Photo-induced high-temperature ferromagnetism in YTiO3

In quantum materials, degeneracies and frustrated interactions can have a profound impact on the emergence of long-range order, often driving strong fluctuations that suppress functionally relevant electronic or magnetic phases^1-7. Engineering the atomic structure in the bulk or at heterointerfaces has been an important research strategy to lift these degeneracies, but these equilibrium methods are limited by thermodynamic, elastic and chemical constraints⁸. Here we show that all-optical, mode-selective manipulation of the crystal lattice can be used to enhance and stabilize high-temperature ferromagnetism in YTiO₃, a material that shows only partial orbital polarization, an unsaturated low-temperature magnetic moment and a suppressed Curie temperature, T_c = 27 K (refs. ^9-13). The enhancement is largest when exciting a 9 THz oxygen rotation mode, for which complete magnetic saturation is achieved at low temperatures and transient ferromagnetism is realized up to T_neq > 80 K, nearly three times the thermodynamic transition temperature. We interpret these effects as a consequence of the light-induced dynamical changes to the quasi-degenerate Ti t_2g orbitals, which affect the magnetic phase competition and fluctuations found in the equilibrium state^14-20. Notably, the light-induced high-temperature ferromagnetism discovered in our work is metastable over many nanoseconds, underscoring the ability to dynamically engineer practically useful non-equilibrium functionalities.

Control of structure and spin texture in the van der Waals layered magnet CrSBr

Controlling magnetism at nanometer length scales is essential for realizing high-performance spintronic, magneto-electric and topological devices and creating on-demand spin Hamiltonians probing fundamental concepts in physics. Van der Waals (vdW)-bonded layered magnets offer exceptional opportunities for such spin texture engineering. Here, we demonstrate nanoscale structural control in the layered magnet CrSBr with the potential to create spin patterns without the environmental sensitivity that has hindered such manipulations in other vdW magnets. We drive a local phase transformation using an electron beam that moves atoms and exchanges bond directions, effectively creating regions that have vertical vdW layers embedded within the initial horizontally vdW bonded exfoliated flakes. We calculate that the newly formed two-dimensional structure is ferromagnetically ordered in-plane with an energy gap in the visible spectrum, and weak antiferromagnetism between the planes, suggesting possibilities for creating spin textures and quantum magnetic phases.

Nanoscale lattice dynamics in hexagonal boron nitride moiré superlattices

Twisted two-dimensional van der Waals (vdW) heterostructures have unlocked a new means for manipulating the properties of quantum materials. The resulting mesoscopic moiré superlattices are accessible to a wide variety of scanning probes. To date, spatially-resolved techniques have prioritized electronic structure visualization, with lattice response experiments only in their infancy. Here, we therefore investigate lattice dynamics in twisted layers of hexagonal boron nitride (hBN), formed by a minute twist angle between two hBN monolayers assembled on a graphite substrate. Nano-infrared (nano-IR) spectroscopy reveals systematic variations of the in-plane optical phonon frequencies amongst the triangular domains and domain walls in the hBN moiré superlattices. Our first-principles calculations unveil a local and stacking-dependent interaction with the underlying graphite, prompting symmetry-breaking between the otherwise identical neighboring moiré domains of twisted hBN.

Here, the authors investigate the lattice dynamics of twisted hexagonal boron nitride layers via nano-infrared spectroscopy, showing local and stacking-dependent variations of the optical phonon frequencies associated to the interaction with the graphite substrate.

Sensitivity and specificity of screening tools and smear microscopy in active tuberculosis case finding

SETTING

Community based five pulmonary tuberculosis (PTB) surveys among adults.

OBJECTIVES

Estimate sensitivity and specificity of screening tools for PTB and sputum microscopy.

METHODS

For each survey site, we estimated sensitivity and specificity of different screening criteria and microscopy against culture; pooled estimates were obtained using Random Effects Model.

RESULTS

Sensitivity of cough alone, screening for any symptom (persistent cough ≥2 weeks, fever or chest pain ≥1 month, hemoptysis), any symptom or history of anti-TB treatment (h/o ATT) were 56.2%, 66% and 71.2% respectively; specificities were 95.3%, 93.8% and 92.7% respectively. X-ray when used alone for primary screening had sensitivity and specificity of 76.6% and 97.3% respectively. When used along with screening for cough, these figures were 94.3% and 93.1%, and 100% and 97.3% when used with any symptom and h/o ATT. When used for secondary screening, sensitivity and specificity of X-ray was 66.8% and 87.8% respectively after primary screening for cough, 65.0% and 89.8% after screening for any symptom, and 67.1% and 86.7% when used after screening for any symptom or h/o ATT. Pooled sensitivity and specificity of smear was 46.2% and 99.3% respectively.

