Alterations in certain immunological parameters in the skin mucus of the carp, Cirrhinus mrigala, infected with the bacteria, Edwardsiella tarda

The bacterial fish pathogen Edwardsiella tarda causes heavy stock mortality, severely hampering fish production, resulting in great economic loss to the farming industry. The first biological barriers that confer immune protection against pathogen entry are the fish mucosal surfaces. The present study was undertaken to investigate the influence of E. tarda on certain enzymatic and non-enzymatic parameters in the skin mucous secretions of the fish Cirrhinus mrigala using spectrophotometry and zymography. Fish were randomly divided into three groups: control, vehicle control, and infected. A sublethal dose of E. tarda (2.2 × 106 CFU/fish) suspended in 50 μL of PBS was injected intra-peritoneally at 0 day (d). Subsequently, mucus samples were collected at 2 d, 4 d, 6 d and 8 d post-infection. The activities of lysozyme (LYZ), protease (PROT), alkaline phosphatase (ALP), acid phosphatase (ACP), catalase (CAT), peroxidase (PER), superoxide dismutase (SOD), and glutathione S-transferase (GST) decreased significantly in the skin mucus of the challenged fish, indicating the suppressed immune system and decreased antioxidant capacity of C. mrigala to E. tarda infection. Lipid peroxidation (LPO) and total nitrate-nitrite were significantly higher at several time points post-infection, suggesting that physiological functions have been impaired following pathogen challenge. The present findings could be relevant for fish aquaculture and underline the importance of skin mucus not only for assessing fish immune status but also for identifying early warning signals of disease caused by pathogens.

A retrospective study to assess the risk of bladder cancer in type-2 diabetic patients treated with pioglitazone

Introduction

Pioglitazone has been a cornerstone of oral hypoglycemic therapy. Concerns have been raised about its association with urinary bladder cancer. Considering the wide usage of this drug, concrete and multiple population-based studies are needed to establish the safety of this drug. The present retrospective study is aimed to assess the association of pioglitazone with urinary bladder cancer.

Materials and Methods

Clinical records of 4170 patients (2085 pioglitazone users and similar number of nonpioglitazone users) attending the diabetes clinic at a tertiary level teaching hospital were accessed, and the patients were subjected to symptom-directed questionnaire, urine examination, and cystoscopy and bladder biopsy (whenever clinically indicated). The risk of bladder cancer was also assessed with respect to cumulative dose and duration of pioglitazone.

Results

We did not observe any increased risk of bladder malignancy with pioglitazone exposure; furthermore, there was no association with cumulative dose and duration of pioglitazone therapy. Pioglitazone was found to be effective and safe in managing glycemic control in diabetic patients.

Non-equilibrium magnetic response of canonical spin glass and magnetic glass

Time and history dependent magnetization has been observed in a wide variety of materials, which are collectively termed as the glassy magnetic systems. However, such systems showing similar non-equilibrium magnetic response can be microscopically very different and they can be distinguished by carefully looking into the details of the observed metastable magnetic behavior. Canonical spin glass (SG) is the most well studied member of this class and has been extensively investigated both experimentally and theoretically over the last five decades. In canonical SGs, the low temperature magnetic state obtained by cooling across the SG transition temperature in presence of an applied magnetic field is known as the field cooled (FC) state. This FC state in canonical SG is widely believed as an equilibrium state arising out of a thermodynamic second order phase transition. Here, we show that the FC state in canonical SG is not really an equilibrium state of the system. We report careful dc magnetization and ac susceptibility measurements on two canonical SG systems, AuMn (1.8%) and AgMn (1.1%). The dc magnetization in the FC state shows clear temperature dependence. In addition, the magnetization shows a distinct thermal hysteresis in the temperature regime below the SG transition temperature. On the other hand, the temperature dependence of ac susceptibility has clear frequency dispersion below SG transition in the FC state prepared by cooling the sample in the presence of a dc-bias field. We further distinguish the metastable response of the FC state of canonical SG from the metastable response of the FC state in an entirely different class of glassy magnetic system namely magnetic glass, where the non-equilibrium behavior is associated with the kinetic-arrest of a first order magnetic phase transition.

Lattice strain accommodation and absence of pre-transition phases in Ni50Mn25+xIn25-x

The stoichiometric Ni₅₀Mn₂₅In₂₅Heusler alloy transforms from a stable ferromagnetic austenitic ground state to an incommensurate modulated martensitic ground state with a progressive replacement of In with Mn without any pre-transition phases. The absence of pre-transition phases like strain glass in Ni₅₀Mn_25+xIn_25-xalloys is explained to be the ability of the ferromagnetic cubic structure to accommodate the lattice strain caused by atomic size differences of In and Mn atoms. Beyond the critical value ofx= 8.75, the alloys undergo martensitic transformation despite the formation of ferromagnetic and antiferromagnetic clusters and the appearance of a super spin glass state.

