Mass-independent Dunham analysis of the known electronic states of platinum sulfide, PtS, and analysis of the electronic field-shift effect

Several new vibrational bands of the [12.5] Ω = 0⁺-X³Σ^- _Ω=0⁺ and the [15.9] B Ω = 0⁺-X³Σ^- _Ω=0⁺ transitions have been observed in high resolution absorption measurements recorded using Intracavity Laser Spectroscopy (ILS). These new bands have been rotationally analyzed and incorporated into a comprehensive PtS dataset that was fit to a mass-independent Dunham expression using PGOPHER. The comprehensive dataset included all reported field-free, gas phase spectroscopic data for PtS, including 32 Fourier transform microwave transitions (estimated accuracy: 1 kHz), 9 microwave/optical double resonance transitions (25 kHz), 51 millimeter and submillimeter transitions (25-50 kHz), 469 molecular beam-laser induced fluorescence transitions (0.003 cm^-1), and 4870 ILS transitions (0.005 cm^-1). The determined equilibrium constants have been used with the Rydberg-Klein-Rees method to produce potential energy curves for the four known electronic states of PtS. Isotopic shifts in electronic transition energy beyond expectations from the Born-Oppenheimer approximation were observed and treated as electronic field-shift effects due to the difference in the nuclear charge radius between Pt isotopes. The magnitude and sign of the determined field-shift parameters are rationalized through the analysis of the previously reported ab initio calculations.

The spin-forbidden a 4Σ--X 2Π1/2 transition of GeH detected in absorption using intracavity laser spectroscopy

The a ⁴Σ^--X ²Π_1/2 transition of GeH has been recorded in absorption for the first time using Intracavity Laser Spectroscopy (ILS). The GeH molecules were produced in a 0.40-0.60 A DC plasma discharge inside an aluminum hollow cathode, using 500 mTorr of Ar, 100 mTorr of H₂, and 200 mTorr of GeH₄. This cathode is located within the resonator cavity of a Coherent Verdi™ V-10 pumped dye laser. Effective path lengths for this series of measurements using the ILS method ranged from 2 to 7 km. Spectra were calibrated using the absorption spectrum of I₂ collected from an extracavity cell, the I₂ transmission spectrum from Salami and Ross, J. Mol. Spectrosc. 223(1), 157 (2005) and PGOPHER's [C. M. Western, J. Quant. Spectrosc. Radiat. Transfer 186, 221-242 (2016)] calibration feature. Differences in peak positions between calibrated experimental spectra and the reference data were on average less than ±0.002 cm^-1. All eight branches expected to have appreciable intensity for the transition have been identified, and isotopologue splitting was observed in features of 5 of the 8 identified rotational branches. Molecular constants have been obtained for the a ⁴Σ^- states of ⁷⁰GeH (20.84% abundant), ⁷²GeH (27.54% abundant), and ⁷⁴GeH (36.28% abundant). The transitions were fit using PGOPHER, holding the ground state constants fixed to the values reported by Towle and Brown [Mol. Phys. 78(2), 249 (1993)]. The constants for the a ⁴Σ^- state of ⁷⁴GeH determined by the fit are T₀ = 16 751.5524(13) cm^-1, B₀ = 6.764 912(33) cm^-1, D₀ = 0.459 60(17) × 10^-3 cm^-1, λ_SS = 9.7453(12) cm^-1, λ_D = 0.468(14) × 10^-3 cm^-1, γ = 0.077 878(84), and γ_S = -0.361(77) × 10^-3 cm^-1.

High resolution electronic spectroscopy of the A (2)Σ- - X (2)Π1/2 transition of PtN

The (2,0) vibrational band of the A (2)Σ(-) - X (2)Π1/2 transition of platinum nitride, PtN, was recorded at Doppler-limited resolution using intracavity laser absorption spectroscopy (ILS) and at sub-Doppler resolution using molecular beam laser induced fluorescence (LIF) spectroscopy. Isotopologue structure for (194)PtN, (195)PtN, and (196)PtN, magnetic hyperfine splitting due to (195)Pt (I = ½), and nuclear quadrupole splitting due to (14)N (I = 1) were observed in the spectrum. Molecular constants for the ground and excited states are derived. The hyperfine interactions are used to illuminate the nature of the A (2)Σ(-) excited electronic state.

