Posterior polar cataract: Minimizing risks.

BACKGROUND: Comparing surgical outcomes of management of posterior polar cataract, a congenital cataract, which is difficult to manage surgically and has been associated with poor surgical outcomes. METHODS: 46 eyes of 38 patients with posterior polar cataract underwent phacoemulsification and PCIOL implantation. RESULTS: In a prospective analytical study, 46 eyes of 38 patients with posterior polar cataracts underwent surgery at a zonal hospital of the armed forces. The posterior polar cataract incidence was 1.23 per 1000 with confidence interval (CI) of 0.0012. Of the 46 eyes operated, 6 had a posterior capsular rupture (PCR) (13.04%). The PCR incidence in normal cataracts is reported at approx. 1.1%, whereas, various studies have reported incidence of 6-36% in posterior polar cataracts. 41 eyes achieved a visual acuity of 6/12 or better (89.13%) and 39 eyes of 6/9 or better (84.78%). 4 patients had amblyopia (8.6%), Two patients developed macular edema (4.34%). Mean follow-up was 7 months (range 3-11 months). There was no case of nucleus drop or retinal detachment. CONCLUSION: Posterior polar cataracts are a surgical challenge. With controlled surgery, well defined techniques, a good surgical outcome can be achieved with reduced incidence of PCR.

Attitude and Practices of Mothers on Breastfeeding Attended at a Tertiary Hospital in Bangladesh.

This descriptive cross sectional study was conducted in Pediatric Out Patient Department (OPD) of Mymensingh Medical College Hospital (MMCH) from November 2013 to April 2014 to assess the knowledge and practices of the mothers about breastfeeding. Four hundred mothers having children 6 months to 2 years of age attended at OPD of MMCH for any cause were included in the study by systematic random sampling. A structured, pre-tested, interview schedule was used to collect data from mothers. All mothers were continuing to breastfeed their children. Two hundred and seventy-two (68.00%) infants received breast feeding within 1 hour after birth, while 128(32.00%) infants received breast feeding after 1 hour of birth. Of 128, in 48(37.50%) cases, mother's illness was the reason for delay in initiation of breast feeding, whereas in 70(54.69%) cases, it was due to reduced milk production on mother's statement. Pre-lacteal feeding was given in 96(24.00%) children. Among them honey was given in 24(25.00%) cases, cow's milk was given in 14(14.58%) cases, sugar water was given in 18(18.75%) cases and formula milk was given in 40(41.67%) cases. One hundred and twenty-eight (32.00%) mothers started to give their child food other than breast milk before 3 months of age and 148(37.00) mothers started to give their child food other than breast milk before 6 months of age. The reason for starting to give their child food other than breast milk before 6 months of age was mother's assumption of milk insufficiency in 166(60.14%) cases and baby's cry for hunger in 110(39.86%) cases. Formula milk was given in 120(30.00%) infants before 6 months of age. Among them 96(80.00%) mothers prepared it with larger amount of water. Plain water was given in 240(60.00%) children before the age of 6 months. One hundred and twenty-four (31.00%) children were exclusively breastfeed for first 6 months of age. Breastfeeding is almost universal in Bangladesh but the exclusive breastfeeding rate is alarmingly very low. Great emphasis is needed to educate mothers about benefits of colostrum, exclusive breastfeeding, and the harmful effects of pre-lacteal feeding.

Knowledge and practices of mothers on childhood diarrhoea and its management attended at a tertiary hospital in bangladesh.