Spin phonon coupling in Mn doped HoFeO3 compounds exhibiting spin reorientation behaviour

An investigation has been carried out on the spin phonon coupling in a series of isostructural polycrystalline orthorhombic (Space group Pnma) compounds HoFe_1-X Mn _X O₃ (x  ⩽  0.6) exhibiting spin reorientation below Néel temperature (T _N), using magnetization, neutron diffraction, and Raman scattering techniques. Mn doping leads to an anomalous increase in the spin reorientation temperature (T _SR), shifting it close to room temperature from T _SR ~ 60 K for x  =  0 sample, and concomitant lowering of T _N. The T _SR is absent in samples for x  ⩾  0.5. The magnetic structure undergoes a transition at T _SR from Γ₄  →  Γ₁ in the Mn doped compounds as against Γ₄  →  Γ₂ observed in HoFeO₃ sample. In the region T  <  T _N an anomalous softening of Raman phonon modes viz., B _2g(5) and B _3g(3), identified with the stretching motion and breathing mode, respectively, of Fe/Mn-O₆ octahedra, is observed in compounds exhibiting spin-reorientation behaviour, indicating a spin-phonon coupling in these compounds. A quadratic correlation between the deviation of phonon frequency and variation of antiferromagnetic moment (Δω [Formula: see text] M ²) is observed in these compounds. The temperature evolution of the M2+  mode obtained from the analysis of neutron diffraction data based on symmetry adapted mode decomposition of the Pnma structure further corroborates the mode softening observation.

Possible glass-like random singlet magnetic state in 1T-TaS2

Two-dimensional layered transition-metal-dichalcogenide compound 1T-TaS₂ shows the rare coexistence of charge density wave (CDW) and electron correlation driven Mott transition. In addition, atomic-cluster spins on the triangular lattice of the CDW state of 1T-TaS₂ give rise to the possibility of the exotic spin-singlet state in which quantum fluctuations of spins are strong enough to prevent any long range magnetic ordering down to the temperature absolute zero (0 K). We present here the evidences of a glass-like random singlet magnetic state in 1T-TaS₂ at low temperatures through a study of temperature and time dependence of magnetization. Comparing the experimental results with a representative canonical spin-glass system Au(1.8%Mn), we show that this glass-like state is distinctly different from the well established canonical spin-glass state.

Characterisation of cholinesterases in mucous secretions and their localisation in epidermis of Labeo rohita and Cirrhinus mrigala

Cholinesterases are multifunctional enzymes and have been associated with diverse physiological functions in addition to their classical role at synapses. In the present study, cholinesterase (ChE) isozymes have been characterised in mucous secretions and their activity has been localised in the epidermis of Labeo rohita and Cirrhinus mrigala. Zymography using specific substrates and inhibitors revealed the presence of two ChE isozymes-ChE-1 and ChE-2. The isozyme ChE-1 was characterised as an atypical butyrylcholinesterase and ChE-2 as a typical acetylcholinesterase in skin mucous secretions of both the fish species. Enzyme histochemical analysis demonstrated the presence of ChE activity in the epidermis of the fish species investigated. In both the fish species, strong ChE activity was observed in the outer-layer epithelial cells, taste buds and neuromasts. The middle and basal layer epithelial cells showed moderate to weak ChE activity. Club cells and mucous goblet cells showed the absence of ChE activity. Characterisation with specific inhibitors indicates that acetylcholinesterase (AChE) was the major cholinesterase type expressed in the epidermis of the two fish species investigated. Immunohistochemical localisation of apoptotic and cell proliferation markers, in addition, revealed high expression of active caspase 3 in the outer-layer epithelial cells, and proliferating cell nuclear antigen (PCNA) in the middle and basal layer epithelial cells. High ChE activity in caspase 3-positive cells in the outer layer of the epidermis and low in PCNA-positive cells in middle and basal layers could point towards the possible involvement of ChEs in cell death and their final extrusion from skin surface.

Unraveling the physical properties and superparamagnetism in anti-site disorder controlled Fe2TiSn

With an aim to control the anti-site disorder between Fe and Ti atoms in the full Heusler alloy, Fe[Formula: see text]TiSn, we substitute a small percentage of Ti at Fe site to form the Fe[Formula: see text]Ti[Formula: see text]Sn ([Formula: see text]) series. Using the incident x-rays tuned to the Fe K-edge absorption energy, we record the high resolution synchrotron x-ray diffraction profiles and unambiguously show the reduction in anti-site disorder. In particular, the Fe-Ti anti-site disorder decreases up to an excess Ti content of 0.07; further increase of Ti content leads to disorder between Ti-Sn sites. Detailed characterization vis-á-vis the excess Ti content has been carried out in terms of its thermal and electrical transport, and magnetic properties. Signatures of strong spin fluctuation are seen in all the physical properties reported here. The much disputed high value of the Sommerfeld constant has been shown to be a resultant of such strong spin fluctuations, thus ruling out the long standing controversy of heavy fermionic nature of Fe[Formula: see text]TiSn. Magnetization and the Seebeck coefficient show clear dependence on the disorder. Both dc and ac magnetic measurements reveal the low temperature superparamagnetic nature of this system, comprising of large magnetic clusters [Formula: see text]3 nm in size.