15-deoxy-Delta12,14 prostaglandin J2-induced heme oxygenase-1 in megakaryocytes regulates thrombopoiesis

BACKGROUND

Platelet production is an intricate process that is poorly understood. Recently, we demonstrated that the natural peroxisome proliferator-activated receptor gamma (PPARgamma) ligand, 15-deoxy-Delta(12,14) prostaglandin J(2) (15d-PGJ(2)), augments platelet numbers by increasing platelet release from megakaryocytes through the induction of reactive oxygen species (ROS). 15d-PGJ(2) can exert effects independent of PPARgamma, such as increasing oxidative stress. Heme oxygenase-1 (HO-1) is a potent antioxidant and may influence platelet production.

OBJECTIVES

To further investigate the influence of 15d-PGJ(2) on megakaryocytes and to understand whether HO-1 plays a role in platelet production.

METHODS

Meg-01 cells (a primary megakaryoblastic cell line) and primary human megakaryocytes derived from cord blood were used to examine the effects of 15d-PGJ(2) on HO-1 expression in megakaryocytes and their daughter platelets. The role of HO-1 activity in thrombopoiesis was studied using established in vitro models of platelet production.

RESULTS AND CONCLUSIONS

15d-PGJ(2) potently induced HO-1 protein expression in Meg-01 cells and primary human megakaryocytes. The platelets produced from these megakaryocytes also expressed elevated levels of HO-1. 15d-PGJ(2)-induced HO-1 was independent of PPARgamma, but could be replicated using other electrophilic prostaglandins, suggesting that the electrophilic properties of 15d-PGJ(2) were important for HO-1 induction. Interestingly, inhibiting HO-1 activity enhanced ROS generation and augmented 15d-PGJ(2)-induced platelet production, which could be attenuated by antioxidants. These new data reveal that HO-1 negatively regulates thrombopoiesis by inhibiting ROS.

Video-assisted ductal ligation in premature infants

BACKGROUND

Video-assisted thoracic surgery has been shown to be a safe and effective method of closing the patent ductus arteriosus in infants and children. We have applied this technique in low birth weight premature infants and now report our experience.

METHODS

Since 1996, we have used video-assisted thoracic surgery ligation as the treatment of choice for all patent ductus arteriosus, including 100 performed on premature infants (23 to 31 weeks' gestation, mean 25.6 weeks; 0.420 to 1.5 kg, mean 0.859 kg). A modification of our previously described technique was used with a three-port approach. All patients had some degree of symptoms of congestive failure with failure to wean from ventilatory support or oxygen dependency. Five infants had associated patent foramen, and 1 had a small ventricular septal defect.

RESULTS

All 100 procedures were performed in the operating room. One infant was found to have a coarctation, and the procedure was aborted. The remaining 99 were successfully ligated, although three were converted to an open procedure (3%) because of coagulopathy, poor pulmonary compliance, or hemodynamic instability. There were no procedure-related deaths; however, 15 infants subsequently died of complications of prematurity, including enterocolitis, sepsis, and late respiratory failure. Six infants had chest tubes left in place for coagulopathy, effusions, suspected air leak, and existing empyema. There were six residual pneumothoraces, four requiring treatment.

CONCLUSIONS

Video-assisted thoracic surgery is a safe and effective technique for patent ductus arteriosus ligation in premature infants, including those with very low and extremely low birth weight.

The pharmacokinetics of epsilon-aminocaproic acid in children undergoing surgical repair of congenital heart defects

epsilon-Aminocaproic acid (epsilonACA) is often administered to children undergoing cardiac surgery by using empiric dosing techniques. We hypothesized that children would have different pharmacokinetic variables and require a dosing scheme different from adults to maintain stable and effective serum epsilonACA concentrations. Eight patients were enrolled in our study. epsilonACA 50 mg/kg was administered three times IV: before, during, and after cardiopulmonary bypass (CPB). Nine serum samples were obtained. epsilonACA plasma concentrations were measured by using high-performance liquid chromatography, and pharmacokinetic modeling was done by using NONMEM. The best fit was seen with a two-compartment model with volume of distribution (V(1)) adjusted for weight and CPB. Compared with published results in adults, modeling suggests that weight-adjusted V(1) is larger in children than in adults before, during, and after CPB. Clearance from the central compartment (k(10)) was also greater in children than adults, and declined during CPB. Redistribution rates from the central compartment, k(12) and k(21), were greater in children and not affected by CPB. We modeled several different dosing regimens for epsilonACA based on the larger V(1), and higher redistribution and clearance variables. We conclude that, because of the developmental differences in pharmacokinetic variables of epsilonACA, when compared with adult patients, a larger initial dose and faster infusion rate as well as an addi-tional dose on CPB are needed to maintain similar concentrations.