CONCLUSION

Program managers may use these estimates while evaluating algorithms for active case finding.

Abstract P3-05-13: The neo-epitope landscape of breast cancer: Implications for immunotherapy

Introduction: Immune checkpoint blockade is an effective immunotherapy for multiple cancers, including a subset of TNBCs. The clinical response to checkpoint blockade correlates with high tumor mutational burden. Cancer-induced mutations are predicted to generate new HLA-binding epitopes (neo-epitopes), which are potential targets of T cells. To determine the neo-epitope load in breast cancer, we developed a rapid bioinformatics pipeline and filtering strategy, EpitopeHunter, to identify and prioritize clinically relevant neo-epitopes from the landscape of somatic mutations. Here, we determined the specificity and frequency of neo-epitopes from the TCGA dataset of invasive breast cancers.

Methods: We analyzed 842 tumor and normal breast cancer exome sequencing from the TCGA dataset. Subgroup analysis was performed based on the IHC status of ER, PR and HER2: (i) TNBC (n=98); (ii) ER and/or PR(+), Her2(-) (n=604); and (iii) ER and PR(+/-), Her-2(+) (n=140). Cancer specific mutations were called uniformly for the aligned tumor and normal pairs using VarScan2. For each annotated non-synonymous mutation, we generated all possible neo-epitopes (up to 11-mers) including the mutant amino acid. HLA typing of A, B and C MHC class I genes of each patient was determined using the POLYSOLVER algorithm. We selected high affinity binding epitopes using the IEDB prediction algorithm based on the known epitopes to identify likely binding of each neo-epitope within the suite of patient-specific HLA alleles (IEDB score < 500). We then filtered the epitopes based on tumor transcript abundance using RNAseq expression for 837/842 patients. An expression value of FPKM > 2 was used as a cut-off for the expressed neo-epitopes.

Results: Total mutational burden was highest for TNBC (median=53, range: 2-1162); followed by ER and PR(+/-), Her-2(+) (median=40, range: 6-4983); and lowest for ER and/or PR (+), Her-2(-) (median=30, range: 0-5515). About 15% of the nonsynonymous mutations led to the generation of neo-epitopes. The neo-epitope load (high affinity neo-epitopes with IEDB score <500) is highly correlated with the mutational burden (R2= 0.8-0.9). Number of patients with at least one neo-epitope expressed in each category was: TNBC (n= 79/97, 81%); ER and/or PR(+), Her2(-) (n=478/600, 79%); and ER and PR(+/-), Her-2(+) (n=115/140, 82%). Overall, 672/837 patients have at least one predicted high affinity neo-epitope expressed, with an average of 14.7 (1-525) neo-epitopes expressed per patient.

Conclusions: We have developed a rapid bioinformatics pipeline, EpitopeHunter, for the identification of neo-epitopes from tumor sequencing data. Eighty percent of breast cancer patients have at least one expressed neo-epitope, which may serve as candidates for targeted immunotherapy.

Citation Format: Narang P, Chen M, Sharma AA, Anderson KS, Wilson Sayres MA. The neo-epitope landscape of breast cancer: Implications for immunotherapy [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P3-05-13.

Evaluation of variants of carbol fuchsin solution to stain acid-fast bacilli in-situ by the pot method

BACKGROUND

Ziehl-Neelsen (ZN) staining requires heating, and pre-stained smears contain viable bacilli.

OBJECTIVE

To evaluate four variants of carbol fuchsin solution by the pot method and compare the results with ZN staining, taking culture as gold standard.

METHOD

Five hundred sputum samples from presumptive tuberculosis cases were homogenised and divided into two parts. One part was subjected to routine ZN staining and culture on solid medium, the other was equally distributed into four pots. Equal quantities of the basic fuchsin (BF) variant were added to each pot. Variant I contained 2% BF with 10% phenol and 4% ammonium sulphate (PhAS), while Variant II had 0.6% BF with PhAS; Variants III and IV contained respectively 2% and 0.6% BF with 10% phenol only. After 1 h, smears were made from each pot and culture was performed on Löwenstein-Jensen medium. Smear results were compared with the ZN results and evaluated against culture.

RESULTS AND CONCLUSION

Variant III gave excellent results compared to ZN (κ = 0.97), with sensitivity, specificity, and positive and negative predictive values similar to those of ZN, taking culture as gold standard. Pot contents were negative for Mycobacterium tuberculosis culture.

