A precision measurement of the mass of the top quark

The standard model of particle physics contains parameters--such as particle masses--whose origins are still unknown and which cannot be predicted, but whose values are constrained through their interactions. In particular, the masses of the top quark (M(t)) and W boson (M(W)) constrain the mass of the long-hypothesized, but thus far not observed, Higgs boson. A precise measurement of M(t) can therefore indicate where to look for the Higgs, and indeed whether the hypothesis of a standard model Higgs is consistent with experimental data. As top quarks are produced in pairs and decay in only about 10(-24) s into various final states, reconstructing their masses from their decay products is very challenging. Here we report a technique that extracts more information from each top-quark event and yields a greatly improved precision (of +/- 5.3 GeV/c2) when compared to previous measurements. When our new result is combined with our published measurement in a complementary decay mode and with the only other measurements available, the new world average for M(t) becomes 178.0 +/- 4.3 GeV/c2. As a result, the most likely Higgs mass increases from the experimentally excluded value of 96 to 117 GeV/c2, which is beyond current experimental sensitivity. The upper limit on the Higgs mass at the 95% confidence level is raised from 219 to 251 GeV/c2.

Search for narrow tt resonances in pp collisions at square root of (s)=1.8 TeV

A search for narrow resonances that decay into tt pairs has been performed using 130 pb(-1) of data in the lepton + jets channel collected by the Dphi detector in pp collisions at square root of (s)=1.8 TeV. There is no significant deviation observed from the standard-model predictions at a top-quark mass of 175 GeV/c2. We therefore present upper limits at the 95% confidence level on the product of the production cross section and branching fraction to tt for narrow resonances as a function of the resonance mass MX. These limits are used to exclude the existence of a leptophobic top-color particle with mass MX<560 GeV/c2, using a theoretical cross section for a width GammaX=0.012MX.

C3-4 level cervical spondylotic myelopathy

Cervical spondylotic myelopathy (CSM) is uncommon at the C3-4 level. Fourteen patients with C3-4 CSM were treated over a period of 3 years. The radiological factors contributing to CSM at the C3-4 level were studied. These factors included the assessment of static and dynamic canal diameters, retrolisthesis, posterior osteophytes and degenerative spinal segmental fusion on plain X-rays; and, the antero-posterior cord compression ratio (APCR) on magnetic resonance imaging (MRI). The clinical status of the patients was assessed by the modified Japanese orthopedic association scale (mJOAS). The mean difference between the static and dynamic canal diameters was statistically significant at C3-4 (p < 0.01). The APCR obtained at different levels showed a significant compression at the C3-4 level in comparison to the lower level. There was a correlation between the APCR and the preop mJOAS, r=0.6 (p< 0.05). The mean mJOAS improved from 9.35 to 14.35 at follo-up. The recovery rate calculated using the modified Hirabayashi rate was 66.9%. Degenerative changes at lower cervical segments predispose to increased mobility and spondylotic changes at the C3-4 level. The patients in this study were young as compared to those reported in the international literature.

Tamoxifen: a novel treatment for primary biliary cirrhosis?

Primary biliary cirrhosis (PBC) is a chronic cholestatic liver disease, which predominantly affects women. It is characterised histologically by necroinflammation of small intrahepatic bile ducts and biochemically by elevated serum alkaline phosphatase, levels of which at diagnosis predict survival. Ursodeoxycholic acid (UDCA) is the only treatment shown to improve liver biochemistry and survival. We report two patients with PBC who show a fall in serum alkaline phosphates levels whilst receiving tamoxifen therapy. Tamoxifen may exert this effect, which warrants further study, either via cholangiocyte estrogen receptors, inhibiting cholangiocyte proliferation and inducing apoptosis or by activating pregnane X receptor, analogous to the mode of action of UDCA.

Evaluation of the outcome of amniotic membrane transplantation for ocular surface reconstruction in symblepharon

AIMS

Symblepharon is a condition that can inflict serious morbidity on the affected patients. Our aim was to evaluate the efficacy of amniotic membrane transplantation in the surgical treatment of symblepharon by determining the rate of epithelization of the graft, the incidence of complications, and the rate of recurrence of cicatrization.

METHODS

In all, 20 eyes of 18 patients with symblepharon due to various causes and with varied indications for surgery underwent symblepharon excision and amniotic membrane transplantation (AMT).

RESULTS

We observed recurrence of symblepharon in eight out of the 20 eyes operated upon, but in two of these the cicatrization was focal in nature and did not afford any functional impairment to the patients. Four out of the six eyes that failed had preoperative severe dry eye, and four had undergone previous conjunctival surgery.