This descriptive cross sectional study was conducted in Pediatric out Patient Department (OPD) of Mymensingh Medical College Hospital (MMCH) from March 2014 to August 2014 to assess the knowledge and practices of the mothers in acute diarrhoeal diseases in children under-five years of age regarding use of oral rehydration solution (ORS), zinc, other drugs and feeding practices. Four hundred children under-five years of age having acute diarrhoea were included in the study by systematic random sampling. A structured, pretested, interviewer-administered questionnaire was used to collect data from mothers of children having diarrhoeal diseases. ORS was offered by 360(90.00%) of the mothers. Out of which 279(77.50%) used it by their own knowledge. One hundred and ninety-one (53.06%) mothers prepared it correctly, while 169(46.94%) prepared it incorrectly. Of 169, 129(35.83%) mothers used less amount of water, while 40(11.11%) mothers used much amount of water to prepare ORS. Of 360 mothers, 89(24.72%) mixed part of the content of ORS sachet at a time. Of 360 mothers, only 55(15.28%) offered correct amount of ORS after each purging. Zinc was offered in 142(35.50%) children. Of 400, only 13(3.25%) mothers used recommended home-based fluid, while 70(17.50%) mothers offered increased amount of fluid to their child. Drugs other than zinc and ORS were used in 247(61.75%) children. Among drugs, other than zinc and ORS, antibiotics was used in 109(44.13%) cases, whereas antiprotozoal in 97(39.27%) cases. Amount of liquid given was more than usual in 70(17.50%) children, same as usual in 57(14.25%) children and less than usual in 273(68.25%) children. Amount of food given was same as usual in 59(14.75%) children, while less than usual in 341(85.25%) children. Control of diarrhoeal diseases programme is successful in introducing ORS at mass level. Great emphasis is needed to educate mothers about preparation and quantity of ORS to be given to children with diarrhoeal diseases.

Effects of nebulized budesonide as an adjunct to standard treatment of asthma exacerbations: a randomized, double-blind, placebo-controlled trial.

This study was done to determine the effects and outcome of inhaled budesonide in addition to standard management of asthma exacerbations in pediatric age groups. A randomized, double-blind, placebo controlled trial was done in a tertiary care urban hospital. Sixty six children aged 5 to 15 years with moderate to severe asthma exacerbations were eligible. All patients received a single dose of prednisolone 1mg/kg orally as first dose of systemic corticosteroids and then salbutamol (0.15mg/kg) and ipratropium bromide (500mcg) was nebulized every 20 minutes for 3 doses and then hourly for 2 hours as a part of standard treatment of asthma exacerbations. The intervention was 2mg (4mL) of budesonide or 4mL of normal saline which was nebulized immediately after the 1st dose of nebulized salbutamol and ipratropium bromide. The baseline characteristics of the budesonide group (n=33) and placebo group (n=33) were similar, but at 1 hour, 2 hour and 3 hour PEFR, respiratory rate, pulse rate, SaO2 and asthma score were significantly improved in the budesonide group compared to placebo group (p<0.01). The positive immediate effect of nebulized budesonide added to standard treatment of asthma exacerbations is an encouraging finding for further investigations of its routine use in the treatment of asthma exacerbations in children.

Relationship between Clinical Profile, Severity and Outcome of Community Acquired Pneumonia with Hyponatremia in Children Aged 2-60 Months.

Hyponatremia is the most common electrolyte imbalance seen in clinical practice and a common laboratory findings in children with community acquired pneumonia. This study aimed to find out relationship between clinical profile, severity and outcome of community acquired pneumonia with hyponatremia in children aged 2-60 months. This descriptive cross-sectional study was done in pediatrics department of Mymensingh Medical College Hospital, Bangladesh. Study period was 6 month from November 2016 to April 2017. Data were collected from 2 months to 60 months old children who fulfill the selection criteria. In this study sampling technique was purposive. Detailed history was taken, and meticulous examinations and relevant investigations were performed. 100 patients with community acquired pneumonia were enrolled, 34.0% patient had hyponatremia and 66.0% patients had no hyponatremia. Hyponatremia is more marked (45.5%) in severe pneumonia followed by moderate pneumonia (33.3%) and no hyponatremia found in mild pneumonia. Mean temperature, respiratory rate, heart rate, head nodding, nasal flaring, grunting, stridor, cyanosis, convulsion, feeding problem, Poor air entry were significantly higher in patient of pneumonia with hyponatremia when compared to patient of pneumonia without hyponatremia. Mean duration of symptoms and mean duration of hospital stay were also significantly higher in patient of pneumonia with hyponatremia. The mean serum sodium concentration was 132.18±1.51mmol/L in hyponatremic patients and 137.91±1.94mmol/L in normonatremic patients. Mean values of total leucocyte count, ESR, and C-reactive protein were significantly higher in patient of pneumonia with hyponatremia. Serum hemoglobin was significantly lower in hyponatremic patients than normonatremic patients. Maximum (55.9%) patients of community acquired pneumonia (CAP) with hyponatremia had patchy opacity, 26.5% had consolidation, 11.8% had interstitial opacity and 5.9% had pneumatocele. All the patients were treated with appropriate antibiotics and fluid and discharged after complete recovery without any complication. There was no death in the study population. From this study we can conclude that, hyponatremia is directly related with the severity of community acquired pneumonia (CAP). The intensity of clinical profile and investigation findings are also directly related with the severity of pneumonia.