Correlation between measures of hypoglycemia and glycemic improvement in sulfonylurea treated patients with type 2 diabetes in India: results from the OBSTACLE hypoglycemia study

BACKGROUND

This study aimed to assess correlation between measures of hypoglycemia and glycemic control in patients with type 2 diabetes mellitus (T2DM) treated with sulfonylureas.

MATERIALS AND METHODS

T2DM patients being initiated on a sulfonylurea (SU) on background of a failing oral antihyperglycemic regimen were followed up for 12 weeks. (HbA1c) was measured at baseline and end of follow-up. Hypoglycemia was assessed using Stanford Hypoglycemia Questionnaire at week 12.

RESULTS

Of the total 1069 patients enrolled, 950 were considered evaluable. A weak negative correlation was observed between end of follow-up HbA1c values and hypoglycemia score, using both linear regression analysis (correlation coefficient -0.12; P = 0.0002) and negative binomial regression (β slope -0.09; P = 0.0010). A similar correlation was also observed between change in HbA1c from baseline and hypoglycemia score (β slope -0.07; P = 0.0048). Mean HbA1c reduction was lowest (0.65 ± 2.27%) in patients not reporting any hypoglycemia and highest (1.28 ± 2.40%) in patients with hypoglycemia score greater than median of 2 (P = 0.0031). There was no correlation between hypoglycemia frequency and end of follow-up HbA1c values (P = 0.4111).

CONCLUSION

With addition of SU on a background of a failing oral anti-hyperglycemic regimen, the extent of glycemic control correlates directly with measures of patient reported hypoglycemia.

Comparision of Three Laboratory Tests for Detection of AmpC β Lactamases in Klebsiella Species and E. Coli

BACKGROUND AND OBJECTIVE

AmpC β lactamases are one of the important causes of drug resistance in gram negative bacteria. Failure to detect these enzymes in the laboratory has contributed to therapeutic failures but there are till date no standard guideline available. This study was therefore undertaken to evaluate three phenotypic laboratory tests and the inhibitors used in two of the tests to detect AmpC β lactamases produced by E. coli and Klebsiella species as they are most commonly isolated organisms.

METHODS

E. coli and Klebsiella isolates from different clinical samples were tested for ESBLs production as per CLSI guidelines and excluded from the study. The non-ESBLs isolates were then screened for AmpC β lactamases production, by cefoxitin and then confirmed by three different methods, i.e., Disc Potentiation Test (DPT) , Double Disc Synergy Test (DDST) and Modified Three Dimensional Test (M3DT) which in the absence of molecular methods, was taken as the gold standard. Boronic acid and cloxacillin were used as inhibitory agents in the Disc Potentiation and Double Disc synergy Tests.

RESULTS

A total of 2,933 isolates were tested out of which 165 isolates were detected as non ESBLs producers,135 (81.82%) when screened for AmpC β lactamases based on resistance to cefoxitin were labelled as positive. 30 (18.18%) cefoxitin sensitive isolates were labelled as probably non AmpC producers . M3DT, in addition to detecting all the 135 (100%) cefoxitin resistant isolates, also detected 5 (16.67%) cefoxitin sensitive isolates as AmpC producers. Other phenotypic tests, DPT and DDST with different inhibitors like boronic acid and cloxacillin in different potencies were all found to be less sensitive. The best results among these two methods were obtained with DDST using cloxacillin 500μg.

CONCLUSION

In the absence of recommended guidelines for AmpC detection, the study reports, among the tests performed, M3DT as the best phenotypic method for AmpC confirmation, as it is not only the most sensitive but also specific test for AmpC as it rules out the resistance due to other mechanisms like the porin channel.

Trends in the annual risk of tuberculous infection in India

SETTING

Twenty-four districts in India.

OBJECTIVES

To evaluate trends in annual risk of tuberculous infection (ARTI) in each of four geographically defined zones in the country.

STUDY DESIGN

Two rounds of house-based tuberculin surveys were conducted 8-9 years apart among children aged 1-9 years in statistically selected clusters during 2000-2003 and 2009-2010 (Surveys I and II). Altogether, 184,992 children were tested with 1 tuberculin unit (TU) of purified protein derivative (PPD) RT23 with Tween 80 in Survey I and 69,496 children with 2TU dose of PPD in Survey II. The maximum transverse diameter of induration was measured about 72 h after test administration. ARTI was computed from the prevalence of infection estimated using the mirror-image method.