CONCLUSIONS

AMT appears to be a safe and effective procedure for the surgical treatment of symblepharon. We observed a 100% rate of epithelization of the graft with no significant postoperative complications and a 30% rate of cicatrization. Pre-existing dry eye and previous conjunctival surgery influence the success of the surgery and these eyes may need medical or surgical supplementation along with AMT to limit the amount of subconjunctival fibrosis for better surgical results.

Common psychiatric diseases and human genetic variation

OBJECTIVE

A better understanding of human genetic variation is important in assessing disease epidemiology and phenotypic variation, and may be critical in evaluating genetic aspects of common genetic diseases, such as schizophrenia, bipolar disease and Parkinson's. These diseases are particularly difficult to investigate as there are few peripheral markers, and although a genetic aetiology has long been suspected, robust findings have been hard to establish.

METHODS

Variations in alleles at 13 tri-nucleotide gene loci expressed in the brain and implicated in several neurodegenerative diseases, as well as certain other loci, were examined in the Indian population for comparison with other major ethnic groups.

RESULTS AND CONCLUSION

In the Indian population, the distribution of alleles at the Machado-Joseph disease locus was similar to the Western European pattern of distribution. Analysis of haplotypes at the locus for Huntington's disease suggested multiple origins, and possible effects of population admixture because of the recent history of the country. At other alleles of neuropsychiatric interest (dopamine receptor, serotonin receptor, serotonin transporter, alcohol dehydrogenase), allele frequencies in the Indian population differed from other populations. Interspecies comparison suggests a gradual expansion in repeat size, with the exception of the CLOCK gene, which displays a contraction of CAG repeat numbers. World-wide differences in disease phenotypes need to be explored, and an appreciation of their genetic basis may provide a window of opportunity for improving our knowledge of the underlying genetic mechanisms.

Loss of circadian rhythm of blood pressure following acute stroke

BACKGROUND

Epidemiology of acute stroke in developing countries differs from that in the developed world, for example, the age at stroke, risk factors, subtypes of stroke and prognosis. Hypertension remains a dominant risk factor and prognostic indicator in patients with stroke in all communities. The risk of stroke is directly related to elevations of blood pressure. A number of clinical studies have shown that the control of hypertension leads to a reduction in the incidence of stroke in a community. However there is still considerable controversy surrounds the changes in blood pressure in various subtypes of strokes and problem of management of elevated BP after stroke. We studied the circadian rhythm of blood pressure in patients following acute stroke.

METHODS

To study the circadian rhythm of blood pressure, fifty consecutive patients with an acute stroke who were admitted to medical emergency within 120 hours of onset were included in the study. After a detailed history and clinical examination, a continuous blood pressure monitor (Spacelab 90207) was attached on the side ipsilateral to intracranial lesion (unaffected arm). The blood pressure was recorded for 24 hours at 15 minutes interval during daytime (6.00 am-6.00 pm) and 20 minutes interval overnight (6 pm to 6 am).

RESULTS

Risk factors for stroke in 50 patients included hypertension in 31(62%), diabetes mellitus in 4 (8%), smoking in 13 (26%) and previous history of transient ischemic attack in 7 (14%) patients. Mean systolic pressure and diastolic pressure at admission were higher in patients with hemorrhagic stroke -29 patients (177 +/- 24 mmHg and 105 +/- 19 mmHg respectively) compared to patients with ischemic strokes-21 patients (150 +/- 36 mm Hg and 89 +/- 18 mm Hg respectively, p value <0.01 in both comparisons). The normal diurnal variation in blood pressure (night time dipping of more than 10%) was abolished in 44 (88%) of patients. Out of 44 nondippers, 29 patients showed reverse dipping i.e. rise of BP during night time compared to day time levels. None of the risk factors, clinical or laboratory variables, type of stroke or blood pressure changes differed significantly between these two groups.

CONCLUSIONS

Therefore, we showed a pathologically reduced or abolished circadian BP variation after stroke. Absence of normal dipping results in a higher 24 hour blood pressure load and may have more target organ damage than those with normal diurnal variation of blood pressure.

Genetics in epilepsy: transcultural perspectives

In the last two decades there have been many significant advances with regard to the genetics of human epilepsies. Knowledge of the mutations responsible for inherited human epilepsies not only will help in a better diagnosis and understanding of the mechanisms involved in epileptogenesis and their inheritance, but also will result in the development of better and safer antiepileptic drugs, discovery of novel therapeutic modalities, improved genetic counseling, and perhaps even prevention of epilepsies. The overall impact of these genetic discoveries across different populations and cultures will perhaps be beneficial to improving the lives of the millions affected by these diverse but common brain disorders.