IMPLICATIONS

Pharmacokinetic modeling of epsilon-aminocaproic acid in children undergoing cardiac surgery suggests that there are developmental differences in pharmacokinetic variables. Based on these data, a dosing modification in children is suggested which may better maintain serum concentrations in children when compared with adults.

Rod pathways in the mammalian retina use connexin 36

Many neurons in the mammalian retina are coupled by means of gap junctions. Here, we show that, in rabbit retina, an antibody to connexin 36 heavily labels processes of AII amacrine cells, a critical interneuron in the rod pathway. Image analysis indicates that Cx36 is primarily located at dendritic crossings between overlapping AII amacrine cells. This finding suggests that Cx36 participates in homotypic gap junctions between pairs of AII amacrine cells. Cx36 was also found at AII/cone bipolar contacts, previously shown to be gap junction sites. This finding suggests that Cx36 participates at gap junctions that may be heterotypic. These results place an identified neuronal connexin in the context of a well-defined retinal circuit. The absence of Cx36 in many other neurons known to be coupled suggests the presence of additional unidentified connexins in mammalian neurons. Conversely, Cx36 labeling in other regions of the retina is not associated with AII amacrine cells, indicating some other cell types use Cx36.

Molecular Constants for the v=0, b(1)Sigma(g)(+) Excited State of O(2): Improved Values Derived from Measurements of the Oxygen A-Band Using Intracavity Laser Spectroscopy

High-resolution intracavity laser spectroscopy (ILS) absorption measurements have been made on the b-X oxygen electronic transition (the A-band) which has bandheads occurring in the region of 13 165 cm(-1). The positions of the lines were determined to an accuracy that is based on calibration with I(2) absorption lines using the Laboratoire Aimé Cotton (Orsay) Atlas as reference. Based on the ILS measurements and the more accurately determined positions given by L. R. Brown and C. Plymate (J. Mol. Spectrosc. 199, 166-179 (2000)) and with the (3)Sigma(g)(-) ground state molecular constants fixed at the values determined by G. Rouillé et al. (J. Mol. Spectrosc. 154, 372-382 (1992)), the following values (in cm(-1)) were found for the molecular constants: T(0)=13122.2524(1); B(0)=1.391244(2); D(0)=5.352(4)x10(-6); and H(0)=-1.2(2)x10(-11). These results are compared with values derived from fits of the line positions listed in several other studies of this transition. Copyright 2001 Academic Press.

Excitation--contraction uncoupling by a human central core disease mutation in the ryanodine receptor

Central core disease (CCD) is a human congenital myopathy characterized by fetal hypotonia and proximal muscle weakness that is linked to mutations in the gene encoding the type-1 ryanodine receptor (RyR1). CCD is thought to arise from Ca(2+)-induced damage stemming from mutant RyR1 proteins forming "leaky" sarcoplasmic reticulum (SR) Ca(2+) release channels. A novel mutation in the C-terminal region of RyR1 (I4898T) accounts for an unusually severe and highly penetrant form of CCD in humans [Lynch, P. J., Tong, J., Lehane, M., Mallet, A., Giblin, L., Heffron, J. J., Vaughan, P., Zafra, G., MacLennan, D. H. & McCarthy, T. V. (1999) Proc. Natl. Acad. Sci. USA 96, 4164--4169]. We expressed in skeletal myotubes derived from RyR1-knockout (dyspedic) mice the analogous mutation engineered into a rabbit RyR1 cDNA (I4897T). Here we show that homozygous expression of I4897T in dyspedic myotubes results in a complete uncoupling of sarcolemmal excitation from voltage-gated SR Ca(2+) release without significantly altering resting cytosolic Ca(2+) levels, SR Ca(2+) content, or RyR1-mediated enhancement of dihydropyridine receptor (DHPR) channel activity. Coexpression of both I4897T and wild-type RyR1 resulted in a 60% reduction in voltage-gated SR Ca(2+) release, again without altering resting cytosolic Ca(2+) levels, SR Ca(2+) content, or DHPR channel activity. These findings indicate that muscle weakness suffered by individuals possessing the I4898T mutation involves a functional uncoupling of sarcolemmal excitation from SR Ca(2+) release, rather than the expression of overactive or leaky SR Ca(2+) release channels.