RESULTS

Estimated ARTI rates in different zones varied between 1.1% and 1.9% in Survey I and 0.6% and 1.2% in Survey II. The ARTI declined by respectively 6.1% and 11.7% per year in the north and west zones; no decline was observed in the south and east zones. National level estimates were respectively 1.5% and 1.0%, with a decline of 4.5% per year in the intervening period.

CONCLUSION

Although a decline in ARTI was observed in two of the four zones and at national level, the current ARTI of about 1% in three zones suggests that further intensification of TB control activities is required.

Comparison of disc and MIC reduction methods with polymerase chain reaction for the detection of metallo-β-lactamase in Pseudomonas aeruginosa

PURPOSE

The present study was undertaken to evaluate the screening antibiotic, confirmatory phenotypic test and agent against PCR as gold standard and to detect the prevalent MBL gene.

MATERIALS AND METHODS

Three hundred and twenty-six Pseudomonas aeruginosa isolates were screened for resistance to Imipenem (IPM), Meropemem (MEM) and Ceftazidime (CAZ) by disc diffusion. Isolates resistant to any of these were considered screen test-positive for MBL and were subjected to Double disc synergy test (DDST) and Disc potentiation test (DPT: Using IPM, MEM and CAZ alone and with EDTA), Minimum inhibitory concentration (MIC) reduction [four-fold or more reduction in MIC of IPM and MEM in presence of chelators: EDTA and 1,10-phenanthroline (EPI/EPM: EDTA-phenanthroline- Imipenem/Meropenem Broth Microdilution method)] and polymerase chain reaction (PCR) for blaIMP and blaVIM .

RESULTS

Screen test-positives by MEM and CAZ were 19.3% as against 17.8% by IPM. MEMDDST, DPT and EPM confirmed 100% screen-test positives as against 93.7% by CAZ DDST and DPT-2, 76.2% by CAZ DPT-1, 88.9% by IPM DDST, 85.7% by IPM DPT-1 and 92.1% by EPI. IPMand CAZ DDST together confirmed 100% while IPM and CAZ DPT-2 confirmed 96.8%. All 63 screen-test positives showed the presence of blaVIM .

CONCLUSIONS

MEM was found to be the best screening and confirmatory agent for MBL detection and blaVIM was found to be the prevalent MBL gene in this part of the country.

Management of choledochal cyst with portal hypertension

Portal hypertension (PHT) is a rare complication associated with choledochal cysts. Management issues of PHT patients are inadequately addressed, as its incidence is low and underlying causes variable. We report three cases of choledochal cyst with PHT. All patients had type IVa choledochal cysts, and the causes of PHT were secondary biliary cirrhosis (SBC) (two cases) and alcoholic liver disease (one case). Clinical presentation included jaundice, gastrointestinal bleeding and ascites. One patient with SBC successfully underwent excision with Rouxen-Y hepaticojejunostomy, while the patient with cholangitis was managed with endoscopic retrograde cholangiopancreatography stenting. The last patient with alcoholic liver disease was managed conservatively for seven years and died of liver failure. Management of choledochal cysts depends on the severity of liver disease in cases of cirrhosis of unrelated cause, while those with SBC should be considered for surgical management. Endoscopic stenting may be considered as a temporary measure in high-risk cases.

Isolation and identification of nontuberculous mycobacteria from water and soil in central India

Nontuberculous mycobacteria (NTM), important organisms in the Genus Mycobacterium and commonly present in the environment, are known to cause disseminated disease in AIDS patients. In this study, NTM were isolated from environment (soil and water) of the AIDS patients with disseminated NTM disease to know the prevalence of environmental NTM species and their correlation with clinical isolates from patients of the same area. Paraffin baiting technique was used to isolate NTM from environmental samples. Once isolated, subcultures were made on Lowenstein Jensen and Middlebrook 7H10 media and the species were identified using phenotypic and genotypic techniques. A total of 26 NTM isolates belonging to seven different species could be identified. Mycobacterium avium was the only species isolated from both clinical and environmental samples of the same patient; but the isolates did not match using PCR for IS 1311 and IS 1245 spacer sequences.

Disseminated disease caused by Mycobacterium simiae in AIDS patients: a report of three cases

Disseminated disease caused by Mycobacterium simiae, a slowly growing nontuberculous mycobacterium, has been rarely reported in the literature. We report on three AIDS patients who were found to suffer from mycobacteraemia caused by M. simiae in a rural tertiary-care hospital in central India.

