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Biomedical subjects

S Christopher

Publications and source records attributed to S Christopher.

At least 19 recordsLinked to original sources
PubMed2006

Blind placements of peripherally inserted antecubital central catheters: initial catheter tip position in relation to carina.

BACKGROUND: We investigated how often blind placement of peripherally inserted central catheters (PICCs) through the antecubital veins results in a correct tip location in relation to carina and evaluated the inter-observer agreement in locating the tip of PICCs in plain radiography with digital imaging. METHODS: In this study, 202 suitable chest radiographs with PICCs out of 803 patients were identified. An initial audit on the tip of these catheters in relation to carina was done by a consultant anaesthetist and was recorded as the first observer. The same sets of CXRs were examined by a consultant radiologist and the tips were identified and recorded as the second observer. Inter-observer agreement was assessed. RESULTS: In 75 of 202 (37%), PICCs had a central tip location in relation to the carina. Fifty-five of 131 (42%) right-sided catheters had a central location compared with 20 of 71 (28%) of the left-sided catheters. The tip position for right-sided catheters was most frequently centrally located whereas the tip for left-sided catheters was most commonly positioned in the ipsilateral innominate vein. There was excellent agreement between the observers in reporting the tip of PICCs at all positions (kappa=0.87) including central locations (kappa=0.83). CONCLUSIONS: Right antecubital PICCs are more likely to be placed in the central location in relation to the carina. PICCs inserted through the left antecubital veins need to be pushed further down to aim for a central location. Inter-observer variability in identifying the tip of PICCs is least with the introduction of digital imaging.

Catheterization, Central Venous↗
PubMed2001

Myosin ATPase in young and old mammalian myocardium: responses to exercise in cold and thermo neutral environment.

Resting levels of blood lactate (La) were significantly lower at 35 degrees C than at 25 degrees C in the trained (Tr) rats while untrained (UTr) rats maintained higher levels. Extent of decrease in blood glucose (Glu) in Tr rats was lower in cold (C) than in thermo neutral (N) water in young but not in old. Training in C had no impact on young right and left ventricles (RV and LV). UTr old rats showed loss in LV Glu at both the temperatures. Old trainees had reduced RV Glu in C while no change was observed at N. Substrate changes were concomitant with altered myosin ATPase activity. Young ventricles showed higher ATPase activity in LV than in RV, and training in C evoked elevations in RV enzyme. The results suggest that training may enhance the functional and biochemical activity in terms of higher myosin ATPase activity in N, as against a C environment, and the effect is better pronounced in LV. Anaerobic condition is felt more in C as seen through elevated blood La.

Animals↗
PubMed2000

Rapid purification of protein complexes from mammalian cells.

The evaluation of the protein binding partner(s) of biologically important proteins is currently an area of intense research, especially since the development of the yeast two-hybrid assay. However, not all protein-protein interactions uncovered by this assay are biologically relevant and another confirmatory assay must be performed. Ideally, this assay should be rapid, versatile and performed under conditions which mimic the 'normal' physiological state as closely as possible. Towards this goal, we have constructed two eukaryotic expression vectors that facilitate the purification of a protein of interest, along with any associated proteins, from mammalian cells. These vectors incorporate the following features: (i) a tetracycline-responsive promoter so that the level of protein production can be regulated; (ii) an N-terminal glutathione S-transferase tag or a triple repeat of the HA1 epitope, to facilitate purification of the protein either by glutathione affinity chromatography or immunoprecipitation, respectively, followed by a multiple cloning site; (iii) the gene for the enhanced green fluorescent protein (for detection of the presence of the fusion protein and subcellular localization); (iv) a puromycin marker for the selection of stable transformants; (v) a truncated EBNA protein and oriP sequence for episomal replication of the vector. These latter two features permit expansion of small cultures of transfected cells under puromycin selection, thereby increasing the amount of tagged protein that can be purified. We show that these vectors can be used to direct the doxycycline-inducible expression of tagged proteins and to recover tagged CIP1-p21 protein complexes from HeLa cells. Furthermore, we show that these tagged p21-purified complexes contain both cyclin A and Cdk2, which are known to interact with p21, but not beta-actin.