Prevalence of infection in ticks submitted to the human tick test kit program of the U.S. Army Center for Health Promotion and Preventive Medicine

In 1997, ticks removed from humans and received alive by the Tick-Borne Disease Laboratory of the U.S. Army Center for Health Promotion and Preventive Medicine (USACHPPM) were tested for pathogens by polymerase chain reaction (PCR). Thirty-three of 222 (15%) Amblyomma americanum (L.) DNAs produced amplicons of the expected size of Ehrlichia chaffeensis Anderson, Dawson & Wilson and 26/222 (12%) produced amplicons indicating Borrelia burgdorferi Johnson, Schmid, Hyde, Steigalt & Brenner. Five (2%) appeared to be co-infected with both organisms. Thirteen of 308 (4%) Dermacentor variabilis (Say) were PCR-positive for spotted fever group rickettsiae. Restriction fragment-length polymorphism analysis indicated all were Rickettsia montana. One hundred twenty-seven D. variabilis from Monroe County, WI, were tested for B. burgdorferi and 14 (11%) were positive. Five of 24 (21%) Ixodes scapularis Say were positive for B. burgdorferi and one (2%) was positive for the agent of human granulocytic ehrlichiosis. Different species of ticks transmit different pathogens, and most tick-borne diseases have similar early symptoms, therefore knowing the species and infection status of the tick enhances the physician's ability to consider tick-borne agents as a potential cause of disease and recommend appropriate therapy. Ongoing surveillance of the vector species of human diseases provides an additional estimate of human encounters with infected ticks, and testing ticks removed from humans may increase our knowledge of the vector status of tick species for transmitting tick-borne pathogens.

Ehrlichia chaffeensis (Rickettsiales: Ehrlichieae) infection in Amblyomma americanum (Acari: Ixodidae) at Aberdeen Proving Ground, Maryland

Human monocytic ehrlichiosis (HME) is a sometimes fatal, emerging tick-borne disease caused by the bacterium Ehrlichia chaffeensis. It is frequently misdiagnosed because its symptoms mimic those of the flu. Current evidence indicates that Amblyomma americanum (L.), the lone star tick, is the major vector of HME. To determine if E. chaffeensis is present in ticks at Aberdeen Proving Ground, MD, questing A. americanum ticks were collected from 33 sites. Nucleic acid was extracted from 34 adult and 81 nymphal pools. Sequences diagnostic for E. chaffeensis from three different loci (16S rRNA, 120-kDa protein, and a variable-length polymerase chain reaction [PCR] target, or VLPT) were targeted for amplification by the PCR. Fifty-two percent of the collection sites yielded pools infected with E. chaffeensis, confirming the presence and widespread distribution of E. chaffeensis at Aberdeen Proving Ground. Analysis with the both the 120-kDa protein primers and the VLPT primers showed that genetic variance exists. A novel combination of variance for the two loci was detected in two tick pools. The pathogenic implications of genetic variation in E. chaffeensis are as yet unknown.

The Near-Infrared Transition of CuCl Observed by Intracavity Laser Spectroscopy

The near-infrared electronic transition of CuCl, occurring in the region of 745 nm, was recorded using intracavity laser absorption spectroscopy. The (0, 0), (1, 1), and (2, 2) vibronic bands were analyzed, and from this the molecular constants for the two electronic states were derived. Originally assigned as A' (3)Sigma(+)-X(1)Sigma(+), we have confirmed that this transition does not connect to the ground state, but occurs between two unknown excited states. The excited CuCl molecules were produced in a copper hollow cathode, operated using argon and a small amount of CCl(4). Line positions were referenced to iodine spectra observed from a heated extracavity cell using the broadband spectral output of the intracavity laser as the light source. Copyright 2000 Academic Press.