Comparative Study of Serum IgE Level in Frequent Relapse and Infrequent Relapse Nephrotic Syndrome in Children.

Nephrotic syndrome (NS) represents a heterogenous group of glomerular disorders occurring mainly in children. Accumulated data suggest that patient with NS have an immunological basis. This cross-sectional comparative study was conducted in the Department of Paediatrics, Mymensingh Medical College Hospital (MMCH), Mymensingh during the period of March 2018 to October 2019 to determine the relationship of serum IgE level in frequent relapse and infrequent relapse nephrotic syndrome in children. Thirty cases of frequent relapse and 30 cases of infrequent relapse idiopathic nephrotic syndrome who were admitted in Department of Paediatrics, MMCH were included in this study by purposive sampling technique. After admission written informed consent from parents or guardians obtained. Serum IgE level was measured in all patients of idiopathic nephrotic syndrome during relapse and again four weeks after steroid therapy when patient was in remission. Serum total IgE levels were measured by ADVIA centaur CP immunoassay system. Most of the patient's age was within 2-6 years in both groups. Male children were predominant in both groups. Most of the patients came from rural area. Frequency of relapse per year was significantly higher and 24 hours urine output was significantly lower in frequent relapse nephrotic syndrome than that of infrequent relapse nephrotic syndrome. Significantly higher mean IgE was found in children with frequent relapse nephrotic syndrome (1439.8±388.5 IU/ml during relapse and 852.3±103.7 IU/ml at remission) than infrequent relapse nephrotic syndrome (1109.5±248.3 IU/ml during relapse and 776.6±108.5 IU/ml at remission) at both relapse and remission state. A linear, positive, significant correlation was found between rate of relapse and serum IgE level (Pearson correlation coefficient, r=0.674). Based on results it is concluded that serum IgE is high in relapsing nephrotic syndrome and it is persistently and significantly higher in frequent relapse nephrotic syndrome than infrequent relapse nephrotic syndrome.

Study on Blood Pressure Profile in School Children of Mymensingh City.

High blood pressure and its related problems are progressively assuming public health dimensions in developing countries like Bangladesh. There was a suggestion that hypertensive process can be aborted in its early stages. But it is poorly understood in its early stages. So, early natural history of hypertension and its evolution from the youth needs to be investigated. Objective of this study was to determine blood pressure distribution in school children aged 6-15 years. This descriptive cross-sectional study was conducted in the Department of Paediatrics, Mymensingh Medical College, Mymensingh, Bangladesh from November 2014 to October 2015. The sample was collected by simple random sampling from five different schools of Mymensingh after applying inclusion and exclusion criteria. After taking proper history and doing relevant examination, both systolic and diastolic BP was recorded by auscultatory method. Out of 994 children, 480(48.29%) were boys and 514(51.71%) were girls. In boys, the mean±SD of systolic and diastolic blood pressure (BP) were 105.9±10.8 mm of Hg and 67.4±6.7 mm of Hg and in girls it was 106.1±11.8 and 67.5±6.9 mm of Hg respectively. Systolic BP was found higher in girls belongs to 10-13 years. The study has shown that BP rises linearly with age and both systolic and diastolic BP has a significant positive correlation with age, sex, height and BMI in both sexes. This study also showed, 46(4.6%) children were hypertensive and 89(8.9%) were pre-hypertensive. Hypertension was found more in girls but there was no significant difference between two sexes. Hypertension was found more in relation to overweight, obesity and family history of hypertension. Hypertension is not uncommon in children. Routine blood pressure measurement should be conducted in all children.

