Thermodynamic Perspective on Field-Induced Behavior of α-RuCl_{3}

Measurements of the magnetic Grüneisen parameter (Γ_{B}) and specific heat on the Kitaev material candidate α-RuCl_{3} are used to access in-plane field and temperature dependence of the entropy up to 12 T and down to 1 K. No signatures corresponding to phase transitions are detected beyond the boundary of the magnetically ordered region, but only a shoulderlike anomaly in Γ_{B}, involving an entropy increment as small as 10^{-5}Rlog2. These observations put into question the presence of a phase transition between the purported quantum spin liquid and the field-polarized state of α-RuCl_{3}. We show theoretically that at low temperatures Γ_{B} is sensitive to crossings in the lowest excitations within gapped phases, and identify the measured shoulderlike anomaly as being of such origin. Exact diagonalization calculations demonstrate that the shoulderlike anomaly can be reproduced in extended Kitaev models that gain proximity to an additional phase at finite field without entering it. We discuss manifestations of this proximity in other measurements.

Riboflavin treatment of antiretroviral induced lactic acidosis and hepatic steatosis

BACKGROUND

Antiretroviral induced lactic acidosis and hepatic steatosis is a rare syndrome caused by inhibition of deoxyribonucleic acid (DNA) polymerase gamma by the Nucleoside Reverse Transcriptase Inhibitor (NRTI) class of antiretrovirals. There have been recent reports of NRTI-induced lactic acidosis treated with high-dose riboflavin.

INTERVENTION AND RESULTS

We report a case of NRTI lactic acidosis reversed with high-dose riboflavin. Treatment with 50 mg of riboflavin per day was initiated on hospital day 10 after the patient developed respiratory failure. Arterial lactate decreased from 11.9 mmol/dL to 2.1 mmol/dL. Despite lactic acidosis reversal the patient developed acute respiratory distress syndrome (ARDS) and expired. Autopsy confirmed extensive hepatic steatosis with no infectious agents identified.

CONCLUSION

Nucleoside Reverse Transcriptase Inhibitor lactic acidosis will likely become more prevalent with the trend toward aggressive antiretroviral treatment. This report provides additional support for the efficacy of riboflavin treatment to reverse this serious complication of antiretroviral therapy. Clinicians should have a high index of suspicion for lactic acidosis in a patient on NRTIs and the medications should be stopped at the earliest sign of toxicity.

Terminal nutrition: framing the debate for the withdrawal of nutritional support in terminally ill patients

Nutrition and hydration have long been considered to be life-sustaining therapies that are associated with comfort and relief of suffering. This belief is largely based on our own experiences with the sensations of thirst and hunger, which have led physicians to question whether withdrawing or withholding nutritional support from a dying patient can be morally or ethically justified. When considered in light of the available evidence, the underlying premise of this question must be reevaluated. The evidence suggests an alternative formulation, namely, that unrequested nutritional support provided by either the enteral or parenteral route to a terminally ill patient may be both medically and ethically indefensible because it may increase suffering without improving outcome.

Recessively inherited amyotrophic lateral sclerosis: a Germany family with the D90A CuZn-SOD mutation

Mutations of the SOD1 gene encoding the free radical scavenging enzyme copper-zinc superoxide dismutase (CuZn-SOD) occur in patients with familial amyotrophic lateral sclerosis (ALS). Recent reports have shown homozygosity for a CuZn-SOD mutation in exon 4, the D90A (Asp90A1a) mutation. Other mutations described to date show an autosomal dominant pattern of inheritance. This is the first description of autosomal recessively inherited ALS in an out-bred population in central Europe. This study confirms the earlier described characteristic phenotype reported in D90A homozygous ALS patients in Scandinavia and supports the theory of the existence of a strong modifying factor in some cases of ALS associated with mutations in the CuZn-SOD gene.

Hypoxemia after coronary bypass surgery modeled by resistance to oxygen diffusion

OBJECTIVE

To evaluate a model describing postoperative hypoxemia after cardiac surgery by using two variables, i.e., shunt and resistance to oxygen diffusion (Rdff).

DESIGN

Estimation of these two variables in normal subjects and postoperative cardiac patients.

SETTING

The pulmonary function laboratory for the normal subjects and the intensive care unit for the cardiac patients.