Sensitivity of a whole-blood interferon-gamma assay among patients with pulmonary tuberculosis and variations in T-cell responses during anti-tuberculosis treatment

BACKGROUND

Interferon-gamma (IFN-gamma) assays are new tests for tuberculosis (TB) infection, and T-cell responses may be correlated with antigen burden. However, it is unclear if IFN-gamma assays can be used to monitor response to TB treatment.

MATERIALS AND METHODS

We measured T-cell responses to TB specific antigens in 60 Indian patients with microbiologically confirmed active pulmonary tuberculosis, before, during, and after TB treatment. Most patients were hospitalized and had moderate to advanced disease. IFN-gamma responses were measured using the commercial whole-blood Quanti-FERON-TB Gold In Tube (QFT-G) assay at three time-points: at diagnosis (N = 60), after 2 months of intensive treatment (N = 47), and at 6 months (treatment completion) (N = 39).

RESULTS

At baseline, 44 of 60 (73%) patients were positive by QFT-G. At the second time-point, 38 of 47 (81%) patients were positive. At treatment completion, 31 of 39 (79%) patients were positive. Changes in IFN-gamma responses over time were highly inconsistent--some individuals showed increases, while others showed decreases or no changes. Although the average IFN-gamma levels decreased slightly during treatment (not significant), the QFT-G sensitivity remained mostly unchanged during therapy.

CONCLUSIONS

Our data suggest that the QFT-G assay has modest sensitivity in patients with moderate to advanced pulmonary disease, but our results do not show a clear correlation between antigen burden and T-cell responses. Further research is needed to understand the kinetics of T-cell responses during TB treatment.

Evaluation of different methods for diagnosis of P. falciparum malaria

Rapid diagnosis is a prerequisite for institution of effective treatment and reducing the mortality and morbidity of falciparum malaria. This study was taken up to compare the efficacy of various rapid methods viz, acridine orange, Plasmodium falciparum histidine rich protein II antigen detection and Field's stain with traditional microscopy i.e, Leishman stain for diagnosing falciparum malaria. Thick and thin blood films of 443 consecutive patients with history of fever with chills and rigors were examined by Leishman and Field's method. Acridine orange stained wet mounts of blood were examined under fluorescence microscopy. All films were examined by two independent microbiologists. Plasmodium falciparum histidine rich protein II antigen was detected using commercially available kit, Paracheck Pf. Out of the 443 subjects examined for P.falciparum 18.28% were detected by Leishman stain, 6.32% by Field's stain, 18.28% by acridine orange and 18.1% by antigen based technique. Field's stain missed 53 (65.4%), while Paracheck Pf was negative in 6(7.4%) of the Leishman positive samples. All Field's stain and acridine orange positives were positive by Leishman, but five Paracheck Pf positives were negative. Leishman stain is cost effective but if facilities are available one should use acridine orange for screening. The antigen detection kits are rapid, simple and are useful but to rule out false negatives in clinically suspected cases, Leishman stain is reliable.

Candidacolonization in preterm babies admitted to neonatal intensive care unit in the rural setting

PURPOSE

Candida colonization in neonates results in significant morbidity and mortality. The purpose of this study was to determine colonization of Candida spp. in preterm babies and identify the risk factors.

METHODS

Swabs from oral, rectum, groin and umblicus of 103 preterm and 100 term neonates were obtained within 24 hours of birth, day three, day five, day seven and thereafter every week till the neonate was admitted in the neonatal intensive care unit (NICU). Swabs were also collected from the mother's vagina prior to delivery. Twice every month, air of the NICU was sampled by settle plate and swabs were collected from the hands of health care workers and inanimate objects of NICU. Identification and speciation was done by standard methods. Antibiotic sensitivity was studied against amphotericin B, ketoconazole and fluconazole by disk diffusion method.

RESULTS

Colonization with Candida was significantly higher in preterms. Earliest colonization was of oral mucosa and 77.1% of the preterms had colonised at various sites by the first week of life. Significant risk factors in colonized versus non-colonized preterms were male sex, longer duration of rupture of membranes (DROM), administration of steroids and antibiotics and vaginal colonization of mothers, whereas those in preterms versus terms were low birth weight and gestational age. C. albicans was the commonest species, both in the colonized preterms (45.9%) and vagina of mothers. Resistance was seen to fluconazole and ketoconazole only. No Candida spp. was isolated from health care personnel or environment.

CONCLUSIONS

Colonization of preterms by Candida is a significant problem in NICU and the significant risk factors observed in colonized preterms were male sex, longer DROM, administration of steroids and antibiotics and vaginal colonization of mothers.

