Excited-state quantum phase transitions in the anharmonic Lipkin-Meshkov-Glick model: Dynamical aspects

The standard Lipkin-Meshkov-Glick (LMG) model undergoes a second-order ground-state quantum phase transition (QPT) and an excited-state quantum phase transition (ESQPT). The inclusion of an anharmonic term in the LMG Hamiltonian gives rise to a second ESQPT that alters the static properties of the model [Gamito et al., Phys. Rev. E 106, 044125 (2022)2470-004510.1103/PhysRevE.106.044125]. In the present work, the dynamical implications associated to this new ESQPT are analyzed. For that purpose, a quantum quench protocol is defined on the system Hamiltonian that takes an initial state, usually the ground state, into a complex excited state that evolves on time. The impact of the new ESQPT on the time evolution of the survival probability and the local density of states after the quantum quench, as well as on the Loschmidt echoes and the microcanonical out-of-time-order correlator (OTOC) are discussed. The anharmonity-induced ESQPT, despite having a different physical origin, has dynamical consequences similar to those observed in the ESQPT already present in the standard LMG model.

Sutimlimab improves quality of life in patients with cold agglutinin disease: results of patient-reported outcomes from the CARDINAL study

Patients with cold agglutinin disease (CAD) experience fatigue and poor quality of life. However, previous CAD-related studies have not explored patient-reported outcomes such as the Functional Assessment of Chronic Illness Therapy (FACIT)-Fatigue. Sutimlimab, a C1s complement inhibitor, has been shown to halt haemolysis in CAD. Here, we present 26-weeks' patient-reported data from CARDINAL Part A (ClinicalTrials.gov, NCT03347396), which assessed efficacy and safety of sutimlimab in patients with CAD and recent history of transfusion. Aside from measuring changes in haemolytic markers, FACIT-Fatigue was measured at the treatment assessment timepoint (TAT; average of weeks 23, 25, and 26). Exploratory endpoints included the change in EuroQol 5-dimension 5-level questionnaire (EQ-5D-5L) and the 12-Item Short Form Health Survey (SF-12) at TAT, and Patient Global Impression of Change (PGIC), and Patient Global Impression of (fatigue) Severity (PGIS) at week 26. Mean (range) FACIT-Fatigue scores increased from 32.5 (14.0-47.0) at baseline (a score indicative of severe fatigue) to 44.3 (28.0-51.0) at TAT. Considerable improvements were reported for EQ-5D-5L at TAT, SF-12 scores at TAT, and PGIC and PGIS scores at week 26. Sutimlimab treatment resulted in sustained improvements in symptoms of fatigue and overall quality of life in patients with CAD. NCT03347396. Registered 20 November, 2017.

Excited-state quantum phase transitions in the anharmonic Lipkin-Meshkov-Glick model: Static aspects

The basic Lipkin-Meshkov-Glick model displays a second-order ground-state quantum phase transition and an excited-state quantum phase transition (ESQPT). The inclusion of an anharmonic term in the Hamiltonian implies a second ESQPT of a different nature. We characterize this ESQPT using the mean field limit of the model. The alternative ESQPT, associated with the changes in the boundary of the finite Hilbert space of the system, can be properly described using the order parameter of the ground-state quantum phase transition, the energy gap between adjacent states, the participation ratio, and the quantum fidelity susceptibility.

Complement-mediated hemolysis persists year round in patients with cold agglutinin disease

BACKGROUND

Cold agglutinin disease (CAD) is a rare autoimmune hemolytic anemia mediated by immunoglobulin M autoantibodies that bind to the "I" antigen on erythrocytes. IgM binding results in either agglutination at ≤37°C, activation of the classical complement pathway, or both. Patients with CAD can have transient agglutination-mediated circulatory symptoms triggered by exposure to cold conditions. Separately, patients with CAD can experience complement-mediated symptoms such as anemia, hemolysis, and fatigue, but the effect of the season on these complement-mediated manifestations of CAD and clinical outcomes is not well understood.

METHODS

Using data from the Optum® de-identified Electronic Health Record dataset, we compared hemoglobin, markers of hemolysis (bilirubin and lactate dehydrogenase [LDH]), and healthcare resource utilization (HRU) between seasons for 594 patients (62% female; 66% aged ≥65 years) with CAD (defined as having CAD-related terms in their clinical notes on ≥3 separate occasions between December 2008 and May 2016). Laboratory parameters and HRU were compared between seasons using multivariate regression models.