PATIENTS/SUBJECTS

Nine postoperative cardiac patients and six healthy subjects.

INTERVENTIONS

Inspired oxygen fraction was varied in normal subjects and in cardiac patients 3-6 hrs after surgery. This variation occurred in four to seven steps to achieve arterial oxygen saturations in the range 0.90-1.00.

MEASUREMENTS AND MAIN RESULTS

Measurements were taken of arterial oxygen saturation, cardiac output, ventilation, and end-tidal gases at each inspired oxygen fraction. These measurements gave the following estimates for the normal subjects: shunt = 3.9+/-5.4% (mean +/- SD) and Rdiff = -5+/-16 torr/(L/min) [-0.7+/-2.2 kPa/(L/min)]; for the cardiac patients: shunt = 7.7+/-1.8% and Rdiff = 212+/-230 torr/(L/min) [28.2+/-30.6 kPa/(L/min)]. The increase in Rdiff (P = .01) was sufficient to explain the observed hypoxemia in these patients. The value for shunt was not significantly increased in the patients (p = .09). The two-variable model (shunt and Rdff) gave a better prediction of arterial oxygen saturation than a model with shunt as the only variable (p = .02).

CONCLUSIONS

In cardiac patients requiring supplementary oxygen, the respiratory abnormality could, in our model, be best described by an increased Rdiff, not by an increased shunt value.

Synthesis and oral efficacy of a 4-(butylethylamino)pyrrolo[2,3-d]pyrimidine: a centrally active corticotropin-releasing factor1 receptor antagonist

The syntheses of a centrally active nonpeptide CRF1 receptor antagonist 2, butylethyl[2,5-dimethyl-7-(2,4,6-trimethylphenyl)-7H-pyrrolo [2,3-d]pyrimidin-4-yl]amine (CP-154,526), and its analogs 11-14 and [3H]-2 are reported. The in vitro CRF1 receptor binding affinity in the series 2, the pharmacokinetic properties of 2 in rats, and the anxiolytic-like effects of orally administered 2 are presented.

Clinical non-invasive measurement of effective pulmonary capillary blood flow

Since traditional pulmonary function testing is centered on measurements of air flow and lung volume, a method to assess the pulmonary circulation might improve our ability to evaluate diseases that impact upon pulmonary hemodynamics. We have developed a PC based application that rapidly calculates pulmonary blood flow. Subjects rebreath a mixture of 10% argon and 3.5% freon for 20 seconds. Gas concentrations at the mouth are monitored by a clinical mass spectrometer and signals are acquired and processed with off-the-shelf hardware. To test the accuracy and reproducibility of this technique, patients with pulmonary artery catheters were assessed by standard thermodilution methods and the rebreathing test. Measurements using this non-invasive technology closely corelate with invasive thermodilution methods (r = 0.980) and show equivalent reproducibility (average standard error = 2.5%). This application of signal processing technology can extend the role of pulmonary function testing to include routine evaluation of the pulmonary circulation.

Tissue distribution and elimination of indium in male Fischer 344 rats following oral and intratracheal administration of indium phosphide

The use of indium phosphide (InP) in the semiconductor industry has raised concerns about potential occupational exposure. The tissue distribution and elimination of indium were investigated in adult male Fischer 344 rats following either a single or 14 consecutive daily oral doses, or following an intratracheal instillation of InP (10 mg/kg). The concentrations of indium ions in blood, urine, feces, and tissues were quantified either using direct acid digestion followed by electrothermal atomic absorption spectrophotometry (ET-AAS) or using an extraction method with methyltricapryl ammonium ions to remove indium from the matrix followed by ET-AAS. Indium was poorly absorbed from the gastrointestinal tract in both single and multiple oral dose studies. Upon its absorption, indium was relatively evenly distributed among the major organs such as liver, kidney, lung, spleen, and testes. By 96 h after oral dose treatment, less than 0.11% of the dose of indium was recovered from tissues in the single- or multiple-dose experiment. At 96 h, retention of indium in the body was about 0.36% of the dose (except for lung) following intratracheal instillation of InP. Following oral dose administration, the majority of indium was recovered from the gastrointestinal tract and its contents. The high recovery of indium (73% of the dose) in the feces after intratracheal instillation presumably reflects mucociliary clearance and/or biliary excretion of indium. Urinary indium accounted only for 0.08-0.23% of the dose during a 240-h collection period in both single- and multiple-dose studies. It seems that fecal excretion serves as the major route for indium elimination, and this results from poor absorption. Because of the poor absorption of indium following multiple oral doses or intratracheal instillation of InP, it seems unlikely that indium will accumulate in the body following InP exposure.