Alterations in the activity of certain enzymes in the gills of a carp Labeo rohita exposed to an azo dye, Eriochrome black T: a biochemical investigation

In Labeo rohita exposed to sub-lethal concentrations of an azo dye, Eriochrome black T for 4 days, gills show considerable alterations in the activity of certain metabolic enzymes-alkaline phosphatase, acid phosphatase, carboxylesterase, lactate dehydrogenase, and succinate dehydrogenase; and antioxidant enzymes-catalase and peroxidase. The activities of alkaline phosphatase, acid phosphatase, carboxylesterase, succinate dehydrogenase, catalase, and peroxidase decline significantly. This has been associated with impaired metabolic function of the gills due to azo dye toxicity. The activity of lactate dehydrogenase, in contrast, shows a gradual increase, reflecting a shift from aerobic to anaerobic metabolism. In the fish kept for recovery for 8 days, after exposing the fish to the dye for 4 days, activity of succinate dehydrogenase, alkaline phosphatase, and lactate dehydrogenase gradually become similar to control. Nevertheless, activity of acid phosphatase, catalase, peroxidase, and carboxylesterase, although recover gradually, remained significantly low as compared to that of control. This study signifies that the dye is highly toxic to Labeo rohita and suggests that the activity of metabolic and antioxidant enzymes can be used as biomarker for fish toxicity.

Role of aloin in the modulation of certain immune parameters in skin mucus of an Indian major carp, Labeo rohita

Enhancement of immune system seems to be the most promising method of preventing fish diseases. Several herbal products have immunostimulant properties, and are environmental friendly, economical and can act against a broad spectrum of pathogens. Present study was designed with an aim to evaluate the role of aloin, extracted from a herb Aloe barbadensis, in the modulation of certain immune parameters in an Indian major carp, Labeo rohita. Fishes were divided into control, vehicle control and aloin treated groups. Experiments were conducted for 7 days and fishes from the three groups were analyzed at 2d, 4d, 6d and 8d. The results demonstrated that at different intervals, L. rohita administered with aloin showed a significant increase in the activity of enzymes - lysozyme, protease, carboxylesterase, alkaline phosphatase, acid phosphatase, catalase and peroxidase, and non-enzymatic factors hemagglutinin and alternate complement compared with that of the controls. Thus, it can be concluded that administration of aloin is beneficial in enhancing the immune response and hence it can be used as potent immunostimulant in aquaculture.

Possible half-metallicity and variable range hopping transport in Sb-substituted Fe2TiSn Heusler alloys

The investigation of the magnetotransport properties on [Formula: see text] [Formula: see text]Sb _x with 0 [Formula: see text] 0.6 are presented in this paper. The substitution of Sb in place of Sn decreases the anti-site disorder as evident from x-ray diffraction patterns as well as from transport properties measurement. The much-disputed upturn in low temperature electrical resistivity of [Formula: see text]TiSn has been demonstrated to be a result of weak localization induced by anti-site disorder. With increased Sb substitution (⩾25%) the metallic transport behavior of [Formula: see text]TiSn changes to semiconductor-like. At low temperature, carrier transport in such compositions occurs via the variable range hopping mechanism. Moreover, a systematic increase in the anomalous Hall voltage is observed with increasing Sb-content, attributable to a side jump or Berry phase curvature effect. Electrical resistivity in the entire temperature regime hints towards half metallicity of the system. Our ab initio electronic structure calculations using generalised gradient approximation formalism further supports the results of our magnetotransport study.

Erectile Dysfunction: An Underestimated Presentation in Patients with Diabetes Mellitus

INTRODUCTION

Erectile dysfunction (ED) is a common complication of diabetes mellitus. ED, like other sexual disorders, is often under-reported and under-diagnosed, as talking about sex is considered a taboo in our society.

METHODOLOGY

All the male patients with diabetes mellitus (with or without active complaints of ED) attending Medicine or Psychiatry OPD of the institute during the study period were enrolled in the study. They were investigated for their body-mass index (BMI), blood sugar and lipid profile; and were assessed on HAM-D, General Health Questionnaire-30, IIEF, sex myth checklist and QOL Instrument for Indian Diabetes Patients (QOLID).

RESULT AND DISCUSSION

In the present study, a total of 138 diabetic patients were assessed, and those with severe ED were found to have poor glycemic control, worse lipid profile, higher body mass index, later age of onset, and longer duration of untreated diabetes as compared to non-ED patients. ED patients also scored higher on depression rating scale, had poorer general health and quality of life (QOL). Early attention to ED in diabetic patients can improve general health and QOL of the sufferers.

CONCLUSION

DM patients with poor glycemic control and advanced age have a higher propensity of developing severe ED, which further deteriorates the already compromised health & QOL.