Efficacy of Nebulized Hypertonic Saline (3%) Versus Normal Saline and Salbutamol in Treating Acute Bronchiolitis in A Tertiary Hospital: A Randomized Controlled Trial.

Acute bronchiolitis is a viral respiratory illness of infants and young children that occurs in the first two years of life. It is a major cause of hospital admissions in Bangladesh. Management of bronchiolitis is a great challenge for the pediatrician both in the outpatient and inpatient department. Because mainstay of treatment options are usually supportive like cool humidified oxygen, fluids, bronchodilators, epinephrine and corticosteroids. A number of agents have been proposed as adjunctive therapies, but their effects are controversial. Nebulized hypertonic saline (3%) has been reported to have some benefit in recent studies. So the objective of this study was to compare the efficacy of nebulized 3% hypertonic saline (HS) with salbutamol and normal saline (0.9%) nebulization in children with acute bronchiolitis. A double-blind randomized controlled trial was conducted in the Department of Paediatrics, Mymensingh Medical College Hospital, Bangladesh from November 2015 to October 2016. A total of 100 children aged one month to two years with acute bronchiolitis admitted in the Pediatric wards of MMCH were included in the study and were randomly assigned to either 3% nebulized hypertonic saline (n=50) or to 0.9% nebulized isotonic saline with salbutamol solution (n=50). The main outcome variables were clinical severity score, length of hospital stay, duration of oxygen therapy and oxygen saturation (SpO2). The therapy was repeated three times on every hospitalization day and the outcome was evaluated two times daily (12 hourly) for 60 hours. Mean duration of oxygen therapy in study group was 33.6±21.7 hours and in control group was 36.8±22.5 hours. But their difference was not statistically significant (p>0.05). The mean clinical severity score and mean oxygen saturation of the entire study patients in both groups decreased and increased respectively during hospital stay. There was significant difference of mean clinical severity score and oxygen saturation between admission and follow up-5 in each group (p<0.001). But their difference between two groups was not statistically significant (p>0.05). Mean duration of hospital stay was 2.91±1.54 days in study group and 3.09±1.85 days in control group. But their difference between two groups was not statistically significant (p>0.05). So in acute bronchiolitis nebulized hypertonic saline (3%) is as effective as normal saline (0.9%) and salbutamol nebulization.

Comparison of Growth of School Children in Mymensingh City Area, Bangladesh Using the 2000 CDC Standards and 2007 WHO Standards.

Growth assessment is an essential component of child health surveillance. The most influential tool in the growth assessment is the growth chart. Growth parameters of children are usually interpreted in relation to international standards like the NCHS/1977, CDC/2000 and WHO/2007 growth charts. This comparative study was carried out in the Department of Paediatrics, Mymensingh Medical College, Mymensingh, Bangladesh from November 2014 to October 2015 to compare the growth parameters of children using 2000 CDC standards and 2007 WHO standards. A total of five hundred healthy school children, aged 6 to 10 years were randomly selected proportionately from each class of five government primary schools from Mymensingh city area. Children with physical deformities and acutely ill and those with chronic debilitating diseases were excluded from the study. The mean and median weight, height and BMI were calculated for each age and sex. The median weight, height and BMI were then standardized by converting them to Z-scores (SD) for comparing against known reference values of 2000 CDC and 2007 WHO charts. Among 500 children, 252(50.4%) were boys and 248(49.6%) were girls. The mean age was found 8.0±1.42 years in boys and 8.04±1.42 years in girls. The mean weight was found 24.4±6.36kg in boys and 24.08±6.35kg in girls. The mean height was 125.90±10.16cm in boys and 125.38±10.74cm in girls. The mean weight, height and BMI of boys and girls were found to be lower in all age groups with compared to 2000 CDC standard and 2007 WHO standard but were closer to the WHO standards compared to the CDC standards. According to CDC and WHO in the study it was observed that underweight was found 16.3% and 14.7%, stunting 7.1% and 6.7%, overweight 6.7% and 8.7%, and obese 2.8% and 4.0% respectively in male subjects. On the other hand, in female subjects it was observed that according to CDC chart and WHO chart underweight was found 19.4% and 13.3%, stunting 6.0% and 4.8%, overweight 7.3% and 8.1% and obese 2.0% and 2.0% respectively. The findings in this study imply that growth pattern of Bangladeshi school children is closer with WHO standards and wider from CDC standards.