Noninvasive estimation of pulmonary vascular resistance by stroke index measurement with an inert gas rebreathing technique

Patients with pulmonary hypertension (PH) have a cardiac limitation characterized by a decreased resting stroke index (SI) and an inability to augment stroke volume with exercise. We tested the hypothesis that a noninvasive estimation of SI, either at rest or with exercise, could be used to identify the presence and severity of PH. We used the inert gas rebreathing technique for measuring cardiac output and SI in nine subjects with PH and seven control subjects without pulmonary vascular disease. Noninvasive measurement of SI was compared with invasive measurement of pulmonary artery pressure (PAP), pulmonary vascular resistance index (PVRI), and SI. Inert gas estimation of cardiac output correlated well with invasive measurements (r = 0.94). All PH subjects had a depressed resting SI while all control subjects had a normal resting SI. An inverse correlation between the SI measured by inert gas technique and mean PAP was seen with both rest (r = 0.86) and exercise (r = 0.79). Because the resting SI differentiated subjects with PH from controls and correlated with disease severity, exercise measurements were not required. Multiple serial measurements performed in two PH subjects while receiving prostacyclin infusion produced a high level of correlation between the inert gas SI and mean pulmonary artery pressure. We conclude that inert gas measurement of SI may serve a useful role in the diagnosis and management of patients with PH.

Toxicokinetics of sulfasalazine (salicylazosulfapyridine) and its metabolites in B6C3F1 mice

The toxicokinetics of salicylazosulfapyridine (SASP) and its metabolites were investigated in male and female B6C3F1 mice either following single intravenous (5 mg/kg) or oral (67.5, 675, 1350, and 2700 mg/kg) doses, or following three consecutive daily oral doses (675, 1350, and 2700 mg/kg). Plasma concentrations of SASP and its metabolites were quantified by HPLC. Upon intravenous administration, SASP rapidly disappeared from blood with a mean residence time of 0.45-0.78 hr. The only metabolite of SASP found in plasma after an intravenous dose was sulfapyridine (SP). In both sexes, the absolute oral bioavailability of SASP ranged between 16.6-18.2% at a dose of 67.5 mg/kg, and between 2.6-8.7% at doses of 675-2700 mg/kg. Following oral administration of SASP, both SP and AcSP were identified in plasma. The area under the plasma concentration-time curves (AUC) of SP at all four oral doses were approximately 21- to 32-fold or 5- to 25-fold greater than those of SASP in male or female mice, respectively. The acetylated form of SP and AcSP, produced AUC values higher than SASP but much less than SP. Multiple oral doses with SASP did not alter the temporal patterns of SASP absorption and elimination in comparison to a single dose. However, SP accumulated in both sexes following multiple oral doses. A gender-dependent difference in toxicokinetic profiles for SASP and SP was also observed. Female mice displayed a higher Cmax of SASP and SP than did male mice. Although the volume of distribution of SASP was similar in both sexes, the systemic clearance of SASP in males was about twice that observed in females.(ABSTRACT TRUNCATED AT 250 WORDS)

The disposition of acrylic acid in the male Sprague-Dawley rat following oral or topical administration