Alterations in the skin of Labeo rohita exposed to an azo dye, Eriochrome black T: a histopathological and enzyme biochemical investigation

Histopathological changes and alterations in the activity of certain metabolic and antioxidant enzymes were analyzed in the head skin of Labeo rohita, exposed to sublethal test concentrations of the azo dye, Eriochrome black T for 4 days, using 24 h renewal bioassay method. Hypertrophied epithelial cells, increased density of mucous goblet cells, and profuse mucous secretion at the surface were considered to protect the skin from toxic impact of the azo dye. Degenerative changes including vacuolization, shrinkage, decrease in dimension, and density of club cells with simultaneous release of their contents in the intercellular spaces were associated to plug them, preventing indiscriminate entry of foreign matter. On exposure of fish to the dye, significant decline in the activity of enzymes-alkaline phosphatase, acid phosphatase, carboxylesterase, succinate dehydrogenase, catalase, and peroxidase-was associated with the binding of dye to the enzymes. Gradual increase in the activity of lactate dehydrogenase was considered to reflect a shift from aerobic to anaerobic metabolism. On transfer of azo dye exposed fish to freshwater, skin gradually recovers and, by 8 days, density and area of mucous goblet cells, club cells, and activity of the enzymes appear similar to that of controls. Alteration in histopathology and enzyme activity could be considered beneficial tool in monitoring environmental toxicity, valuable in the sustenance of fish populations.

Study of the sign change of exchange bias across the spin reorientation transition in Co(Cr1-x Fe x )2O4 (x = 0.00-0.125)

We present the evolution of novel phenomena of magnetic compensation effect, exchange bias (EB) effect and the field induced anomalies in '[Formula: see text]' substituted multiferroic compound [Formula: see text]. A few percent of '[Formula: see text]' substitution for '[Formula: see text]' in [Formula: see text] results in the reversal of field cooled magnetization under low applied fields below compensation temperature T _comp. Further, increase in the field leads to the spin reorientation transition (T _SR). Signature of EB in a narrow temperature window in the vicinity of T _SR and its sign change across T _SR is observed. Magnitude of EB depends on the amount of compensation and rigidity of the spin reorientation. We also notice the appearance of positive EB below the lock-in transition (T _L). Presence of unidirectional anisotropy developed in the commensurate spin-spiral below T _L could be responsible for the appearance of EB below T _L.

Imatinib-induced dental hyperpigmentation in chronic myeloid leukemia in an adult female

The course of chronic myeloid leukemia (CML) has changed since the introduction of imatinib, and its side-effects are still being reported. We are reporting a case of a CML patient who presented to us with discoloration of the upper front teeth following 6 months of therapy with imatinib. On detailed evaluation, the patient was found to have imatinib-induced dental hyperpigmentation.

Transient 2(nd) Degree Av Block Mobitz Type II: A Rare Finding in Dengue Haemorrhagic Fever

Dengue has been a major problem as endemic occurs almost every year and causes a state of panic due to lack of proper diagnostic methods and facilities for proper management. Patients presenting with classical symptoms are easy to diagnose, however as a large number of cases occur every year, a number of cases diagnosed with dengue fever on occasion presents with atypical manifestations, which cause extensive evaluation of the patients, unnecessary referral to higher centre irrespective of the severity and therefore a rough idea of these manifestations must be present in the backdrop in order to prevent these problems. Involvement of cardiovascular system in dengue has been reported in previous studies, and they are usually benign and self-limited. The importance of study of conduction abnormalities is important as sometimes conduction blocks are the first sign of acute myocarditis in patients of Dengue Hemorrhagic Fever in shock. We present here a case of 2(nd) Degree Mobitz Type II atrioventricular AV block in a case of Dengue Hemorrhagic fever reverting to the normal rhythm in recovery phase and no signs thereafter on follow up.

Characterization of carboxylesterase in skin mucus of Cirrhinus mrigala and its assessment as biomarker of organophosphate exposure

Presence of carboxylesterase (CbE) activity in the skin mucus of Cirrhinus mrigala was investigated. CbE activity in skin mucus showed higher substrate preference for α-naphthyl acetate over p-nitrophenyl acetate. Four CbE isozymes-CbE-1, CbE-2, CbE-3, and CbE-4 were observed in skin mucus during zymography. The isozyme CbE-4 was characterized as typical serine esterase, whereas CbE-1, CbE-2, and CbE-3 were identified as sulphhydryl group-dependent serine esterases. In vitro treatment of skin mucus with the organophosphorus insecticide, Nuvan(®) showed strong inhibition of CbE activity. In vivo exposure of the fish to sublethal test concentrations (5 and 15 mg/l) of the insecticide also revealed significant inhibition of CbE activity in mucus. After the cessation of exposure, CbE activity recovered to its control level during the recovery periods. Thus, CbE activity in skin mucus could be considered a biomarker of the organophosphorus insecticide exposure to fish and a useful tool in monitoring environmental toxicity.