Magnetic ground states of Ce3TiSb5, Pr3TiSb5and Nd3TiSb5determined by neutron powder diffraction and magnetic measurements.

TheR3TiSb5ternary compounds, withRa light rare earth (La to Sm) have been reported to crystallize with the anti-Hf5CuSn3-type hexagonal structure (Pearson's symbolhP18; space-groupP63/mcm, N. 193). An early article that reported possible superconductivity in some of these intermetallic phases (namely those withR= La, Ce, and Nd) caught our attention. In this work, we have now refined the crystal structure of theR3TiSb5compounds withR= Ce, Pr and Nd by Rietveld methods using high-resolution neutron powder diffraction data. The magnetic ground states of these intermetallics have been investigated by low-temperature magnetization and high-intensity neutron diffraction. We find two different magnetic transitions corresponding to two related magnetic structures atTN1= 4.8 K (k1= [0, 1/2, 1/8]) andTN2= 3.4 K (k2= [0, 0, 1/8]), respectively for Ce3TiSb5. However, the magnetic ordering appears to occur following a peculiar hysteresis: thek2-type magnetic structure develops only after thek1-type phase fraction has first slowly ordered with time and the size of the ordered Ce3+magnetic moment has become large enough to induce the second magnetic transition. AtT= 1.5 K the maximum amplitude of the Ce moment in the coexisting phases amounts toµCe= 2.15 µB. For Nd3TiSb5an antiferromagnetic ordering belowTN= 5.2 K into a relatively simpler commensurate magnetic structure with a magnetic moment ofµNd= 2.14(3)µBand magnetic propagation vector ofk= [0, 0, 0], was determined. No evidence of superconductivity has been found in Nd3TiSb5. Finally, Pr3TiSb5does not show any ordering down to 1.5 K in neutron diffraction while an antiferromagnetic ground state is detected in magnetization measurements. There is no sign of magnetic contribution from Ti atoms found in any of the studied compounds.

Anisotropic magnetic properties of trigonal ErAl2Ge2 single crystal.

We report the anisotropic magnetic properties of the ternary compound ErAl2Ge2. Single crystals of this compound were grown by high temperature solution growth technique,using Al:Ge eutectic composition as flux. From the powder x-ray diffraction we confirmed that ErAl2Ge2 crystallizes in the trigonal CaAl2Si2-type crystal structure. The anisotropic magnetic properties of a single crystal were investigated by measuring the magnetic susceptibility, magnetization, heat capacity and electrical resistivity. A bulk antiferromagnetic ordering occurs around 4 K as inferred from the magnetic susceptibility and the heat capacity. The susceptibility is larger along the ab-plane and flattens out below the magnetic transition temperature ([Formula: see text]) and the magnetization in the ordered state increases more rapidly along the ab-plane than along the c-axis suggesting that the moments are inclined more towards the ab-plane. The magnetic susceptibility, magnetization and the 4f -derived part of the heat capacity in the paramagnetic regime analysed based on the point charge model of the crystalline electric field (CEF) indicate a relatively low CEF energy level splitting.

Inhibition of eukaryotic DNA replication by geminin binding to Cdt1.

In all eukaryotic organisms, inappropriate firing of replication origins during the G2 phase of the cell cycle is suppressed by cyclin-dependent kinases. Multicellular eukaryotes contain a second putative inhibitor of re-replication called geminin. Geminin is believed to block binding of the mini-chromosome maintenance (MCM) complex to origins of replication, but the mechanism of this inhibition is unclear. Here we show that geminin interacts tightly with Cdt1, a recently identified replication initiation factor necessary for MCM loading. The inhibition of DNA replication by geminin that is observed in cell-free DNA replication extracts is reversed by the addition of excess Cdt1. In the normal cell cycle, Cdt1 is present only in G1 and S, whereas geminin is present in S and G2 phases of the cell cycle. Together, these results suggest that geminin inhibits inappropriate origin firing by targeting Cdt1.

The Yb(2)Al(1-x)Mg(x)Si(2) series from a spin fluctuation (x = 0) to a magnetically ordered ground state (x = 1).

