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Biomedical subjects

E Lancaster

Publications and source records attributed to E Lancaster.

17 recordsLinked to original sources
PubMed2004

Case selection in macular relocation surgery for age related macular degeneration.

BACKGROUND: To date there has been no randomised controlled trial demonstrating the safety and efficacy of macular relocation surgery (MRS) for age related macular degeneration (AMD). Vision can be improved in some patients and made worse in others despite successful surgery or because of complications. PURPOSE: To determine which patients would benefit from MRS. METHODS: Twenty nine patients with exudative AMD took part in a prospective, non-comparative, interventional study. Macular relocation surgery involved phacoemulsification, vitrectomy, 360 degrees retinotomy, excision of choroidal neovascular membrane, and macular relocation using an infusion of 5-fluorouracil and low molecular weight heparin as adjuvant to prevent proliferative vitreoretinopathy. Patients underwent protocol refraction preoperatively and six-monthly postoperatively by designated optometrists. Preoperative fundus fluorescein angiograms were read by masked observers and the lesions were classified according to a set protocol. The main outcome measures were visual improvement, final vision of better than 20/400, reading speed, critical print size. Logistic and multiple stepwise linear regressions were used to identify independent factors which predicted the main outcomes. RESULTS: Preoperative visual acuity (20/120 or worse) and lesion type (predominantly classic or submacular haemorrhage) were significantly associated with visual improvement (coefficient of regression B = 26.8, p<0.001 and B = 14.9 with p = 0.045 respectively). There were no significant independent factors which predicted a final distance logMAR visual acuity of 1.3 (20/400) or any arbitrary definition of blindness. CONCLUSIONS: The study showed that it was possible to select cases that were more likely to experience an improvement in vision following MRS.

Aged↗
PubMed2001

Sodium currents in vagotomized primary afferent neurones of the rat.

1. Nodose ganglion neurones (NGNs) become less excitable following section of the vagus nerve. To determine the role of sodium currents (I(Na)) in these changes, standard patch-clamp recording techniques were used to measure I(Na) in rat NGNs maintained in vivo for 5-6 days following vagotomy, and then in vitro for 2-9 h. 2. Total I(Na) and I(Na) density in vagotomized NGNs were similar to control values. However, steady-state I(Na) inactivation in vagotomized NGNs was shifted -9 mV relative to control values (V(1/2), -74 +/- 2 vs. -65 +/- 2 mV, P < 0.01) and I(Na) activation was shifted by -7 mV (V(1/2), -21 +/- 2 vs. -14 +/- 2 mV, P < 0.006). I(Na) recovery from inactivation was also slower in vagotomized NGNs (fast time constant, 2.8 +/- 0.4 vs. 1.6 +/- 0.3 ms, P < 0.02). 3. The fraction of I(Na) resistant to 1 microM tetrodotoxin (TTX-R) was halved in vagotomized NGNs (21 +/- 8 vs. 56 +/- 8 % of total I(Na), P < 0.05). This change from TTX-R I(Na) to TTX-sensitive (TTX-S) I(Na) may explain altered I(Na) activation, inactivation and repriming in vagotomized NGNs. 4. The contribution of alterations in I(Na) to NGN firing patterns was assessed by measuring I(Na) evoked by a series of action potential (AP) waveforms. In general, control NGNs produced large, repetitive TTX-R I(Na) while vagotomized NGNs produced smaller TTX-S I(Na) that rapidly inactivated during AP discharge. We conclude that TTX-R I(Na) is important for sustained AP discharge in NGNs, and that its diminution underlies the decreased AP discharge of vagotomized NGNs.

Action Potentials↗
PubMed2001

Vagotomy decreases excitability in primary vagal afferent somata.

Standard patch-clamp and intracellular recording techniques were used to monitor membrane excitability changes in adult inferior vagal ganglion neurons (nodose ganglion neurons, NGNs) 5 days following section of the vagus nerve (vagotomy). NGNs were maintained in vivo for 5 days following vagotomy, and then in vitro for 2-9 h prior to recording. Vagotomy increased action potential (AP) threshold by over 200% (264 +/- 19 pA, mean +/- SE, n = 66) compared with control values (81 +/- 20 pA, n = 68; P < 0.001). The number of APs evoked by a 3 times threshold 750-ms depolarizing current decreased by >70% (from 8.3 to 2.3 APs, P < 0.001) and the number of APs evoked by a standardized series of (0.1-0.9 nA, 750 ms) depolarizing current steps decreased by over 80% (from 16.9 APs to 2.6 APs, P < 0.001) in vagotomized NGNs. Similar decreases in excitability were observed in vagotomized NGNs in intact ganglia in vitro studied with "sharp" microelectrode techniques. Baseline electrophysiological properties and changes following vagotomy were similar in right and left NGNs. A "sham" vagotomy procedure had no effect on NGN properties at 5 days, indicating that changes were due to severing the vagus nerve itself, not surrounding tissue damage. NGNs isolated after being maintained 17 h in vivo following vagotomy revealed no differences in excitability, suggesting that vagotomy-induced changes occur some time from 1-5 days after injury. Decreased excitability was still observed in NGNs isolated after 20-21 days in vivo following vagotomy. These data indicate that, in contrast to many primary sensory neurons that are thought to become hyperexcitable following section of their axons, NGNs undergo a marked decrease in electrical excitability following vagotomy.