RESULTS

Estimated median hemoglobin (9.87 g/dL in summer and 9.86 g/dL in winter; P = 0.944) and bilirubin (1.04 mg/dL in summer and 1.09 mg/dL in winter; P = 0.257) were similar in winter versus summer. While LDH was statistically significantly higher in winter compared with summer (P < 0.001), the estimated median value was above normal for both seasons (309 U/L in summer and 367 U/L in winter). HRU measures and transfusion and thromboembolism rates were similar across seasons.

CONCLUSIONS

Patients with CAD had evidence of persistent chronic hemolysis, HRU, and thromboembolism risk year round.

Healthcare resource utilization among commercially insured patients with cold agglutinin disease in the United States

Aims: Cold agglutinin disease (CAD) is a rare subtype of autoimmune hemolytic anemia associated with increased thromboembolism risk and early mortality. Healthcare resource utilization (HRU) in CAD has not been reported. We aimed to compare HRU of patients with CAD with a matched non-CAD cohort in the United States.Materials and methods: Patients with CAD were identified from 2006 to 2016 in the Optum-Humedica database using CAD terms in clinical notes and hematologist review. Patients were required to have Integrated Delivery Network records and ≥6 months' follow-up before and after the first CAD mention date (index date). Patients with CAD were matched to a non-CAD cohort based on demographics. Multivariate analyses assessed inpatient hospitalizations, outpatient visits, emergency room visits, and transfusion use between cohorts 6 months before and 12 months after the index date.Results: Of 814 patients with CAD, 410 met inclusion criteria and were matched to 3,390 patients without CAD. Mean age of patients with CAD was 68.0 years; approximately 62% were female. In the 12 months after the index date, mean inpatient hospitalizations (0.83 vs. 0.25), outpatient visits (17.26 vs. 6.77), emergency room visits (0.55 vs. 0.32), and transfusion days (1.05 vs. 0.05) were higher for patients with CAD than the matched non-CAD cohort (all p < .0001). Similarly, in the 6 months before the index date, patients with CAD had higher HRU than matched patients without CAD for all measures evaluated.Limitations: Results of this study are based on patient information from the Optum-Humedica database, which is limited to commercially insured patients and may not represent the overall CAD population.Conclusions: CAD places a substantial burden on patients and healthcare systems. In addition, the high HRU for patients with CAD observed in the 6 months before diagnosis indicates that disease awareness and better diagnostic practices may be needed.

Quantum phase transitions of atom-molecule Bose mixtures in a double-well potential

The ground state and spectral properties of Bose gases in double-well potentials are studied in two different scenarios: (i) an interacting atomic Bose gas, and (ii) a mixture of an atomic gas interacting with diatomic molecules. A ground state second-order quantum phase transition is observed in both scenarios. For large attractive values of the atom-atom interaction, the ground state is degenerate. For repulsive and small attractive interaction, the ground state is not degenerate and is well approximated by a boson coherent state. Both systems depict an excited state quantum phase transition. In both cases, a critical energy separates a region in which all the energy levels are degenerate in pairs, from another region in which there are no degeneracies. For the atomic system, the critical point displays a singularity in the density of states, whereas this behavior is largely smoothed for the mixed atom-molecule system.

Excited-state phase transition and onset of chaos in quantum optical models

We study the critical behavior of excited states and its relation to order and chaos in the Jaynes-Cummings and Dicke models of quantum optics. We show that both models exhibit a chain of excited-state quantum phase transitions demarcating the upper edge of the superradiant phase. For the Dicke model, the signatures of criticality in excited states are blurred by the onset of quantum chaos. We show that the emergence of quantum chaos is caused by the precursors of the excited-state quantum phase transition.

Critical-point symmetries in boson-fermion systems: the case of shape transitions in odd nuclei in a multiorbit model

We investigate phase transitions in boson-fermion systems. We propose an analytically solvable model [E(5/12)] to describe odd nuclei at the critical point in the transition from the spherical to gamma-unstable behavior. In the model, a boson core described within the Bohr Hamiltonian interacts with an unpaired particle assumed to be moving in the three single-particle orbitals j=1/2, 3/2, 5/2. Energy spectra and electromagnetic transitions at the critical point compare well with the results obtained within the interacting boson-fermion model, with a boson-fermion Hamiltonian that describes the same physical situation.