The disposition of [1-14C] acrylic acid (AA) was characterized in the male Sprague-Dawley rat following oral administration, by gavage in water, at 400 mg/kg and topical application, in acetone, at 501 micrograms/cm2. The oral dose was well absorbed, rapidly and extensively metabolized, and excreted primarily (approx. 80%) as 14CO2 within 24 hr of administration. The rate and extent of 14CO2 evolution from [14C]AA was greater for [1-14CAA] while a significantly lower proportion of the dosed radioactivity remained in the tissue of animals than that reported for [2,3-14C]AA (Winter et al., Drug Metabolism and Disposition 1992, 20, 665). This is consistent with incorporation of AA into a minor beta-oxidation pathway of mitochondrial propionate metabolism by which AA may be metabolized to CO2 or incorporated into cellular constituents. Approximately 5% of the dosed radioactivity was excreted in the urine. The disposition of [1-14C]AA following dermal application was studied using charcoal-containing traps attached to the back of the rats to trap volatilized AA from the dosing sites. Following application of 100 microliters AA [4% (v/v) in acetone] to an area of 8.4 cm2 of the skin of a rat (501 micrograms/cm2), the majority (about 73%) of the dose volatilized and was recovered in the charcoal trap. Percutaneous absorption of AA that did not volatilize was rapid and appeared to have the same metabolic fate as AA administered orally with about 75% of the absorbed dose excreted as 14CO2 within 24 hr.

[Professional concept of physicians in child and adolescent psychiatry in former East Germany (1990)]

For this study the authors prepared a questionnaire for 662 child and youth psychiatrists with a return quota of 45%. Careerwise most medical doctors--working as psychiatrists and psychotherapists with an equal distribution in hospitals and offices--acquired further special training and education, particularly in Pediatrics, Psychotherapy and Autogenous Training. Work performance meets general agreement: a noticeable lack of corresponding doctors offices, mainly due to the economic situation. Unequivocal agreement exists concerning the necessity of diagnosis, the necessity of out-patient and in-patient therapy, as well the necessity of interdisciplinary cooperation. The views, however, on the quality of cooperation and the hierarchy within the team show differences. Views on self-concept almost equally determined an identification as doctor and as psychotherapist. The main professional motivations were enjoyment, success and ability. The professional concept was unvocally agreed upon. The survey revealed a poor reputation of child and adolescent psychiatrists. Professional basics include preserving the complexity in the field of child and adolescent psychiatry including medical assignments onesidedness rejected. Conflicts arise concerning the "professional self concept", resulting from the thin line between the required separation of child and adolescent psychiatry and associated professions and the required cooperation with associated professions.

Identification and comparison of the urinary metabolites of [1,2,3-13C3]acrylic acid and [1,2,3-13C3]propionic acid in the rat by homonuclear 13C nuclear magnetic resonance spectroscopy

Acrylic acid (AA) and its esters are used extensively for the production of a variety of polymers. Despite their ubiquitous nature, little has been reported on the metabolism of the parent acid. The metabolites of AA may be volatile, unstable, polar, and thus difficult to isolate. Therefore, 13C NMR was used to help identify and compare directly the urinary metabolites of both 99% 13C-enriched AA and propionic acid (PA). Male Sprague-Dawley rats received [1,2,3-13C]AA (400 mg/kg in water p.o.) or an equimolar dose of [1,2,3-13C]propionate together with a radioactive tracer, [2,3-14C]AA, or [1-14C]propionate, respectively, and excreta were collected for 72 hr. For both acids, expiration of 14CO2 was the major route of elimination of radiolabel (approximately 80%). Approximately 6% of the dose was excreted in the urine. Urine was analyzed directly using proton-decoupled 13C and two-dimensional 13C homonuclear correlated NMR spectroscopy. The urine from AA-treated rats revealed major signals, the intensity of which was time-dependent, from at least five 13C-enriched metabolites of AA. Signals have been assigned to 3-hydroxypropionic acid, N-acetyl-S-(2-carboxyethyl)cysteine, and N-acetyl-S-(2-carboxyethyl)cysteine-S-oxide by comparison with spectra of authentic standards. No unchanged AA was detected. In contrast, the spectra of urine from a propionate-treated rat revealed only a few minor 13C-enriched signals that were assigned to methylmalonic acid. No unchanged PA was detected.(ABSTRACT TRUNCATED AT 250 WORDS)

Stereoselective aliphatic hydroxylation of 6-n-propylchromone-2-carboxylic acid by female Dutch rabbits