Prevalence of tuberculous lymphadenitis in children in Wardha district, Maharashtra State, India

SETTING

Rural area of Wardha district, Maharashtra State, Central India.

OBJECTIVE

To determine the prevalence of tuberculous lymphadenitis in children aged 0-14 years in the study area and to assess factors that may contribute towards the prevalence.

DESIGN

House to house survey of a population of 23,229 in 35 neighbouring villages with 7900 children aged 0-14 years from May 1993 to May 1994 and from March 1995 to February 1996.

RESULTS

The prevalence of tuberculous lymphadenitis/1000 children was 4.43. The maximum prevalence was in the 5-9 years age group. The prevalence was 34 times higher in children with positive family history of tuberculosis than in those without a history. There was an association between prevalence and the living standards of the children, with a higher prevalence in families that belonged to an underprivileged social class living in thatched, improvised houses. Multiple cervical lymph nodes >2 cm and with matting and fluctuation were found to be characteristic clinical features.

CONCLUSION

The prevalence of peripheral lymphadenopathy was 27.2/1000 children and that of tuberculous lymphadenitis was 4.43/1000. Positive history of contact in the family was a significant epidemiological indicator of tuberculous glands.

Keratitis due toColletotrichum dematium- A case report

Colletotrichum dematium has been rarely reported from India before. The present case, a farmer, developed peripheral corneal ulcer five days following trauma with plant. At presentation his visual acuity was 6/60 (unaided) and 6/24P with pinhole. Slit lamp and fluorescent stain examination revealed paracentral corneal ulcer with irregular margins, stromal infiltration and multiple epithelial defects. Microbiological examination of corneal samples confirmed the initial diagnosis of fungal corneal ulcer and the fungus was identified as C.dematium. Patient was treated with topical natamycin and ciprofloxacin. Patient left against medical advice and was lost to follow up. This report emphasizes that Colletotrichum keratitis may not be rare. Early diagnosis may help in institution of specific therapy early in the disease.

Host choice promotes reproductive isolation between host races of the larch budmoth Zeiraphera diniana

The chances for sympatric speciation are improved if ecological divergence leads to assortative mating as a by-product. This effect is known in parasites that find mates using host cues, but studies of larch- and pine-feeding races of the larch budmoth (Zeiraphera diniana, Lepidoptera: Tortricidae) suggest it may also occur when mate attraction is via sex pheromones that are independent of habitat. We have previously shown that females releasing pheromones on or near their own host attract more males of their own race than if placed on the alternative host. This host effect would enhance assortative mating provided adults preferentially alight on their native hosts. Here we investigate alighting preferences in natural mixed forest using a novel likelihood analysis of genotypic clusters based on three semidiagnostic allozyme loci. Both larch and pine females show a realized alighting preference for their own host of 86%. The equivalent preferences of males were 79% for the larch race and 85% for the pine race. These preferences are also detectable in small-scale laboratory experiments, where alighting preferences of larch and pine races towards their own hosts were, respectively, 67 and 66% in females and 69 and 63% in males. Pure larch race moths reared in the laboratory had alighting choice similar to moths from natural populations, while hybrids were intermediate, showing that alighting preferences were heritable and approximately additive. The field estimates of alighting preference, coupled with earlier work on mate choice, yield an estimated rate of natural hybridization between sympatric host races of 2.2-3.8% per generation. Divergent alighting choice enhances pheromone-mediated assortative mating today, and is likely to have been an important cause of assortative mating during initial divergence in host use. Because resources are normally 'coarse-grained' in space and time, assortative mating due to ecological divergence may be a more important catalyst of sympatric speciation than generally realized.

Leptospirosis--a case report

Outbreaks of Leptospirosis have been reported from various parts of India including Maharashtra. We report a case of leptospirosis from Wardha District, Maharashtra from where the disease has not been reported so far.

Comparison of magnetic resonance cholangiography and percutaneous transhepatic cholangiography in the evaluation of bile duct strictures after cholecystectomy

BACKGROUND

Percutaneous transhepatic cholangiography (PTC) has been the preferred investigation to delineate the anatomy of the biliary tract in a patient with a bile duct stricture after cholecystectomy. Recently magnetic resonance cholangiography (MRC) has been described to evaluate the obstructed biliary tract. This paper reports a comparison of MRC with PTC in evaluating patients with an iatrogenic bile duct stricture.