Phase diagram of the proton-neutron interacting boson model

We study the phase diagram of the proton-neutron interacting boson model with special emphasis on the phase transitions leading to triaxial phases. The existence of a new critical point between spherical and triaxial shapes is reported.

Quantum phase transitions in the interacting boson model: integrability, level repulsion, and level crossing

We study the quantum phase transition mechanisms that arise in the interacting boson model. We show that the second-order nature of the phase transition from U(5) to O(6) may be attributed to quantum integrability, whereas all the first-order phase transitions of the model are due to level repulsion with one singular point of level crossing. We propose a model Hamiltonian with a true first-order phase transition for finite systems due to level crossings.

Lanthanum fixation by Myxococcus xanthus: cellular location and extracellular polysaccharide observation

Myxococcus xanthus is a soil bacterium of the myxobacteria group and is abundant in almost all soils. Its role in soil ecology is considered significant. One noteworthy characteristic of the bacterium is that it produces large quantities of extracellular polymeric substances (EPS). It is also known that its biomass has the capacity to fix heavy metals. Here it is reported that M. xanthus was able to accumulate 0.6 mmol of La per g of wet biomass and/or 0.99 mmol per g of dry biomass. Transmission Electron Microscopy (TEM) observation of M. xanthus cells treated with La showed that a substantial amount of this cation was fixed in the EPS and in the cell wall. Smaller amounts were also observed in the cytoplasm. Fixed La appeared as phosphate in all cellular locations. The results given here also show that the use of La enables TEM observation of the M. xanthus EPS as a dense fibrillar net surrounding the cells. This technique is relatively easy and prevents EPS collapse, which occurs frequently during the fixation and dehydration procedures commonly used in preparations for TEM observations. Since antibodies are no longer required, the La stain can be carried out without delaying bacterial cell cultivation or isolation. In addition, the presence of La in cell cytoplasm without cell degeneration suggests that this microorganism could be used as a model in the study of bacteria-lanthanide interactions.

mlpB, a gene encoding a new lipoprotein in Myxococcus xanthus

AIMS

To search for and study the genes involved in the regulation of phosphate in the soil developmental bacterium Myxococcus xanthus.

METHODS AND RESULTS

The mlpB gene encoding a 149 residue polypeptide was identified while screening for genes with products related to phosphate metabolism. The amino terminal 19 residues of MlpB encode a typical prokaryotic signal sequence with a putative lipoprotein cleavage site.

CONCLUSIONS

In this study, a new myxobacterial putative lipoprotein is reported. The data suggest that MlpB may be involved in the secretion of phosphate-related proteins.

SIGNIFICANCE AND IMPACT OF THE STUDY

Soil bacteria have complex regulatory systems for using inorganic phosphate. This nutrient is limiting in the environment, and has a critical importance for growth and in the initiation of differentiation for developmental bacteria. A number of proteins are involved in all these processes, including membrane lipoproteins, which are being increasingly studied in M. xanthus.

Myxococcus xanthus biomass as biosorbent for lead

This paper deals with lead biosorption by Myxococcus xanthus biomass in which dry biomass, accumulating up to 1.28 mmol of lead g(-1), is demonstrated to be a more efficient biosorbent than wet biomass. Dry biomass biosorption was found to be very rapid, reaching equilibrium after 5-10 min. Culture age, the initial lead concentration and pH affected this process, but temperature did not. Furthermore, by using sodium citrate as a desorbent agent, 92.17% of the biosorbed lead could be recovered. It was also established that the biosorbed lead is located on the cellular wall and within the characteristic extracellular polysaccharide of this micro-organism.

Biotransformation of 4beta-hydroxyeudesmane-1,6-dione by Gliocladium roseum and Exserohilum halodes

Biotransformation of sesquiterpene 4beta-hydroxyeudesmane-1,6-dione by the filamentous fungi Gliocladium roseum and Exserohilum halodes was achieved. With Exserohilum halodes, only one metabolite was obtained, as a result of the regio- and stereoselective reduction of the keto group at C-1, which is difficult to achieve by chemical means. Five metabolites were produced with Gliocladium roseum, three of which, the 7alpha-hydroxylated, the 7alpha,11- and the 1alpha,8alpha-dihydroxylated derivatives, have not previously been reported. The hydroxylation at C-11 is the main action of this microorganism. These 11-hydroxylated compounds can be chemically transformed into 6beta,12-eudesmanolides.