6-n-Alkylchromone-2-carboxylic acids are metabolized solely by aliphatic oxidation. In the rabbit, the 6-n-propyl congener (PCCA) undergoes omega-1 hydroxylation exclusively. Following administration of PCCA to female Dutch rabbits (500 mumol/kg), some 77% of the dose was excreted in the urine, 41% as PCCA and 36% as 6-(2'-hydroxy-n-propyl)chromone-2-carboxylic acid. Since this metabolite is chiral, we have examined the stereochemistry of the excreted material. Diastereoisomeric (as camphanate and alpha-methoxy-alpha-(trifluoro-methyl)phenylacetate esters) and direct chiral HPLC and chiral lanthanide shift NMR have each shown the S:R ratio of the excreted metabolite to be 76:24. When rabbits were dosed with the racemic metabolite, excretion of the compound was not stereoselective. The regio- and stereo-selectivity of the aliphatic hydroxylation of PCCA are thus reflections of the selectivities of the enzyme systems responsible for its formation and suggest PCCA to be an appropriate probe compound for the study of prochiral-chiral hydroxylations.

Proteins of the respiratory tract after heart-lung transplantation

Heart-lung transplant recipients represent a unique population who experience episodic lung injury caused by infection or rejection. We hypothesized that the proteins in the respiratory lining fluids of these patients might reflect and provide insights into the in vivo immunologic and inflammatory events that occur in the transplanted lung. Structural, inflammatory, and immune proteins were quantitated in 57 samples of BAL fluid recovered from 17 heart-lung recipients when infections, rejection, or neither was present. Protein levels were compared with those of normal subjects and between the clinical transplant groups. When neither infection nor rejection was present, levels of albumin, fibronectin, and immunoglobulins G, M, and A were all higher in the transplanted lungs as compared with the normal lungs. These findings suggest that a new steady state of these proteins is established in the transplanted lungs. When infection or rejection was present, there was a further significant increase in albumin, fibronectin, IgG, and especially C5a in the transplanted lungs. These findings suggest that at least some elements of host defense remain intact in the posttransplantation period despite the use of immunosuppressive drugs and a HLA-incompatible microenvironment. The profiles of recovered alveolar proteins did not, however, help to differentiate infection from rejection. This is disappointing because distinguishing between infection and rejection without examination of lung tissue remains an unresolved and important clinical problem. Nevertheless these data provide new insights into organ tolerance and defense of the newly transplanted lung from infection or rejection.

Humoral response to disseminated infection by Mycobacterium avium-Mycobacterium intracellulare in acquired immunodeficiency syndrome and hairy cell leukemia

Antibody to Mycobacterium avium-Mycobacterium intracellulare antigen was measured by immunodiffusion, enzyme-linked immunosorbent assay (ELISA), and indirect immunofluorescence in sera from 30 patients with acquired immunodeficiency syndrome (AIDS), 10 patients with hairy cell leukemia, and 33 hospitalized and healthy controls. Ten patients with AIDS and three patients with hairy cell leukemia in the study population had disseminated M. avium-M. intracellulare infection. Patients with AIDS and disseminated infection had antimycobacterial antibody levels, demonstrated by ELISA, that did not differ significantly from those in uninfected patients with AIDS or controls. Infected patients with hairy cell leukemia had significantly higher levels of antimycobacterial antibody, demonstrated by ELISA, than did uninfected patients with hairy cell leukemia or controls (P less than .001). One patient with hairy cell leukemia, studied serially, showed a greater than 100-fold rise in antibody titer with the onset of infection. These results further demonstrate that AIDS involves a functional defect in humoral immunity, in addition to impairment of cellular immune function.

Calculation of viable and infarcted myocardial mass from thallium-201 tomograms

The feasibility of determining the mass of both viable and infarcted myocardium from tomographic images of thallium-201 distribution in the heart was studied in two normal dogs and ten dogs with acute infarction. Twenty-four hours after occlusion, thallium-201 was injected and 10 min later the hearts were removed and transaxial emission computed tomograms were obtained. Using the computer, an operator defined the epi- and endocardial surfaces of the left ventricle and the area of infarction in each tomogram. The computer then calculated values for total left-ventricular mass (TLVM) infarcted mass (IM) and the percentage of the left ventricle infarcted (% LVI). The calculated values were compared with measured weights, and good correlation was found between them: for TLVM, r = 0.87; for IM, r = 0.90; and for %LVI, r = 0.87. Good interobserver and intra-observer correlations were also found. Thallium-201 emission computed tomography offers a potential means to measure both myocardial mass and acute myocardial injury.