Animals↗
PubMed1997

Low-grade gliomas of chronic epilepsy: a distinct clinical and pathological entity.

The authors present a summary of their recent experience regarding the management of patients with a variety of low-grade gliomas found during the evaluation for chronic epilepsy. These tumors are notable because the long-term patient outcome in this population is significantly better than the anticipated results of patients with the same tumors who do not have chronic epilepsy. Based on the long history of preoperative seizures (median 14 years), the frequent cortical location, and the absence of tumor recurrence or anaplastic transformation and the lack of mortality in this population, low-grade gliomas of chronic epilepsy appear to define a specific pathological entity that separates them from other histologically similar low-grade gliomas. Low-grade gliomas of chronic epilepsy also are notable for the absence of morphological features that characterize with dysembryoplastic neuroepithelial tumors (DNTs). Our evidence suggests that low-grade gliomas of chronic epilepsy should be recognized as a distinct pathological entity.

Adolescent↗
PubMed1997

Low-grade gliomas: introduction and overview.

This issue of the Journal of Neuro-Oncology is devoted to recent investigations of low-grade gliomas. The purpose of this issue is not to debate the relative merits and liabilities of different management strategies for low-grade gliomas, but to present new data concerning novel and innovative approaches to evaluating these lesions. The common theme of many of these reports represents a departure from grading systems that primarily depend on a morphology-based analysis from light microscopy to classify these tumors. The purpose of this review is to present the reasoning behind the selection of authors for this issue of the Journal of Neuro-Oncology and to provide a format for presentation of new ideas concerning these interesting tumors. It is clear that standard classification systems that address only the morphological characteristics of tumor cells can not adequately represent the wide variation in biological activity that is found with these lesions. It is hoped that these articles will stimulate further interest and research into low-grade gliomas that will one day lead to more effective therapy.

Adult↗
PubMed1996

Variations in the natural history and survival of patients with supratentorial low-grade astrocytomas.

Data from 55 consecutive patients with low-grade astrocytomas treated between 1982 and 1990 were analyzed to determine specific outcome factors, including time to recurrence, incidence of anaplastic transformation, and survival. Gender, type of symptoms, contrast enhancement, and timing of radiation therapy were not significant in determining outcome. Patients who had symptoms for > 2 years and underwent gross-total resection of the tumor, with age as a continuous variable, were associated with significantly longer time to recurrence and survival. Within the population of patients with low-grade astrocytomas, patients with chronic epilepsy clearly had the best prognoses. There were no tumor recurrences or deaths in 27 patients with chronic epilepsy, regardless of the extent of surgery and without the use of radiotherapy. Ten-year survival was 100% for 31 patients who underwent gross-total tumor resection, regardless of the length of preoperative symptoms. Immediate postoperative radiotherapy did not prolong the time to recurrence, reduce the incidence of transition to more malignant tumors at recurrence, or increase the length of survival when compared with delayed radiotherapy. Because recurrence with a high-grade lesion caused 92% of the mortality in our series, the benefit in patients who underwent aggressive surgery seems to result from a significant decrease in the risk of recurrence when compared with patients who underwent anything less than gross-total resection. Our data also suggest that variability in the natural history of low-grade astrocytomas has a strong influence in determining survival and that tumors associated with chronic epilepsy are much less likely to become more malignant over time.

Adult↗
PubMed1995

Prevalence and presentation of hepatitis C related chronic liver disease in southern India.