The first evidence of cholinesterases in skin mucus of carps and its applicability as biomarker of organophosphate exposure

The presence of cholinesterase (ChE) activity in skin mucus of three carps, Cirrhinus mrigala, Labeo rohita, and Catla catla and its applicability as biomarker of the organophosphorus insecticide exposure were investigated. Biochemical characterization, using specific substrates and inhibitors, indicated that measured esterase activity in skin mucus was mainly owing to ChEs. Significant difference in the proportion of acetylcholinesterase and butyrylcholinesterase activities was observed in skin mucus of three carps. Enzyme kinetic analysis, using the substrate acetylthiocholine iodide revealed significantly high Vmax value in C. catla compared to that in L. rohita and C. mrigala. In contrast, Vmax value using the substrate butyrylthiocholine iodide was significantly high in C. mrigala than in L. rohita and C. catla. In vitro treatment of skin mucus of three carps, with the organophosphorus insecticide Nuvan®, showed strong inhibition of ChE activities. In vivo experiments conducted using C. mrigala and exposing the fish to the sublethal test concentrations (5 and 15 mg/L) of the insecticide also revealed significant inhibition of ChE activity in mucus. In C. mrigala, exposed to the sublethal test concentrations of the insecticide for 4 days and then kept for recovery for 16 days, mucus ChE activity recovered to the control level. Thus, ChE activity in skin mucus could be considered a good biomarker of the organophosphorus insecticide exposure to fish and a useful tool in monitoring environmental toxicity.

Comparative analysis of innate immune parameters of the skin mucous secretions from certain freshwater teleosts, inhabiting different ecological niches

The innate immune system of fish is considered first line of defense against a broad spectrum of pathogens. Being a component of innate immunity and lying at the interface between fish and the aqueous environment, skin mucus plays a frontier role in protecting fish from infections. In the present study, skin mucus of Cirrhinus mrigala, Labeo rohita, Catla catla, Rita rita and Channa punctata, inhabiting different ecological niches, was analyzed to characterize potential innate immune factors such as lysozyme, proteases, phosphatases, esterase and sialic acid. The enzyme activities were high in bottom dweller species, C. punctata and C. mrigala, and low in clean water inhabiting species, L. rohita and C. catla. An inverse relationship was observed between the level of enzyme activity and the sialic acid content in these fish species. In R. rita, however, the levels of all factors were found to be low. Zymographic analysis with labeled Micrococcus lysodeikticus revealed three isoforms of lysozyme in C. punctata and two in each species, C. mrigala, L. rohita and C. catla. In R. rita, lysozyme could not be detected. Gelatin zymography revealed that serine and metalloproteases were the major mucus proteases in all fish species investigated. In addition, trypsin-like protease and Ca(++)-specific serine proteases were observed in skin mucus. Increased knowledge of these parameters could be useful in understanding the role of skin mucus in the innate immune system of fish species inhabiting different ecological niches.

Metallicity and ferromagnetism in nanosystem of charge ordered Nd0.5Sr0.5MnO3

The fascinating phenomenon of destabilization of charge/orbital order in Nd0.5Sr0.5MnO3 with the reduction of grain size is critically investigated. Based on our magnetic and transport experiments followed by a theoretical analysis, we analyze various possible mechanisms and try to delineate a universal scenario behind this phenomenon. We revisit this issue carefully and discuss various evidences from experiments in nano and bulk manganites on the absence of correlation between size reduction and pressure effects on manganites. We propose a phenomenological model based on enhanced surface disorder to explain the appearance of weak ferromagnetism and metallicity in nanosize Nd0.5Sr0.5MnO3 system. All evidence seems to suggest that the transport is mediated through the surface via enhanced density of states in the nanometric grains. We provide theoretical support for this by performing an ab-initio electronic structure calculation as well as from a recent numerical simulation and argue that the mechanism is likely to be general in all nanosize charge ordered manganites.

Low temperature cluster glass behavior in Nd5Ge3

Various experimental evidence obtained from dc and ac magnetization measurements indicates that Nd(5)Ge(3) undergoes a spin glass transition from a high temperature antiferromagnetic state. Below the Néel temperature of 49 K, it shows distinct properties that characterize a cluster glass state, thereby indicating that it is an example of a reentrant spin glass system. Dynamical behavior of the magnetic susceptibility and the magnetic relaxation clearly give evidence of frustration in the material. Geometric frustration arising from the triangular arrangement of Nd atoms seems to be the main reason behind the spin glass state. A field-induced structural distortion accompanying the Néel transition may also be responsible for the frustration and the spin glass state.

Correlation between reentrant spin glass behavior and the magnetic order-disorder transition of the martensite phase in Ni-Co-Mn-Sb Heusler alloys

We have performed ac susceptibility and dc magnetization measurements in Ni(50-x)Co(x)Mn(38)Sb(12) Heusler alloys. From the ac susceptibility measurements, the existence of reentrant spin glass (RSG) state is observed for x=0-5. It is found that the signature of RSG behavior diminishes with increase in x. This behavior is in contrast to the fact that the exchange bias field increases with x, which reveals that the origins of RSG and exchange bias are different in the present system. It is found that the system enters a frustrated ferromagnetic state just below the Curie temperature of the martensite phase (T(M)(C)) and then the RSG state at low temperature. The strength of the RSG state is critically dependent on the sharpness of the magnetic transition at (T(M)(C)). This proposition is further supported by the thermo-remanent magnetization and low field thermomagnetic measurements.