Obstructive sleep apnoea: a case-control study

INTRODUCTION

Obstructive sleep apnoea (OSA), is characterized by loud snoring and excessive daytime sleepiness. Though the gold standard for diagnosis is overnight polysomnography (PSG), sleep questionnaires have also been used to diagnose this with good predictive value.

MATERIAL AND METHODS

A pre-designed proforma with clinical details, symptom-specific questions for diagnosis of OSA, and Epworth Sleepiness Scale (ESS) was administered to 20 patients presenting to the Sleep Disorder Clinic of our hospital and to 40 age and sex-matched relatives (control group). The students 't-test' and chi-square were used as the statistical tests.

RESULTS

There were 20 patients with a mean age of 41+/- 8 years, and 40 controls with a mean age of 41 +/- 6 years (P=>0.05). Seven had family history of snoring in the study group and 3 in the control group (P=0.02). Four had met with road traffic accidents in the study group and none in the control group (P=0.001). The body mass index (BMI) was 29.9 (SD 4.4) in the study group and 24.5 (SD3.5) in the controls (P=0.001). The mean ESS was 13.3 +/- 6 in the patients and 4.2+ 4 in the controls (P=0.001). A larger number of patients with OSA had hypertension: 5/20 vs. 3/40 (P=0.01).

CONCLUSION

Patients with OSA had significantly higher BMI and ESS score, and were more likely to have hypertension and road traffic accidents. Increased awareness of this entity is essential.

A study of nonepileptic seizures in an Indian population

OBJECTIVE

The goal of this study was to evaluate the background and the clinical profile of nonepileptic seizures (NESs) confirmed by short-term video encephalography (ST-VEEG) recording in an Indian population.

METHODS

Seventy-one patients with NESs were enrolled. A complete history was taken and the recorded event was reviewed to define the ictal events. Patients were divided into two groups, Group 1 with a paucity of movements and Group 2 with an excess of movement, and results were analyzed.

RESULTS

The mean age was 22.9 (9.6); there were 15 males (21.1%) and 56 females (78.9%). Twenty-four patients (33.8%) were receiving antiepileptic drugs. The majority of the patients (42, 59.1%) were students. All patients were amnesic for the event and were unresponsive during the event. The other characteristics were similar events in 98.6%, hyperventilation in 58 (81.7%). Forty-two patients (59.2%) were in Group 1 and 29 patients (40.8%) were in Group 2.

CONCLUSION

NES is a disease of the young and can affect the student or professional. A wrong diagnosis can result in inappropriate treatment. Awareness of this entity is critical to ensuring prompt diagnosis and early intervention.

Molecular analysis of Huntington's disease and linked polymorphisms in the Indian population

OBJECTIVES

To understand the population variation and haplotypes of Huntington's disease (HD) in India we have analysed CAG repeats at the HD locus together with closely linked polymorphisms in both HD patients and normal controls.

MATERIALS AND METHODS

The CAG repeat and linked polymorphisms were analysed in 30 Indian HD families together with 250 ethnically matched controls using fluorescent polymerase chain reaction (PCR) based size estimation.

RESULTS

CAG repeats at the HD locus in the normal population showed a mean size of 17.99 +/- 2.66 repeats (range nine to 33 repeats). The HD mutation in our families did not show any significant association with either the (CCG)7 or (CCG)10 allele while haplotype analysis suggested the over-representation of the 7-2-I (CCG-D4s127-Delta 2642 loci) haplotype in a subset of families.

CONCLUSION

The distribution of CAG repeats in the normal population suggests a higher prevalence of HD, closer to that seen in Western Europe. Haplotype analysis suggests the presence of a founder mutation in a subset of families and provides evidence for multiple and geographically distinct origins for the HD mutation in India.

Seizure worsening with topiramate amongst Indians with refractory epilepsy

In a prospective open label add-on study on 95 patients (age 1-63 years, mean 17.76 +/- 13.83 years) with seizures refractory to conventional antiepileptic drugs (AEDs) and other new AEDs, the addition of Topiramate (TPM) resulted in seizure worsening in 18 patients (19%) necessitating drug withdrawal over an average follow-up period of 4.94 +/- 1.69 months. Patients who had seizure worsening were older (P = 0.02), were more likely to have had a history of status epilepticus in the past (P = 0.03), were on three conventional AEDs (P = 0.027) or had tried one of the other new AEDs in the past with poor response (P = 0.04). Seven of 18 patients who had seizure worsening with TPM (7.4%) experienced initial seizure worsening, probably representing the subgroup with 'true' seizure worsening whilst 11 (11.6%) had initial improvement followed by 'apparent' seizure worsening. Initial seizure worsening was noted to be significantly more in females when compared with males who worsened after initial improvement (P = 0.05).