Histamine immunoreactive axons in the macaque retina

PURPOSE

The goal of these experiments was to identify the neurotransmitter in centrifugal axons of the macaque retina.

METHODS

Macaca mulatta retinas and optic nerves were fixed overnight in carbodiimide and labeled with an antiserum to histamine with the use of an immunofluorescence technique.

RESULTS

Several large histamine-immunoreactive axons ran from the optic nerve head to the peripheral retina, where they branched extensively and terminated in the inner plexiform layer, occasionally alongside retinal blood vessels. Other axons that emerged from the optic nerve head ran in the optic fiber layer to the central retina, circled the fovea, and then returned to the optic disc. These may be the source of histamine-immunoreactive axons that have been observed in central visual areas. No labeled cell bodies were present in the retina. Because perikarya in the posterior hypothalamus are the only known source of histamine in the primate central nervous system and because neurons there can be retrogradely labeled from the cut optic nerve, the histamine-immunoreactive axons must have originated there.

CONCLUSIONS

Centrifugal axons in the macaque retina are part of the system of axons containing histamine that originate in the hypothalamus and project throughout the brain. Because the activity of these neurons is highest during the morning, histamine might play a role in preparing the retina to operate in daylight. The contacts of histamine-immunoreactive axons with blood vessels suggest that histamine may also play a role in regulating the retinal microvasculature.

Overproduction of SM28GST in a baculovirus expression vector and its use to evaluate the in vivo immune responses of mice vaccinated against Schistosoma mansoni with naked DNA encoding the SM28GST gene

To evaluate the immune responses of mice vaccinated intramuscularly with naked DNA encoding a single parasite-derived gene, sufficient quantities of protein are necessary for use in the immunological assays. A plasmid carrying the cDNA encoding the entire sequence for the 28-kDa Schistosoma mansoni glutathione S-transferase (Sm28GST) was used as a source of naked DNA to vaccinate mice. Using polymerase chain reaction employing custom primers to add Eco RI and Hind III restriction sites at the 5' and 3' ends, respectively, a 651-bp fragment was amplified from the vaccine plasmid. This product was isolated, ligated into the pFastBac HTb donor plasmid containing a 6X histidine (6X-his) tag, and transposed into the baculovirus expression vector system. Following blue white selection screening, high molecular weight DNA was isolated and transfected in Sf21 insect ovary cells using a liposomal preparation. Culture medium containing infective virus particles was used to infect a series of Sf21 cultures and the cells were lysed after 3-5 days. The lysates were subjected to immobilized metal (Ni-NTA) affinity chromatography from which the 6X-his-tagged recombinant Sm28GST was eluted in 250 mM imidazole. The eluted protein was probed with a polyclonal rabbit antibody specific for the Sm28GST and subsequently recognized using a monoclonal antibody specific for the 6X-his tag following concentration of the pooled fractions. Mice were vaccinated intramuscularly with purified plasmid DNA encoding either the Sm28GST or firefly luciferase. Skin tests performed using recombinant Sm28GST were positive in only those mice vaccinated with naked DNA encoding the Sm28GST gene. In a different group of experimental mice, only sera from mice vaccinated with naked DNA encoding Sm28GST contained IgG-specific anti-Sm28GST antibodies at 14 days postvaccination, and at 42 days the levels were suggestive of an anamnestic response. These results suggest that naked DNA vaccination of mice is capable of inducing both antigen-specific cell-mediated and humoral immune responses against Sm28GST and further strengthen the case for this antigen being a vaccine candidate.

Cerebral emboli during cardiac surgery in children

BACKGROUND

Microemboli occur commonly during cardiac surgery in adults, and, when present, increase the risk of neuropsychological deficits. Their incidence and significance during correction of congenital heart disease is unknown. The authors hypothesized that microemboli would occur before bypass with right-to-left cardiac shunts and would also occur in large numbers when the aortic crossclamp was released in children during repair of congenital heart defects.

METHODS

In 25 children studied with carotid artery Doppler, embolic signals were counted and timed in relation to 13 intraoperative events. Patients were classified as either at high risk (obligate right-to-left shunt or uncorrected transposition of the great arteries) or at low risk (net left-to-right shunt or simple obstructive lesions) for paradoxical (venous to arterial) emboli.