The structural and magnetic properties of Yb(2)Al(1-x)Mg(x)Si(2) (x = 0, 0.5 and 1), crystallizing in the tetragonal Mo(2)FeB(2)-type structure, are reported in this work. Yb(2)AlSi(2) exhibits a Pauli paramagnetic ground state arising due to spin/valence fluctuations induced by a significant Yb 4f conduction band hybridization. High-field magnetization (up to 120 kOe) indicates a nearly temperature-independent susceptibility of 8.6 × 10(-3) emu/Yb mol below 10 K. On the other hand, Yb ions in Yb(2)MgSi(2) order antiferromagnetically at a relatively high temperature T(N) of 9.5 K. The intermediate composition alloy Yb(2)Al(0.5)Mg(0.5)Si(2) is a Kondo lattice, antiferromagnet with T(N) = 5.5 K. The coefficient of the linear term of the electronic heat capacity, γ, of Yb(2)AlSi(2) is found to be 305 mJ mol(-1) K(-2), indicating a significant electronic mass enhancement due to strong electronic correlations. Below 12 K, an additional contribution to the heat capacity of the form T(3)lnT is observed. The (170)Yb Mössbauer spectra in the ordered state of Yb(2)MgSi(2) indicate a strong coupling of the 4f quadrupolar moment with the magnetic moment through a magneto-elastic coupling.

Pressure and magnetic field tuned quantum critical point in the Kondo antiferromagnet CePtZn.

We report magnetization, heat capacity and electrical resistivity measurements on CePtZn, which crystallizes in the orthorhombic TiNiSi type structure. Magnetization and electrical resistivity on the iso-structural series of compounds Ce(1-x)La(x)PtZn (x = 0.1, 0.2 0.5 and 1) were also carried out. The electrical resistivity of CePtZn was also measured in external magnetic fields up to 12 T and under pressures up to 2.66 GPa. We find that CePtZn is a dense Kondo lattice, ordering antiferromagnetically at T(N) = 1.7 K, with a comparable Kondo temperature. The magnetic transition temperature, T(N), is continuously suppressed both by the magnetic field and pressure and [Formula: see text] around 5-6 T and at 1.2 GPa, respectively. Non-Fermi liquid behavior of resistivity at 4 T and 1.2 GPa and logarithmic divergence of the heat capacity, C(4f)/T, at 6 T in a limited temperature region strongly suggest the emergence of a quantum critical point as [Formula: see text].

Magnetostructural behavior in the non-centrosymmetric compound Nd7Pd3.

A systematic study of the physical properties and microscopic magnetism of Nd7Pd3 compound, which in the paramagnetic state crystallizes in the non-centrosymmetric hexagonal Th7Fe3-type structure (hP20-P63 mc; with a = 10.1367(1) Å and c = 6.3847(1) Å at 300 K), confirms multiple magnetic ordering transitions that occur upon cooling. Antiferromagnetic transition is observed at T N = 37 K, which is followed by ferromagnetic transformation at T C = 33 K. The first-order magnetic transition at T C is magnetoelastic: it involves a change of crystal symmetry from P63 mc to Cmc21 and leads to anisotropic changes of the unit cell parameters. While the antiferromagnetic structure is symmetry allowed in P63 mc, the ferromagnetic structure with magnetic moments along the a-direction of the original hexagonal unit cell induces the first order transition to Cmc21. Density functional theory calculations confirm the experimentally observed ground state with the a-axis as the easy magnetization direction.

RelB regulates manganese superoxide dismutase gene and resistance to ionizing radiation of prostate cancer cells.

The relationship between NF-kappaB and resistance to radiation treatment in many tumor cell types has been generally well recognized. However, which members of the NF-kappaB family contribute to radiation resistance is unclear. In the present study, we demonstrate that RelB plays an important radioprotective role in aggressive prostate cancer cells, in part by the induction of antioxidant and antiapoptotic manganese superoxide dismutase (MnSOD) gene. RelB is both constitutively present and is inducible by radiation in aggressive prostate cancer cells. Using ectopically expressed dominant negative inhibitor, p100 mutant, and the siRNA approach, we demonstrate that selective inhibition of RelB significantly decreases the levels of MnSOD resulting in a significant increase in the sensitivity of prostate cancer cells to radiation treatment. These results demonstrate that RelB plays an important role in redox regulation of the cell and protects aggressive prostate cancer cells against radiation-induced cell death. Thus, inhibition of RelB could be a novel mechanism to radiosensitize prostate cancer.