Hyperhomocysteinemia masquerading as pulmonary embolism

We describe a 30-year-old male who presented with acute onset of breathlessness, tachycardia, and palpitations associated with distension of jugular vein and clear lungs on physical examination. The chest X-ray was normal and ECG was showing S1Q3T3 and right ventricular strain pattern. His 2-D echocardiography was showing dilated right atrium, right ventricular dilatation and moderate pulmonary arterial hypertension. He was found to have thrombosis involving left side of deep venous system with normal superficial venous system (Doppler proved). All routine blood investigations for etiology of recurrent DVT were normal except serum homocyteine level, which was significantly raised. Megaloblastic anemia on peripheral smear and hyperhomocysteinemia prompted us to search for its cause, which was subsequently found to be vitamin B12 deficiency. Such an association of megaloblastic anemia due to vitamin B12 deficiency leading to hyperhomocysteinemia and subsequent thrombosis in left venous system presenting as acute pulmonary embolism has not been described earlier in the medical literature.

X-linked lissencephaly in an Indian family

Neuronal migration disorders are an important differential diagnosis to be considered in the evaluation of intractable epilepsy. Though the underlying causative factors which govern their development are many and varied, genetic factors have been found to be contributory in a few forms of these disorders. An X-linked association with lissencephaly has recently been discovered and there are a few families described till now with this entity.

Analgesic efficacy of intramuscular opioids versus epidural analgesia in labor

OBJECTIVES

To compare analgesic efficacy of intramuscular opioids: meperidine and tramadol with epidural analgesia.

METHODS

One hundred and twenty-eight term nulliparous women with singleton pregnancy and vertex presentation were randomized to receive either epidural (n=43), meperidine (n=39) or tramadol (n=44). A visual analog scale (VAS) was used to assess the severity of pain. The parameters analyzed were analgesic efficacy, effect on labor, other maternal side effects, perinatal outcome and maternal satisfaction.

RESULTS

Median VAS scores following first dose were 0 (0-5), 5 (3-8) and 5 (3-8) in epidural, meperidine and tramadol groups, respectively. Ninety percent of women rated analgesia as good to excellent in the epidural group as compared with 72% of women in the meperidine group and 65% in tramadol group. However, epidural caused a significant prolongation of first (P<0.05) and second (P<0.01) stage of labor with an increased number of operative deliveries (27% in the epidural, 7.6% in the meperidine, and 11.4% in the tramadol groups, P<0.05). In the epidural group 40% women had urinary retention and 16% had motor weakness, whereas sedation was the only side effect seen in the meperidine (41%) and tramadol groups (9%). Respiratory depression was noted among three neonates in the meperidine group, two in the tramadol group and none in the epidural group.

CONCLUSIONS

The analgesic efficacy and maternal satisfaction is better with epidural analgesia than with opioids. Analgesia provided by meperidine and tramadol is comparable and approximately 50% of women rated the analgesia as good. Meperidine is better in the second stage than tramadol. Hence in developing nations where availability of facilities is the main limiting factor, intramuscular opioids can be considered suitable alternatives.

Restless legs syndrome: diagnosis and treatment

AIM

To describe clinical, biochemical and electrophysiological profile in Indian patients with Restless Legs Syndrome.

MATERIAL AND METHODS

A total of 84 patients with sleep disorders were evaluated. Eight patients were diagnosed to have RLS. All underwent series of hematological, biochemical investigations and electrophysiological studies. Severity was assessed before and after specific treatment

RESULTS

Eight patients presenting with clinical features of RLS formed the study group. The mean age was 51.6 +/- 13.8 years. The male : female ratio was 7:1. Six cases were primary and two were of secondary type of RLS. Seven patients reported significant improvement in symptoms after treatment

CONCLUSION

RLS can be diagnosed purely on clinical criteria; and appropriate treatment results in significant relief. Thus, the recognition of this entity is essential.

Heavy metal pollution in various canals originating from river Yamuna in Haryana

Heavy metal pollution due to Fe, Ni, Pb, Cd, Co and Zn in the water of major canals originating from the river Yamuna in Haryana was studied. All these metals except Zn were found to be present in the Western Yamuna Canal (WYC) exceeding the maximum permissible limits. In the Sunder branch (SB), the heavy metal concentration was relatively more. Concentrations of the metals were, however, relatively less in the highly eutrophicated waters of Agra canal and Gurgaon canal as compared to that in WYC but Fe concentration were much higher. Except Zn and Ni the metal concentrations exceeded the standard permissible limits in these canals also.