RESULTS

The median number of emboli detected was 122 (range, 2-2,664). Forty-two percent of all emboli were detected within 3 min of release of the aortic crossclamp. The high-risk group had significantly more emboli (median, 66; range, 0-116) during the time interval before cardiopulmonary bypass than did the low-risk group (median, 8; range, 0-73), with P < 0.01. There was no significant difference between the high- and low-risk groups in the total number of emboli detected. There was no apparent association between number of emboli and gross neurologic deficits.

CONCLUSIONS

Microemboli can be detected in the carotid arteries of children undergoing repair of congenital heart disease and are especially prevalent immediately after release of the aortic crossclamp. The role of emboli in causing neurologic injury in children undergoing repair of congenital heart disease remains to be determined.

Intracavity laser absorption measurements at ultrahigh spectral resolution

Intracavity laser absorption spectroscopy with ultrahigh sensitivity and enhanced spectral resolution is demonstrated. It entails use of an intracavity étalon that selects equally spaced modes of the cavity. These modes are reduced in intensity when they occur at spectral locations where absorption that is due to intracavity species also occurs. We obtained absorption spectra by tuning the étalon in small steps across its free spectral range, recording intracavity spectra at each step, and summing the result. The maximum resolution is determined by the width of the étalon peaks, which was ~0.01 cm(-1). When the finesse of the étalon is increased, the resolution equal to the width of a single laser mode can be achieved. With this technique, spectra at Doppler-free resolution such as that required for studies of high vibrational-overtone transitions of molecules in supersonic jets are possible.

Pseudo-spectral methods and linear instabilities in reaction-diffusion fronts

We explore the application of a pseudo-spectral Fourier method to a set of reaction-diffusion equations and compare it with a second-order finite difference method. The prototype cubic autocatalytic reaction-diffusion model as discussed by Gray and Scott [Chem. Eng. Sci. 42, 307 (1987)] with a nonequilibrium constraint is adopted. In a spatial resolution study we find that the phase speeds of one-dimensional finite amplitude waves converge more rapidly for the spectral method than for the finite difference method. Furthermore, in two dimensions the symmetry preserving properties of the spectral method are shown to be superior to those of the finite difference method. In studies of plane/axisymmetric nonlinear waves a symmetry breaking linear instability is shown to occur and is one possible route for the formation of patterns from infinitesimal perturbations to finite amplitude waves in this set of reaction-diffusion equations. (c) 1996 American Institute of Physics.

Transesophageal echo probe compression of an aberrant right subclavian artery

Transesophageal echocardiography (TEE) is frequently used in the operating room to assess surgical repairs in children with congenital heart disease. Complications from the procedure are unusual, but the potential for TEE probe compression of normal and abnormal posterior vascular structures has been recognized. We report a case of TEE probe compression of an aberrant right subclavian artery in a patient undergoing repair of an atrioventricular septal defect.

An effective computer-based tardive dyskinesia monitoring system

To promote early recognition and treatment of neuroleptic-induced tardive dyskinesia we used our facility's pharmacy and appointment data bases to develop an automated reminder system that significantly improved physician monitoring of patients receiving antipsychotic drug therapy. The system prompts staff to perform regular examinations for abnormal involuntary movements and to review patients' consent to therapy with antipsychotic medication. The average prevalences in the 15 months after automated reminders began, in a population of over 800 patients, increased from 53% to 85% for an annually completed abnormal involuntary movement scale in medical records and from 38 to 74% for a statement of informed consent. Now, 45 months later, prevalences of both measures approaches 100%. The integrated design of the Department of Veterans Affairs computer system allowed linking pharmacy and appointment scheduling data and facilitated the project. The reminder system effectively promoted rapid, marked, and sustained change in physicians' documentation of antipsychotic drug therapy.

An in vitro comparison of biofilm formation on various biliary stent materials

Stent occlusion may occur as the result of bacterial adherence and biofilm formation. This occlusion may be prompted by the material or design of the stents. In this study, a bile perfusion model was used to compare the biofilm formation on various stent materials. The copolymer and the wire mesh stents demonstrated less biofilm formation than the traditional stent. The development of new polymers may prolong stent patency.