Signature effects of spin clustering and distribution of spin couplings on magnetization behaviour in Ni-Fe-Mo and Ni-Fe-W alloys

Spontaneous magnetization as a function of temperature is investigated for a number of disordered Ni-Fe-Mo and Ni-Fe-W alloys using superconducting quantum interference device magnetometry, with a focus on the low-T behaviour as well as the critical exponents associated with the magnetic phase transition. While the low-T magnetization is found to be well described by Bloch's T(3/2) law, extraordinary enhancements of the spin-wave parameter B and the reduced coefficient B(3/2) = BT(C)(3/2) are observed with increasing Fe dilution as compared to conventional 3d ferromagnets, whereas the critical amplitudes are found to decrease systematically. Recent locally self-consistent calculations of finite-temperature spin dynamics in a generic diluted magnet provide an understanding in terms of two distinct energy scales associated with weakly coupled bulk spins in the ferromagnetic matrix and strongly coupled cluster spins. In view of the similar behaviour observed in diluted magnetic semiconductors and other ferromagnetic alloys, it is proposed that these distinctive features corresponding to the three important temperature regimes provide macroscopic indicators of signature effects of spin clustering on the magnetization behaviour in disordered ferromagnets.

Antibacterial properties of the skin mucus of the freshwater fishes, Rita rita and Channa punctatus

OBJECTIVES

The skin mucus of Rita rita and Channa punctatus was investigated to explore the possibilities of its antibacterial properties.

MATERIALS AND METHODS

Skin mucus was extracted in acidic solvents (0.1% trifluoroacetic acid and 3% acetic acid) and in triple distilled water (aqueous medium). The antibacterial activity of the mucus extracts was analyzed, using disc diffusion method, against five strains of bacteria--the Gram-positive Staphylococcus aureus and Micrococcus luteus; and the Gram negative Escherichia coli, Pseudomonas aeruginosa and Salmonella typhi.

RESULTS

In both Rita rita and Channa punctatus, the skin mucus extracted in acidic solvents as well as in aqueous medium show antibacterial activity against Staphylococcus aureus and Micrococcus luteus. Nevertheless, the activity is higher in acidic solvents than that in aqueous medium. The acidic mucus extracts of Rita rita, show antibacterial activity against Salmonella typhi as well.

CONCLUSIONS

The results suggest that fish skin mucus have bactericidal properties and thus play important role in the protection of fish against the invasion of pathogens. Fish skin mucus could thus be regarded as a potential source of novel antibacterial components.

Influence of B-site disorder in La0.5Ca0.5Mn(1 - x)B(x)O3 (B = Fe, Ru, Al and Ga) manganites

We have investigated the influence of B-site doping on the crystal and magnetic structure in La(0.5)Ca(0.5)Mn(1 - x)B(x)O(3) (B = Fe, Ru, Al and Ga) compounds using neutron diffraction, small angle neutron scattering, magnetization and resistivity techniques. The B-site doped samples are isostructural and possess an orthorhombic structure in the Pnma space group at 300 K. A structural transition from orthorhombic to monoclinic is found to precede the magnetic transition to the CE-type antiferromagnetic state in a few of these samples. On doping with Fe, the charge and orbitally ordered CE-type antiferromagnetic state is suppressed, followed by growth of the ferromagnetic insulating phase in 0.02 ≤ x ≤ 0.06 compounds. At higher Fe doping in x > 0.06, the ferromagnetic state is also suppressed and no evidence of long range magnetic ordering is observed. In Ru doped samples (0.01 ≤ x ≤ 0.05), the ferromagnetic metallic state is favored at T(C)≈200 K and T(MI)≈125 K and no significant change in T(C) and T(MI) as a function of Ru doping is found. In contrast, with non-magnetic Al substitution for 0.01 ≤ x ≤ 0.03, the charge ordered CE-type antiferromagnetic state coexists with the ferromagnetic metallic phase. With further increase in Al doping (0.05 ≤ x ≤ 0.07), both CE-type antiferromagnetic and ferromagnetic phases are gradually suppressed. This behavior is accompanied by the evolution of an A-type antiferromagnetic insulating state. Eventually, at higher Al doping (0.10 ≤ x ≤ 0.13), this phase is also suppressed and the signature of a spin glass like transition is evident in M(T). Likewise, substitution with Ga is observed to induce similar effects to those described for Al doped samples. The presence of short ranged ferromagnetic ordering has been further explored using small angle neutron scattering measurements in a few of the selected samples.

Fe(3.3)Ni(83.2)Mo(13.5): a likely candidate to show spin-glass behaviour at low temperatures

Unlike other transition metals alloyed with a non-magnetic metal, alloys of Ni behave rather differently. This is because of the fragility of the local magnetic moment on Ni. NiMo and NiW do not show any spin-glass phase. However, addition of Fe can bolster the moment on Ni. We wish to study whether the alloy Fe(3.3)Ni(83.2)Mo(13.5), chosen near a composition where mean-field estimates suggest there could be a spin-glass phase, shows such a phase or not.