METHODS

This was a prospective study of 26 patients who had surgery for a bile duct stricture after cholecystectomy. Before operation all patients underwent both MRC and PTC, the results of which were compared with the intraoperative findings.

RESULTS

Both PTC and MRC were comparable with regard to image quality, detection of intrahepatic bile duct dilatation, assessment of the level of injury and detection of abnormalities such as intraduct calculi, cholangitic liver abscesses and atrophy of liver lobes. MRC provided additional information in four patients, including detection of associated fluid collections (n = 3) and portal hypertension (n = 1). In eight patients more than one puncture had to be performed during PTC to delineate the complete anatomy.

CONCLUSION

MRC is an accurate and non-invasive imaging procedure for preoperative evaluation of patients with a bile duct injury after cholecystectomy, and is capable of providing additional information which may not be available with PTC.

Phakonit: phacoemulsification through a 0.9 mm corneal incision

Advances in technique and equipment have led to a significant increase in the popularity of phacoemulsification and have increased its safety and efficiency. We describe a technique, phakonit, in which the lens is emulsified through a 0.9 mm clear corneal temporal incision. A cortical wash with bimanual irrigation/aspiration is followed by enlarging the incision to 2.0 mm and inserting a Staar sub-2.0 mm foldable intraocular lens. Phakonit is a safe, precise method of phacoemulsification with minimal intraoperative or postoperative complications.

Bioterrorism: a threat for which we are ill prepared

Of the weapons of mass destruction, the biological ones are the most feared and bioterrorism has become one of the most vicious threats to civilized society in recent times. Biological weapons have been sporadically used for centuries. Despite international regulations, there has been a global re-emergence of the threat of biological warfare. As many as 17 countries are suspected of either including or developing biological agents in their weapons programmes. In the past decade, a number of terrorist organizations with access to bioweapons technology have emerged. Current surveillance systems may be inadequate to detect biological attacks. The onset of illness is often delayed, thus the timing and location of such an event may be extremely difficult to identify. We are unfamiliar with most of the agents of biological warfare and are ill-equipped to handle the consequences of such an attack. In addition, there is no apparent coherent policy to handle a biological terrorist incident. Given the enormity of what is possible in the event of a biological attack, we must be prepared to detect, diagnose, epidemiologically characterize and respond appropriately to biological weapons. Of the potential biological weapons, smallpox and anthrax pose the greatest threats.

Results of pediatric laser in situ keratomileusis

PURPOSE

To evaluate the results of laser in situ keratomileusis (LASIK) for uniocular high myopia in pediatric eyes.

SETTING

Dr. Agarwal's Eye Hospital, Chennai (Madras), India.

METHODS

Sixteen eyes that were treated by LASIK for uniocular high myopia were retrospectively analyzed. The mean patient age was 8.4 years +/- 1.83 (SD) (range 5 to 11 years). Laser in situ keratomileusis was performed using the Technolas Keracor 217 excimer laser and the Automated Corneal Shaper microkeratome, which created a 160 microm corneal lamellar flap. Postoperatively, patients were reviewed at 1 day, 1 week, and 1, 6, and 12 months. The examination included uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), refraction, anterior segment evaluation, grading of haze based on a 5-point scale, intraocular pressure, corneal topography, and fundus evaluation. The Student t test was used for statistical analysis.

RESULTS

The charts of all patients were analyzed at the 12 month visit. The mean preoperative spherical equivalent (SE) was -14.88 +/- 3.69 diopters (D) (range -9.00 to -23.00 D) and the mean postoperative SE, -1.44 +/- 1.14 D (range 0 to -2.50 D) (P < .05). The safety index was 1.01 (mean postoperative BCVA 0.54 and mean preoperative BCVA 0.53; P = .77). The efficacy index was 0.53 (mean postoperative UCVA 0.28 and mean preoperative BCVA 0.53). None of the eyes had an induced astigmatism of more than 0.5 D. Twelve eyes regained their BCVA, 2 lost 1 line of BCVA, and 2 gained 1 line. Three eyes had grade 2 haze. No retinal complications were observed.

CONCLUSION

In this study, LASIK for uniocular high myopia in pediatric eyes provided encouraging results in the management of select cases of anisometropic amblyopia when other measures failed. A larger study with a longer follow-up is necessary to determine the long-term effects.

Prevalence of sputum-positive pulmonary tuberculosis in tribal and non-tribal populations of the Ashti and Karanja tahsils in Wardha district, Maharashtra State, India

SETTING

Ashti and Karanja tahsils, Wardha district, Maharashtra State, Central India.