Glycerol 3-phosphate inhibits swarming and aggregation of Myxococcus xanthus

We have cloned a gene of Myxococcus xanthus with similarities to the permease for glycerol 3-phosphate (G3P) of other bacteria. Expression of the gene increased significantly during the first hours of starvation. Swarming of the wild-type strain was inhibited and aggregation was delayed by G3P. Conversely, a DeltaglpT strain aggregated even on rich medium. These results indicate that G3P may function to regulate the timing of aggregation in M. xanthus.

Regioselective enzymatic acylations of polyhydroxylated eudesmanes: semisynthesis, theoretical calculations, and biotransformation of cyclic sulfites

Different lipase enzymes have been tested in order to perform regioselective acetylations on the eudesmane tetrol from vulgarin. High yields (95%) of 1,12-diacetoxy derivative (4) were achieved in 1 h with Candida antarctica lipase (CAL). However, only the 12-acetyl derivative (6) was obtained in similar yield with Mucor miehei (MML) or Candida cylindracea (CCL) lipases. The enzymatic protection at C-1 and C-12 has been used to form eudesmane cyclic-sulfites between C-6 and C-4 atoms. The R/S-sulfur configuration has been assigned by means of the experimental and theoretical (13)C and (1)H NMR chemical shifts. The theoretical shifts were calculated using the GIAO method, with a MM+ geometry optimization followed by a single-point calculation at the B3LYP/6-31G(*) level (B3LYP/6-31G(*)//MM+). Moreover, B3LYP/6-31G(*) geometry optimizations were carried out to test the B3LYP/6-31G(*)//MM+ results, for the deacetylated sulfites (12 and 15). In addition to the delta(C) and delta(H) shifts, the (3)J(HH) coupling constants were also calculated and compared with the experimental values when available. Finally, different reactivities have been checked in both sulfites by biotransformation with Rhizopus nigricans. While the R-sulfite gave 2 alpha- and 11 beta-hydroxylated metabolites, the S-sulfite yielded only regioselective deacetylations. Furthermore, both sulfites showed different reactivities in redox processes.

Activation of a Ca2+-permeable cation channel by two different inducers of apoptosis in a human prostatic cancer cell line

1. We have combined patch clamp recording with simultaneous [Ca2+]i measurements in single LNCaP cells (a human prostate cancer cell line), to study the activation of Ca2+-permeable channels by two different inducers of apoptosis, ionomycin and serum deprivation. 2. In perforated patch recording, LNCaP cells had a membrane potential of -40 mV and a resting [Ca2+]i of 90 nM. Application of ionomycin at levels that induced apoptosis in these cells (10 microM) produced a biphasic increase in [Ca2+]i. The first rise in [Ca2+]i was due to release of Ca2+ from internal stores and it was associated with a membrane hyperpolarization to -77 mV. The latter was probably due to the activation of high conductance, Ca2+- and voltage-dependent K+ channels (maxi-K). Conversely, the second rise in [Ca2+]i was always preceded by and strictly associated with membrane depolarization and required external Ca2+. Serum deprivation, another inducer of apoptosis, unmasked a voltage-independent Ca2+ permeability as well. 3. A lower concentration of ionomycin (1 microM) did not induce apoptosis, and neither depolarized LNCaP cells nor produced the biphasic increase in [Ca2+]i. However, the first increment in [Ca2+]i due to release from internal Ca2+ stores was evident at this concentration of ionomycin. 4. Simultaneous recordings of [Ca2+]i and ion channel activity in the cell attached configuration of patch clamp revealed a Ca2+-permeable, Ca2+-independent, non-selective cation channel of 23 pS conductance. This channel was activated only during the second increment in [Ca2+]i induced by ionomycin. The absence of serum activated the 23 pS channel as well, albeit at a lower frequency than with ionomycin. 5. Thus, the 23 pS channel can be activated by two unrelated inducers of apoptosis and it could be another Ca2+ influx mechanism in programmed cell death of LNCaP cells.