Suppression of itinerant ferromagnetism and a spin-glass-like state in Zn substituted La0.67Ca0.33MnO3

We examine the magneto-transport, static and dynamic magnetic responses of the single phase glassy insulating compound La(0.67)Ca(0.33)Mn(1-x)Zn(x)O(3) (x = 0.10). This compound undergoes a field induced metal-insulator transition and exhibits colossal magnetoresistance for H ≥ 2 T. Many experimental features, such as a frequency dependent cusp in the in-phase component of linear ac susceptibility at a temperature T'(f), a broad maximum (at T(a)) in the ZFC cooled thermo-magnetization close to T'(f), large thermo-magnetic irreversibility below T(a), non-saturation of magnetization at 5 K even under 12 T with a characteristic S shape in the virgin curve, monotonic increase of the coercivity at low fields under ZFC condition as one approaches the T'(f), logarithmic relaxation of thermo-magnetization and ageing effects below T(a) and a characteristic maximum in the magnetic viscosity below the spin-glass transition temperature (T(g)) indicate a spin-glass-like state at low temperatures. This is further substantiated by the absence of second order non-linear ac susceptibility, a characteristic negative maximum at T(g) in third order non-linear ac susceptibility (χ'(3)), the critical divergence of χ'(3) as a function of temperature and ac probe field and an unusually large linear term in the low temperature specific heat.

Unusual field dependence of remanent magnetization in granular CrO2: the possible relevance of piezomagnetism

We present low field thermoremanent magnetization (TRM) measurements in granular CrO(2) and composites of ferromagnetic (FM) CrO(2) and antiferromagnetic (AFM) Cr(2)O(3). TRM in these samples is seen to display two distinct timescales. A quasi-static part of remanence, appearing only in the low field regime, exhibits a peculiar field dependence. TRM is seen to first rise and then fall with increasing cooling fields, eventually vanishing above a critical field. Similar features in TRM have previously been observed in some antiferromagnets that exhibit the phenomenon of piezomagnetism. Scaling analysis of the TRM data suggest that presumably piezomoments generated in the AFM component drive the FM magnetization dynamics in these granular systems in the low field regime.

Stabilization of antiferromagnetism in CeFe(2) alloys: the effects of chemical and hydrostatic pressure

Effects of Al, Mn and Sb dopings in CeFe(2) and the effect of applied pressure have been investigated. Al doping gives rise to the FM-AFM transition and a reduction in the magnetic moment and T(C) values, clearly indicating the growth of the AFM component. Mn and Sb dopings only cause a reduction in the T(C) value. It is found that, in general, external pressure enhances the antiferromagnetism in both the pure and the doped alloys. Enhancement of the Ce 4f-Fe 3d hybridization as a result of doping and with the external pressure may be the reason for the stabilization of antiferromagnetism in these alloys.

Structural and magnetic ordering in La(0.5)Ca(0.5-x)Ba(x)MnO(3) (0 < x ≤ 0.5) manganite

We report a structural, magnetic and transport study in La(0.5)Ca(0.5-x)Ba(x)MnO(3) (0<x≤0.5) using neutron diffraction, magnetization and resistivity measurements. The samples crystallize in an orthorhombic structure with Pnma space group and no structural transition is observed with Ba doping. Substituting Ca with Ba leads to an increase in average A-site ionic radii, ⟨r(A)⟩ and cation size disorder (σ(2)). Consequently, the nature of magnetic ordering undergoes changes as a function of x. At low temperature for x≤0.1, the CE-type antiferromagnetic spin structure is stabilized, similar to the parent compound. At x = 0.15, the magnetic phase is a mixture of CE-type and A-type spin structure. For x≥0.2, the ferromagnetic phase is stabilized. The signature of orbital ordering in addition to spin and charge ordering is observed in all samples with x≤0.15. T(C), T(CO) and T(N) remain nearly constant for x≤0.2. The transport studies reveal that for samples x≤0.2, adiabatic hopping of small polarons governs the transport behaviour above T(CO) (∼160 K). A parallel combination of small polaron hopping and variable range hopping mechanisms is found to describe resistivity data below T(CO). At x = 0.2, an insulator to metal transition is observed as temperature is lowered, and at x = 0.5 the sample becomes metallic below 280 K. In the metallic regime, resistivity data follows the Bloch-Grüneisen model together with contributions from high frequency optical phonons and magnetic scattering. The experimentally established phase diagram from the present study is compared with theoretical studies in the intermediate electron-phonon interaction regime.

Strongly correlated superconductivity in Rh17S15

In this Letter, we report resistivity, susceptibility, heat capacity, and upper critical field studies on a polycrystalline Rh17S15 sample which exhibits superconductivity below 5.4 K. Detailed studies suggest that the superconductivity in this compound arises from strongly correlated charge carriers presumably due to the high density of states of Rh d bands at the Fermi level. Moreover, the Hall coefficient shows a sign change and increases at low temperature before the sample becomes a superconductor below 5.4 K.