OBJECTIVE

To find and compare the prevalence of bacillary positive pulmonary tuberculosis amongst the different tribes and in the non-tribal population.

DESIGN

Prevalence study of pulmonary tuberculosis by house-to-house survey of symptoms among tribal (n = 20596) and non-tribal (n = 93 670) populations aged 5 years and over, between September 1989 and November 1990.

RESULTS

The prevalence of smear and/or culture-positive tuberculosis/100000 population was 133 in the tribal and 144 in the non-tribal population. The difference in prevalence of symptomatic individuals and sputum-positive cases among the tribal and the non-tribal populations was statistically significant only in the symptomatic individuals/100000 (P = 0.01). The prevalence of cases in both groups was higher in males than females; however this difference was significant only in the tribal group (P = 0.05). Only two of the 46 tribes encountered, the Mana and Pawara tribes, showed a high prevalence, of 730 and 612/100000, respectively. The three other tribes with positive cases (the Gond group) had prevalences comparable to that of the nontribal population.

CONCLUSION

The prevalence of tuberculosis in tribal people was comparable to that of the non-tribal population.

Safe pre-operative fasting times after milk or clear fluid in children. A preliminary study using real-time ultrasound

Gastric emptying of orange-flavoured glucose (group I), low-fat milk (group II) and breast milk (group III) was evaluated in 45 ASA grade I children of < or = 5 years of age by using real-time ultrasonography and residual gastric volume and pH was then measured. In 15 more children, residual gastric volume and pH was measured after a midnight fast (group IV). Mean (SD) gastric emptying time in group I was 1.53 (0.25) h (range 1.00-1.75), group II 2.32 (0.31) h (range 1.75-2.75) and group III 2.43 (0.27) h (range 2.00-2.75). According to Robert and Shirley's criteria, no children of group I and II were found to be 'at risk' at 2 h and 3 h, respectively, but 13.3% of group III children were labelled as 'at risk' at 3 h. The incidence of 'at risk' children in group IV was 33.3%. It was concluded that 3% fat milk or 17.5% glucose in a volume of 10 ml.kg-1 (maximum volume of 100 ml) can be given in children safely 3 h and 2 h, respectively, before anaesthesia. More real-time studies are required on breast milk to establish guidelines for its potential use as a pre-operative feed 3 h before anaesthesia.

Fractionation, analysis and diagnostic utility of Mycobacterium tuberculosis H37Ra excretory-secretory antigen in pulmonary tuberculosis

Excretory-secretory antigen of Mycobacterium tuberculosis H37Ra (Mtb ES antigen) isolated from culture filtrate was partially purified by 6% trichloroacetic acid precipitation. The TCA supernatant fraction (Mtb EST antigen) was examined for its diagnostic use in the detection of tuberculous IgG antibody in human sera by stick Indirect ELISA. Using Mtb EST antigen, tuberculous IgG antibody was detected in 90% of smear positive and 71% of smear negative pulmonary tuberculosis cases and 10% of healthy and disease controls. Further fractionation of Mtb EST antigen by SDS-PAGE yielded four active antigenic fractions viz., Mtb EST-3,4,6 and 10. Diagnostic evaluation of these fractions showed Mtb EST-6 antigen fraction to be useful in detection of both smear positive and smear negative pulmonary tuberculosis cases with sensitivities of 94% and 78% respectively and specificity of 88%.

Role of antineural antibodies in perpetuation of a pre-existing peripheral nerve damage in leprosy

This study was carried out in order to find out whether antineural antibodies had a role to play in perpetuating pre-existing nerve damage in leprosy. Indirect ELISA was carried out on sera from 20 leprosy patients and five normal controls using antigen prepared from peripheral nerves of a cured bacteriologically negative leprosy patient. None of the patients had significant levels of IgG antibodies whereas eight of them (40%) had significant levels of IgM antibodies. However, there was no correlation with duration of disease, treatment received, nerve enlargement or active neuritis. The nature of these antibodies is discussed.

The role of antiperipheral nerve antibodies in nerve damage in leprosy

The objective of this study was to determine the role of antineural antibodies in leprosy. Indirect ELISA using antigen prepared from normal human peripheral nerves was carried out on the sera from 100 leprosy patients and 18 normal controls. In total, 9% of the patients had demonstrable levels of IgG antineural antibodies and 11% had demonstrable levels of IgM antibodies. There was no correlation with the type of leprosy, bacteriological index, treatment taken, the presence of a reactional state, the presence of enlarged nerves or active neuritis.