Sex differences and age-related changes in human serum aminopeptidase A activity

Given that aminopeptidase A is primarily responsible for cleaving aspartic acid and converting angiotensin II to angiotensin III, the purpose of the present study was to evaluate the activity of aminopeptidase A by determination of glutamate aminopeptidase activity (GluAP) and aspartate aminopeptidase activity (AspAP) (reported respectively as aminopeptidase A and angiotensinase A activities) in human serum during development and ageing, in an apparently healthy population of 139 male and 148 female subjects. To measure GluAP and AspAP we used glutamyl- and aspartyl-2-naphthylamide as substrates. Significant age-related increases were observed in GluAP activity in males and females and in AspAP activity in females. In males, there were no age-related differences in AspAP activity. A significant correlation was observed between age and GluAP activity in the population analysed as a whole or according to sex. No correlation was demonstrated between age and AspAP activity either in the whole population or according to sex. These results may reflect the evolution of the functional status of susceptible circulating substrates during development and ageing.

Extracellular bacterial mineralization within the context of geomicrobiology

In the biosphere, bacteria can function as geochemical agents, promoting the dispersion, fractionation and/or concentration of matter. These processes, which are being more and more valued from the point of view of various scientific disciplines, have given rise to the field of geomicrobiology. At the same time, microbial processes resulting in the concentration of matter and thus inducing the formation of minerals, constitute an area of research of growing interest known as biomineralization. In this review a succinct summary of various aspects of both disciplines has been offered together with a more detailed review of those aspects related to extracellular bacterial mineralization. The significance of the role played by the metabolism of bacteria is discussed along with the results of recent research on the role of dead bacteria and bacterial remains that act as heterogeneous nuclei of crystallization. The role played by the membranes of bacteria has also been considered to be highly relevant, and a discussion concerning their possible value as models for both the study of more complex biomineralization processes as well as application in the field of biomimetic materials is put forward.

Determination of glomerular filtration rate using technetium-99m-DTPA with differing degrees of renal function

Glomerular filtration rate (GFR) is an important index of renal function. Twenty-four-hour creatinine clearance overestimates GFR in patients with poor renal function. Inulin and iothalamate clearances are accepted reference standards for determining GFR but are expensive and laborious. We have previously reported that GFRs obtained by measuring the disappearance of 99mTc-DTPA from ultrafiltered (protein-free) samples of plasma were virtually identical to those obtained by the iothalamate method. However, the subjects used in that study had normal to only moderately decreased renal function.

METHODS

The accuracy of measuring GFR by plasma clearance of 99mTc-DTPA was determined in subjects where renal function varied from normal to severely impaired. In all subjects, GFR was established by clearance of 125I-iothalamate from urine and serum and was used as the standard of reference.

RESULTS

For subjects with normal to moderately diminished renal function (GFR > 20 ml/min), the correlation between values of GFR obtained by the DTPA and iothalamate methods was high (n = 18, r = 0.966). The difference between the pairs of GFR values obtained by the two methods was not statistically significant (p > 0.1). In patients with severe renal insufficiency (GFR < 20 ml/min), the correlation between the DTPA and iothalamate methods was poor (n = 11, r = 0.236), and the GFR values obtained by the two methods were statistically different (p < 0.01).

CONCLUSION

These results suggest that GFR can be determined accurately by plasma clearance of 99mTc-DTPA in all patients except those with severe renal insufficiency.

Progressive posttraumatic myelomalacic myelopathy: treatment with untethering and expansive duraplasty

