 0.20 microM and maximum binding (Bmax) of 0.63 pmol/mg, or about 53,000 sites per cell. Simultaneous transport and bumetanide binding assays yielded a turnover number of 255 min-1. The omission of external Na+, K+ or Cl- reduced specific [3H]bumetanide binding to values indistinguishable from zero. Changing medium osmolarity resulted in a co-ordinate change in BS K+ influx and bumetanide binding, with a monotonic increase in both transport and bumetanide binding with increase in osmolality from 200 to 400 mosmol/kg. About 85% of the cotransporter sites were located on the apical side, as in the intact mTAL tubule. The simultaneous measurement of BS ion transport and [3H]bumetanide binding in the mTAL cell may provide valuable insights into the regulation of Na+/K+/2Cl- cotransport in this nephron segment.

Effect of membrane potential on K-Cl transport in human erythrocytes.

We examined whether swelling-activated K-Cl cotransport is electrogenic in human erythrocytes. Baseline membrane potential, measured by the change in fluorescence of the carbocyanine dye diS-C3-5, was not different in hypotonically swollen (-7.6 mV) or isosmotically swollen cells (-9.5 mV). We used hemisodium, a new highly selective Na ionophore, in varying concentrations, in the presence of a fixed outwardly directed Na gradient (intracellular Na, 75 mM; external Na, 1 mM) to vary membrane potential over a wide range despite identical K and Cl concentrations. The membrane potential varied between -8 and -90 mV. K influx increased slightly with hyperpolarization in swollen and nonswollen cells. However, the difference between the two fluxes, swelling-activated K influx, a measure of K-Cl cotransport, was unaffected by voltage changes, as was swelling-activated K efflux. We conclude that K-Cl cotransport in human erythrocytes is electroneutral and by inference has a 1:1 stoichiometry.

Hemisodium, a novel selective Na ionophore. Effect on normal human erythrocytes.

Hemisodium is a novel Na ionophore that belongs to the class of compounds called cryptands. These compounds possess an electron-rich cavity for binding of cations and are conformationally organized during synthesis to favor the selective binding of one cation over another. In media containing 145 mM NaCl and 5 mM KCl, hemisodium (10(-5) M) increased erythrocyte Na content from 23 to 345 mmol/kg.dry cell solid (dcs) over 4 h and increased water content from 1.8 to 3.5 liter/kg.dcs over the same period. K content decreased somewhat over the same time period, but this fall in K content was prevented entirely by incubation in either low Na media (to prevent net Na entry) or in Cl free media. Thus, the decrease in K content in high NaCl media was due to cell swelling, which activated KCl cotransport, and not due to a direct action of hemisodium on K permeability. Hemisodium-mediated Na transport was conductive, because erythrocyte membrane potential (Vm), determined by diS-C3-5 fluorescence, changed from -9 to +22 mV in high Na media in the presence of hemisodium and DIDS. In cells equilibrated with sulfamate, an anion with low conductive permeability, Vm changed 54 mV per 10-fold change in external Na concentration with the addition of hemisodium. In contrast, a 10-fold change in the external concentration of K, Rb, Cs, or T1 failed to alter Vm in the presence of hemisodium, suggesting a high Na specificity of the ionophore. Na conductance determined from net fluxes increased from 0.04 to 5.2 microS/cm2 with 10 microM hemisodium, and with that concentration the ratio of Na to K conductance was 45:1. Among the Na ionophores available so far, hemisodium appears to have the greatest specificity. Hemisodium may be a valuable tool in membrane transport studies.

The effects of extracorporeal shock wave lithotripsy on renal growth, function and arterial blood pressure in an animal model.

The long-term effects of extracorporeal shock wave lithotripsy (ESWL*) on children treated for renal calculi are unclear. To study the long-term bio-effects of this mode of treatment on the immature animal we evaluated 30 New Zealand white rabbits at 7 weeks of age for weight, serum blood urea nitrogen and creatinine, and arterial blood pressure after which they underwent left nephrectomy. Each group of 5 rabbits received ESWL of varying levels (500 to 3,000 shock waves) to the remaining right kidney using the Northgate SD3 lithotriptor (spark gap mediated). One control group received no shock waves. At maturity (16 weeks) the aforementioned parameters were measured again, and the kidneys and any grossly abnormal adjacent organs were examined. We found no significant change in total animal growth, renal growth, renal function or perirenal organs in the post-ESWL groups versus the control group. All post-ESWL groups had an increase in mean arterial blood pressure versus the control group with 3 of 6 groups showing significant increases (p less than 0.05). Histological renal changes, seen at all energy levels of ESWL delivered, included interstitial fibrosis, tubular atrophy, glomeruli destruction, capsular thickening, perivascular fibrosis and mild arteriole wall thickening. Changes were proportional to the number of shocks received. We conclude that ESWL delivered to immature animals does not significantly affect renal growth and function but it can cause significant permanent histological renal changes even at low doses and may result in an increase in adult mean arterial blood pressure.

Role of protein phosphatase in activation of KCl cotransport in human erythrocytes.

We investigated the effects of okadaic acid, a novel highly specific inhibitor of protein phosphatases on swelling-activated transport in human erythrocytes. Nanomolar concentrations of this compound inhibited swelling-activated K transport. Complete inhibition of this transport was observed at 1 microM. Analysis of the time course of activation of K transport upon swelling revealed that okadaic acid not only decreased the final steady-state flux but also markedly increased the time lag for activation. These results suggest that okadaic acid decreases the rate constant for the conversion of KCl transporters from the resting to the active form. Okadaic acid also inhibited N-ethylmaleimide (NEM)-stimulated K transport, and this inhibition was also observed when cells were first treated with NEM before exposure to okadaic acid. The latter finding suggests that NEM activation of KCl transport is reversible and that a later step for this activation may involve the net dephosphorylation of the KCl transport protein. These results provide the first evidence that activation of KCl cotransport in human erythrocytes is regulated by phosphoprotein phosphatase.