Replication initiates at multiple dispersed sites in the ribosomal DNA plasmid of the protozoan parasite Entamoeba histolytica.

In the protozoan parasite Entamoeba histolytica (which causes amoebiasis in humans), the rRNA genes (rDNA) in the nucleus are carried on an extrachromosomal circular plasmid. For strain HM-1:IMSS, the size of the rDNA plasmid is 24.5 kb, and 200 copies per genome are present. Each circle contains two rRNA transcription units as inverted repeats separated by upstream and downstream spacers. We have studied the replication of this molecule by neutral/neutral two-dimensional gel electrophoresis and by electron microscopy. All restriction fragments analyzed by two-dimensional gel electrophoresis gave signals corresponding to simple Y's and bubbles. This showed that replication initiated in this plasmid at multiple, dispersed locations spread throughout the plasmid. On the basis of the intensity of the bubble arcs, initiations from the rRNA transcription units seemed to occur more frequently than those from intergenic spacers. Multiple, dispersed initiation sites were also seen in the rDNA plasmid of strain HK-9 when it was analyzed by two-dimensional gel electrophoresis. Electron microscopic visualization of replicating plasmid molecules in strain HM-1:IMISS showed multiple replication bubbles in the same molecule. The location of bubbles on the rDNA circle was mapped by digesting with PvuI or BsaHI, which linearize the molecule, and with SacII, which cuts the circle twice. The distance of the bubbles from one end of the molecule was measured by electron microscopy. The data corroborated those from two-dimensional gels and showed that replication bubbles were distributed throughout the molecule and that they appeared more frequently in rRNA transcription units. The same interpretation was drawn from electron microscopic analysis of the HK-9 plasmid. Direct demonstration of more than one bubble in the same molecule is clear evidence that replication of this plasmid initiates at multiple sites. Potential replication origins are distributed throughout the plasmid. Such a mechanism is not known to operate in any naturally occurring prokaryotic or eukaryotic plasmid.

Superconducting and charge density wave transition in single crystalline LaPt2Si2.

We present results of our comprehensive studies on single crystalline LaPt2Si2. Pronounced anomaly in electrical resistivity and heat capacity confirms the bulk nature of superconductivity (SC) and charge density wave (CDW) transition in the single crystals. While the charge density wave transition temperature is lower, the superconducting transition temperature is higher in single crystal compared to the polycrystalline sample. This result confirms the competing nature of CDW and SC. Another important finding is the anomalous temperature dependence of upper critical field H C2(T). We also report the anisotropy in the transport and magnetic measurements of the single crystal.

Probing the magnetic ground state of single crystalline Ce3TiSb5.

Motivated by the report of superconductivity in R3TiSb5 (R = La and Ce) and possibly Nd3TiSb5 at ∼4 K, we grew single crystals of La3TiSb5 and Ce3TiSb5 by the high-temperature solution method using Sn as a flux. While in both compounds we observed a superconducting transition at 3.7 K for resistivity and low-field magnetization, our data conclusively show that it arose from residual Sn flux present in the single crystals. In particular, the heat capacity data do not present any of the anomalies expected from a bulk superconducting transition. The anisotropic magnetic properties of Ce3TiSb5, crystallizing in a hexagonal P63/mcm structure, were studied in detail. We find that the Ce ions in Ce3TiSb5 form a Kondo lattice and exhibited antiferromagnetic ordering at 5.5 K with a reduced moment and a moderately normalized Sommerfeld coefficient of 598 mJ/mol K2. The characteristic single-ion Kondo energy scale was found to be ∼8 K. The magnetization data were subjected to a crystal electric field (CEF) analysis. The experimentally observed Schottky peak in the 4f-electron heat capacity of Ce3TiSb5 was reproduced fairly well by the energy levels derived from the CEF analysis.