Patients with progressive posttraumatic myelomalacic myelopathy (PPMM), or tethered cord syndrome, present with symptoms and signs similar to those observed in case of progressive posttraumatic cystic myelopathy, that is, sensorimotor function deterioration, local and/or radicular pain, increased spasticity, increased autonomic dysreflexia, and sphincter dysfunction. The authors investigated surgical outcomes of untethering combined with expansive duraplasty. Forty patients with PPMM who presented with functional deterioration underwent untethering of the spinal cord and nerve roots with an expansive duraplasty. Meticulous dissections of adhesions on the dorsal and lateral aspects of the spinal cord and nerve roots were performed. Intraoperative ultrasonography was used to detect the presence of a confluent cyst and to assess the success of untethering. After surgery, the patients were treated using a protocol that involved frequent turning for 48 hours and subsequently mobilization. Preoperative magnetic resonance (MR) imaging, with and without administration of a contrast agent, was obtained in all patients, except one patient who underwent immediate and delayed computerized tomography (CT) myelography. The mean follow-up period was 3 years (range 20-57 months) for the 36 patients available for follow-up review. Spinal cord tethering was observed in all patients preoperatively. Trauma was the most common cause of this pathology, accounting for 31 of the 40 cases. Preoperative MR imaging did not demonstrate tumor recurrence in the group of five patients who had undergone an initial operation for tumor excision. The interval between the causative event and the operation was less than 5 years in half of the patients (20 of 40), with the longest interval lasting up to 37 years. Motor function deterioration was the most frequent manifestation; it was present in 31 of 40 patients. Improvements in motor function, autonomic dysreflexia, pain, sphincter dysfunction, and sensory function were found during the most recent follow-up examination in 79%, 75%, 62%, 50%, and 43% of the patients, respectively. Two patients experienced retethering of the spinal cord and one underwent a second operation. Surgical untethering and expansive duraplasty, followed by postoperative position rotation to avoid retethering, provide symptomatic relief for patients with PPMM.

Brewery yeast as a biosorbent for uranium

Yeast cells are capable of carrying out biosorption with various heavy metals. The biomass deriving from Saccharomyces cerevisiae coming from brewing industries is a by-product that is possible to be used in the purification of water contaminated with these ions. In this paper we show that yeast biomass from one of the city's breweries can adsorb uranium efficiently, up to 2.4 mmol of this metal per gram of dry biomass. It can also be seen that the temperature (between 10 degrees and 37 degrees C) has no effect on the biosorption, while pH does have an influence, 4.5 being the best value. When the concentrations of uranium range between 0.1 and 0.5 mol l-1 the yeast dry biomass is capable of adsorbing between 84% and 98% of this metal in solution.

The social behavior of myxobacteria

Myxobacteria are social microorganisms that undergo a spectacular cell cycle. Under starvation conditions, cells aggregate to certain points originating macroscopic fruiting bodies, inside which cells differentiate into myxospores. To accomplish this developmental cycle, cells must communicate. The signals that cells exchange during development as well as the signal transduction systems used by myxobacteria have been intensively studied during the last years. A family of eukaryotic-like protein serine/threonine kinases has been identified in Myxococcus xanthus, indicating that signal transduction systems similar to those used by eukaryotic cells may also function in myxobacteria.

New polyoxygenated ent-manoyl oxides obtained by biotransformation with filamentous fungi

Incubation of methyl (13R)-ent-16-hydroxy-8 alpha,13-epoxylabd-14-en-18-oate [4] with Curvularia lunata yielded ent-1 beta-hydroxy [6] and ent-6 beta-hydroxy [7] derivatives, and that of methyl (13S)-ent-16-dihydroxy-8 alpha,13-epoxylabd-14-en-18-oate [5] with the same organism gave ent-11 beta-hydroxy [8], ent-6 beta-hydroxy [9], and ent-6 beta,11 beta-dihydroxy [10] derivatives. The incubation of substrates 4 and 5 with Fusarium moniliforme afforded ent-1 beta-hydroxy derivatives (6 and 14, respectively). Cunninghamella elegans produced ent-3 beta-hydroxy, ent-1 beta-hydroxy and ent-1 beta,3 beta-dihydroxy derivatives, and led to epoxidation of the double bond of the substrates. In addition, ent-3 beta,11 alpha-dihydroxy (as the acetoxy derivative 17) and ent-3 beta,11 beta-dihydroxy [12] derivatives were isolated from incubations of substrates 4 and 5, respectively. Compounds 7, 9-11, 14, 16-18, and 21 were characterized as new polyoxygenated ent-manoyl oxides.