To determine the importance of hepatitis C virus (HCV) infection in the aetiology of chronic liver disease in southern India, the prevalence of HCV antibodies and HBV markers was estimated in 100 patients with chronic liver disease and in 56 patients with a variety of other gastrointestinal and liver diseases who served as controls. HCV antibody was measured by a second-generation ELISA. HBsAg, anti-HBc, anti-HBs and anti-D were also estimated. HCV antibodies were detected in 26/100 patients with chronic liver disease compared to 0/56 controls. HBV markers were present in 72 of 100 patients with chronic liver disease compared to 21/56 (37.5%) controls. Anti-D was noted in 4/100 patients with chronic liver disease and in none of the controls. Many patients had serological evidence of both B and C infection; 73% of those with anti-HCV also tested positive for HBV markers. HCV related disease presented at a median age of 60 years compared to HBV related disease which presented at a median age of 40. There was no significant difference between HCV and HBV positive patients in symptomatology, but encephalopathy was uncommon and cirrhosis the usual finding at histology in HCV positive individuals, while chronic active hepatitis was found in 30% of biopsied HBV related disease. HCV is a significant cause of chronic liver disease in this geographic region, although HBV infection continues to account for the largest proportion of cases.

Adolescent↗
PubMed1983

Adult polio-like syndrome following Enterovirus 70 conjunctivitis (natural history of the disease).

During the Indian EV 70 conjunctivitis epidemic in 1981, 79 patients with neurological complications were evaluated by clinical, electrophysiological, histopathological and virological studies. The disease was heralded by an attack of conjunctivitis and was followed, after a variable latent period, by a pre-paralytic, paralytic, and post-paralytic stage of slow recovery. The above events occurred in an orderly sequence. The paralysis affected the cranial nerves, limbs or both. The clinical course closely simulated poliomyelitis, without any evidence of radiculopathy or myelopathy. Cranial nerve palsies were seen in approximately half of the patients. The electrophysiological and histologicl studies pointed towards the affection of anterior horn cells. The raised neutralizing antibody titres to Enterovirus 70, confirmed the aetiology of the disease. On the available data, we believe that this nosological entity should be considered under the general title of "polio-like syndrome" following EV 70 conjunctivitis. On account of two epidemics in 1971 and 1981 with unfavourable prognosis and high resultant disability, and because of lack of specific therapy, it has become imperative to develop, as a top priority, a vaccine for immunization.

Adult↗
PubMed1982

An epidemic of acute hemorrhagic conjunctivitis due to coxsackievirus A24.

An epidemic of acute hemorrhagic conjunctivitis in 416 (10.8%) of 3,830 staff and students of the Christian Medical College and Hospital in Vellore, India, during September-December 1979 was studied. Virus was isolated in cultures of HeLa cells from 171 of the 249 persons cultured. Most of the viral isolates were identified as an antigenic variant of coxsackievirus A24. Success in isolating the virus from conjunctival swabs was inversely proportional to the time elapsed between the onset of illness and the time the specimens were collected. In general, titers of antibody to coxsackievirus A24 were low or undetectable. Three persons had subconjunctival hemorrhage with no other symptoms, and virologic evidence of infection with coxsackievirus A24 was obtained in two of them.

Acute Disease↗
PubMed1977

Lack of relationship between viruses and human diabetes mellitus.

Antibodies titres against Coxsackie-B (CB) and mumps virus (MV) were determined in 180 normal subjects and two groups of diabetics, 236 with diabetes of recent onset (DRO) and 108 with diabetes of long duration (DLD). Positive antibody titres to these viruses were found more frequently in controls than in diabetics. In fact, the percentage of positive titres was significantly less than in controls in several instances particularly in juvenile onset diabetes of long duration. These data suggest that CB and MV are not causally related to human diabetes mellitus.

Adolescent↗
PubMed1975

Oral polio vaccination of children in the tropics. III. Intercurrent enterovirus infections, vaccine virus take and antibody response.

The effect of intercurrent enterovirus infections on host responses to oral polio vaccine (OPV) was studied in groups of infants and children who were without antibodies to one, two or three serotypes of poliovirus. The prevalence of enterovirus infections as detected in fecal specimens collected at weekly intervals and inoculated in primary monkey kidney cell culture, HEp 2 cells and newborn mice ranged between 60 and 70 per cent. The presence of such infections at the time of, 1 week prior to, or during the 3 weeks prior to the administration of OPV did not appear to inhibit either vaccine virus take or antibody response. However, in both the infected and uninfected children the rates of vaccine virus take and seroconversion were found to be considerably lower than those reported from several temperate climate countries.

Child, Preschool↗