First order magnetic transition in doped CeFe2 alloys: phase coexistence and metastability

First order ferromagnetic (FM) to antiferromagnetic (AFM) phase transition in doped CeFe2 alloys is studied with the micro-Hall probe technique. Clear visual evidence of magnetic phase coexistence on micrometer scales and the evolution of this phase coexistence as a function of temperature, magnetic field, and time across the first order FM-AFM transition is presented. Such phase coexistence and metastability arise as a natural consequence of an intrinsic disorder-influenced first order transition. The generality of these phenomena involving other classes of materials is discussed.

Endoscopic bladder neck suspension revisited: long-term results of Stamey and Gittes procedures

OBJECTIVE

To evaluate the long-term results of Stamey's and Gittes' procedures for genuine stress incontinence.

METHODS

72 needle procedures (34 Stamey; 38 Gittes) performed by a single surgeon between 1988 and 1994 were retrospectively reviewed. All patients had genuine stress incontinence on preoperative video-urodynamics. Review was at 3 months and thereafter clinically determined. Update information was gained by a patient satisfaction questionnaire.

RESULTS

Data were available for 9 years for the Stamey group (mean 8.4 years) and 6 years for the Gittes' (mean 5.3 years). At 3 months, 93% were dry. There was a gradual attrition with 38% of the Stamey and 14% of the Gittes patients remaining dry or improved at 5 years. At 9 years, only 28% of the Stamey patients maintained their improvement. 26% of the original cohort underwent a second procedure. All patients who had repeat needle operations have failed. 48 questionnaires (67%) were returned. Only 25% of patients expressed satisfaction with their operation.

CONCLUSION

Early success rates with endoscopic bladder neck suspension are replaced by long-term failures. The durability is poor with an ongoing recurrent incontinence rate. Repeat procedures are not worthwhile. Gittes' procedure appears to have an earlier failure rate compared to Stamey's operation.

Profile of placental alkaline phosphatase expression in human malignancies: effect of tumour cell activation on alkaline phosphatase expression

Cellular alkaline phosphatases (ALP) are increasingly recognised as important markers for monitoring tumour cell behaviour in human malignancies. Colorimetric, flow-cytometric, and immunocytochemical assays were employed to assess the influence of activation on expression of cellular ALP in human tumour cell lines. The results showed the following: (1) Testis tumour biopsies (16/16) unlike bladder (0/14) and head and neck (0/16) tumours showed positive staining for ALP, particularly the placental type, i.e. PLAP, although this was not always present on all the cells of non-seminoma biopsies. (2) The intensity of ALP expression differed widely in tumour cell lines. Based on biochemical analysis, the profile of ALP fell into two categories: (a) low expressing (MW 70 kD, placental type ALP) like Hep2 and KB lines, and (b) those expressing both low and high molecular (MW 95 kD) bands like testis lines Tera II and Ep2102. In all cases treatment of tumour cell lysates with heat prior to biochemical analysis showed the disappearance of the higher and sharpening of the lower molecular weight ALP band. (3) Exposure of tumour cells to epidermal growth factor (EGF) expressing EGF receptor led to a decreased ALP expression by as much as 54% as assessed by biochemical or flow-cytometric techniques. These data demonstrated that testis tumour tissues and cell lines expressed ALP which were different from others. The data also showed that exposure of tumour cell lines expressing EGFr to EGF resulted in suppression of ALP expression. These observations are consistent with the notion that EGFr and PLAP expression may be taken as a marker of proliferation and differentiation in human malignancies, respectively.

Repeat epididymovasostomies: are they worthwhile?

OBJECTIVE

To establish whether it is worthwhile repeating epididymovasostomy in men with persistent obstructive azoospermia.

PATIENTS AND METHODS

The study included 24 men with obstructive azoospermia, persisting after previous surgery for blockage in the body or tail of the epididymes, who underwent repeat epididymovasostomy proximal to the previous anastomoses. Semen was re-analysed after 6 and 12 months, and information about pregnancy self-reported or determined by postal survey.

RESULTS

The postoperative sperm concentration was >107 /mL in 15 patients (62%) and 10 female partners became pregnant (41%). Antisperm antibodies were present in nine patients and three of their partners became pregnant after the man received steroid therapy. Unilateral revision did not produce a favourable outcome.

CONCLUSION

Having defined a favourable group of men with obstructive azoospermia by scrotal exploration, i.e. those with caudal epididymal blocks and patent vasa deferentia, initial technical failure should not preclude surgical revision of the anastomoses in selected cases.

Naloxone-induced withdrawal in patients with buprenorphine dependence

Naloxone-induced withdrawal was studied in seven patients currently dependent only on injecting buprenorphine, within 3 to 6 hours of their last dose. Withdrawal severity began to rise from 5 minutes and reached a peak at 60 minutes after 1.2 mg naloxone given intravenously. The mean withdrawal severity score was significantly higher at 30, 60 and 90 minutes compared to the baseline. The most frequent withdrawal signs and symptoms were mydriasis, systolic hypertension, tachypnoea, muscle pains, yawning, anxiety, restlessness and craving.