Synthesis of enantio-manoyl oxides: modifiers of the activity of adenylatecyclase enzyme

Cyclization of methyl ent-8 alpha-hydroxylabd-13(16),14-dien-18-oate with m-chloroperbenzoic acid gave methyl (13S)-ent-16-hydroxy-8 alpha,13-epoxylabd-14-en-18-oate and its epimer at C-13. Biotransformation of the former (which exhibits antileishmania activity) with Rhizopus nigricans cultures produced the methyl (13S)-ent-11 beta,16-dihydroxy-8 alpha,13-epoxilabd-14-en-18-oate (carbomanoyl, which inhibits the activity of the adenylatecyclase enzyme), methyl (13S)-ent-3 beta,16-dihydroxy-8 alpha,13-epoxilabd-14-en-18-oate, methyl (13S)-ent-3 beta,11 beta,16-trihydroxy-8 alpha,13-epoxilabd-14-en-18-oate and the (14S)-ent-3 beta-hydroxy-14,15-epoxy derivative that cyclized spontaneously to a spiran compound. Biotransformation of methyl (13S)-ent-16-hydroxy-3-oxo-8 alpha,13-epoxilabd-14-en-18-oate with R. nigricans produced ent-11 beta-hydroxylation, reduction of the keto group at C-3 (to give 3S-alcohol) and 14(S),15-epoxidation, which also rearranged to a spiro compound.

Autolytic effect of the antibiotic produced by Myxococcus coralloides D

Myxococcus coralloides D secretes an antibiotic, named corallolysin, when grown on a rich medium. When a critical concentration is reached, this antibiotic lyses the producer bacterium either during vegetative growth or during morphogenesis. Corallolysin has not effect on resting cells nor on myxospores. The autolytic effect is caused by the early inhibition of RNA synthesis.

Chemical-microbiological synthesis of ent-13-epi-manoyl oxides with biological activities

The biotransformation of ent-13-epi-3-keto manoyl oxide, which possesses antileishmania activity, with Curvularia lunata produced ent-6 beta-hydroxy, ent-1 alpha-hydroxy, ent-11 beta-hydroxy and delta 1-derivatives, as well as a reduction product a C-3 (S-alcohol) with another hydroxyl group at C-6 (ent-6 beta) or C-11 (ent-11 beta). The ent-6 beta-hydroxy and delta 1-derivatives inhibited growth of the pathogenic protozoa, Leishmania donovani. The biotransformation of ent-12 alpha-acetoxy-3 beta-hydroxy-13-epi-manoyl oxide and ent-3 beta-acetoxy-12 beta-dihydroxy-13-epi-manoyl oxide gave ent-3 eta,12 beta-dihydroxy-13-epi-manoyl oxide and ent-3 beta,6 beta,12 beta-trihydroxy-13-epi-manoyl oxide (trimanoyl). Both products increased the activity of adenylatecyclase.

Comparison of methods for identifying early methotrexate-induced hepatotoxicity in patients with rheumatoid arthritis

Hepatotoxicity may complicate therapy with methotrexate in patients with rheumatoid arthritis. Prevention of cirrhosis may depend upon early identification of liver damage, usually accomplished by serial biopsy. To determine the adequacy of noninvasive methods for identifying hepatotoxicity, 22 sets of data were obtained in patients undergoing therapy with methotrexate for rheumatoid arthritis. Comparisons were made between liver biopsy, hepatocellular enzymes and two noninvasive radioisotopic methods that have been shown to be abnormal in hepatocellular disease: the rate constant of excretion of the 14C-aminopyrine and the time from injection to peak hepatic activity of 99mTc-diisopropylimidodiacetic acid. The hepatocellular enzymes and the time-to-peak-activity of diisopropylimidodiacetic acid were not useful predictors of methotrexate-induced hepatotoxicity. The aminopyrine breath test was abnormal in approximately half the patients with hepatotoxicity but showed poor specificity. Noninvasive methods remain inferior to biopsy for the detection of mild to moderate methotrexate-induced hepatotoxicity in patients with rheumatoid arthritis.

Repair of facial nerve after removal of cerebellopontine angle tumors: a comparative study

The results of repair of 18 facial nerves were examined by means of a modified House-Brackmann grading system. Six were repaired by end-to-end anastomosis and 12 by nerve graft. The reliability of the simplified House-Brackmann grading system was also assessed, using the kappa statistic to analyze the agreement between pairs of observers who examined the function of 40 nerves in 37 patients. Facial nerves studied had been either preserved, repaired or grafted, or divided and treated by faciohypoglossal nerve anastomosis. One nerve was not treated. The grading system proved to be somewhat unreliable, with complete agreement between observers in only 25% of cases. Facial nerve repair produced a fair return of function in just under two-thirds of the cases. The ability of an examiner ignorant of the patient's history to assess from the end result how the nerve had been managed was also estimated. Observers showed little ability to decide correctly on the previous treatment of the nerve when the patient showed moderate dysfunction postoperatively. The implications of these findings for grading systems and for management of the facial nerve in acoustic nerve tumor surgery are discussed.

Deoxyribonuclease activities in Myxococcus coralloides D

Myxococcus coralloides D produced cell-bound deoxyribonucleases (DNases) during the exponential phase of growth in liquid medium. DNase activity was much higher than that detected in other myxobacterial strains and was fractionated into three different peaks by filtration through Sephadex G-200. The DNases were named G, M and P. The optimum temperatures were 37 degrees C, 33 degrees C and 25 degrees C respectively, although high activities were recorded over the temperature range 20-45 degrees C. The pH range of high activity was between 6.0 and 9.0, with an optimum for each DNase at 8.0. DNases M and P were strongly inhibited by low concentrations of NaCl, but activity of DNase G was less affected by NaCl. The three activities required divalent metal ions as cofactors (especially Mg2+ and Mn2+); however, other metal ions (Fe2+, Ni2+, Zn2+) were inhibitors. The molecular weights were estimated by gel filtration chromatography and SDS-PAGE as 44 kDa (DNase G), 49 kDa (DNase M) and 39 kDa (DNase P).

Naloxone reverses pattern of obstruction of the distal common bile duct induced by analgesic narcotics in hepatobiliary imaging

It is widely known that narcotics, such as morphine, cause spasm of the sphincter of Oddi, increasing pressure in the common bile duct. This pharmacologic effect has been applied to hepatobiliary scintigraphy in patients with chronic cholecystitis or cholestasis to reducing the time required for a diagnostic study. However, this feature of narcotics could result in delayed or nonvisualization of the small bowel, simulating a distal common bile duct obstruction, in patients requiring parenteral narcotic analgesics who must undergo hepatobiliary scintigraphy. We report on three patients where administration of intravenous naloxone hydrochloride (Narcan), a narcotic antagonist, was helpful in distinguishing narcotic-induced spasm of the sphincter of Oddi from true obstruction of the common bile duct.

Effect of phosphate on antibiotic and extracellular protein production by Myxococcus coralloides D

The effect of inorganic phosphate concentrations on antibiotic and extracellular protein production by Myxococcus coralloides D have been examined. Antibiotic production by growing cells of this myxobacterium was maximal at phosphate concentrations of 10-20 mM, but was inhibited by concentrations higher than 20 mM. The total extracellular protein and the extracellular protein per cell ratio were independent of phosphate levels in the culture broth.

Production of acid and alkaline phosphatases by Myxococcus coralloides

Acid and alkaline phosphatase of Myxococcus coralloides were examined during vegetative growth in a liquid medium. Two extracellular phosphatases and two cell-bound phosphatases, acid and alkaline in both cases, were produced. The phosphatase production was unaltered by the presence of high concentrations of inorganic phosphate. Both enzymes were produced constitutively. These two hydrolases were released into the growth medium during the exponential growth phase (approximately 10% of total activity). The production of these enzymes was modified by the presence of organic acids and metal ions in the medium.

Production and properties of a bacteriocin from Myxococcus coralloides D

Myxococcus coralloides D was found to produce a substance with a narrow range of antibacterial activity. This substance was produced during the exponential growth phase and was not inducible by ultraviolet light or mitomycin C treatment. The bacteriocin was precipitable by ammonium sulphate, and showed resistance to heat (100 degrees C for 10 min), trypsin, lysozyme, beta-glucuronidase, DNase, RNase, acetone, ethyl ether, urea and mercaptoethanol; it was partially destroyed by pronase and inactivated at extreme pH values. Electron microscopy did not reveal any phage-like particles associated with bacteriocin activity.

Purification and partial characterization of an antibiotic produced by Myxococcus coralloides

A strain of Myxococcus coralloides producing an antibiotic capable of inhibiting growth of Gram-positive bacteria was isolated. Antibiotic production occurred during vegetative growth but not during myxospore formation. The antibiotic was extracted from the growth medium with chloroform and purified by adsorption on silicic acid and by preparative silica gel thin-layer chromatography. The purified antibiotic showed a resistance to heat, acid, alkali and proteolytic enzymes. Chromatographic and electrophoretic behavior as well as infrared, ultraviolet and mass spectra are presented.