Action Potentials↗
PubMed1999

Lack of normal pattern of cerebral asymmetry in familial schizophrenic patients and their relatives--The Maudsley Family Study.

Lack of the normal cerebral asymmetry has been reported in schizophrenia. We wished to test the hypothesis that this lack of the normal pattern of asymmetry is familial and that it can be found in both schizophrenic and non-schizophrenic family members. In particular, we wanted to know whether those relatives who appear to be transmitting liability to the illness also demonstrate the loss of normal asymmetry. We studied families with several members affected with schizophrenia. We carried out volumetric measurements of prefrontal, premotor, sensorimotor and occipitoparietal regions in each hemisphere using 3D reconstructed MRI images in 29 schizophrenic patients, 55 of their first degree relatives, and 39 unrelated control subjects on contiguous thin slices of the brain. Nine of the unaffected relatives appeared to be transmitting the liability for schizophrenia (e.g. the mother of a schizophrenic patient who, although not psychotic herself, had a schizophrenic parent or sibling). We termed them presumed obligate carriers and the remaining 46 relatives presumed non-obligate carriers. The healthy control subjects showed larger right than left prefrontal regions and larger left than right sensorimotor and occipitoparietal regions. The schizophrenic patients showed lack of this normal brain asymmetry in the prefrontal, sensorimotor and occipitoparietal cortical regions. The presumed obligate carriers were similar to the schizophrenic patients in exhibiting lack of asymmetries in these cortical regions, while the presumed non-obligate relatives showed lack of asymmetry only in the occipitoparietal region. There was no overall reduction in total or regional brain volumes among the groups. Our findings indicate that lack of the normal pattern of frontal and occipital asymmetry is a marker for genetic liability to schizophrenia in families multiply affected with schizophrenia.

Adult↗
PubMed1998

Site of opioid action in the human brain: mu and kappa agonists' subjective and cerebral blood flow effects.

OBJECTIVE: Humans experience the subjective effects of mu and kappa opioid agonists differently: mu agonists produce mainly euphoria, while kappa agonists are more likely to produce dysphoria. This study tested the hypothesis that these subjective effects would be associated with anatomically distinct changes in regional cerebral blood flow (CBF) relative to baseline as assessed with single photon emission computed tomography (SPECT). METHOD: Nine nondependent opioid abusers participated in the study. In the first phase of the study, the participants were acclimated to effects of the study drugs. In the second phase they underwent repeat challenges with the study drugs followed by an assessment of CBF with use of the SPECT tracer [99mTc]HMPAO. Medications tested were the prototypic mu agonist hydromorphone, the mixed agonist/antagonist butorphanol (which has a kappa agonist component of activity), and saline placebo. RESULTS: Subjective effects of the drugs were distinctly different. Hydromorphone produced increased ratings of "good effects," while butorphanol led to more "bad effects." Hydromorphone significantly increased regional CBF in the anterior cingulate cortex, both amygdalae, and the thalamus--all structures belonging to the limbic system. Butorphanol caused a less distinct picture of regional CBF increases, mainly in the area of both temporal lobes. CONCLUSIONS: This study demonstrates that opioids with different subjective effects also produce statistically significant patterns of change in regional CBF from baseline, and the regions of statistical significance appear in different brain regions. In addition, these results demonstrate the applicability of SPECT functional neuroimaging in the study of medications with potential abuse liability.

Amygdala↗
PubMed1998

Brain changes in schizophrenia. Volumetric MRI study of families multiply affected with schizophrenia--the Maudsley Family Study 5.

BACKGROUND: Structural brain abnormalities have been reported in schizophrenia. We tested the hypothesis that these abnormalities represented a marker for the genetic liability to schizophrenia in a sample of people with schizophrenia and their relatives from families multiply affected with the disorder. METHOD: We compared 31 people with schizophrenia, 57 relatives and 39 unrelated control subjects. Volumetric measurement of brain structures was carried out using stereological principles from three-dimensional reconstructed magnetic resonance images. RESULTS: Subjects with schizophrenia had larger lateral ventricles than their relatives and the normal control subjects. Relatives who were 'presumed obligate carriers' had larger left lateral ventricles than other relatives and the control subjects. Subjects with schizophrenia showed smaller whole brain and cerebellar volumes and larger lateral ventricles than their age- and gender-matched unaffected siblings. CONCLUSIONS: In families multiply affected with schizophrenia lateral ventricular enlargement distinguishes people with schizophrenia and presumed obligate carriers from other relatives and unrelated control subjects. These changes may be a marker for a genetic liability to schizophrenia.

Adult↗
PubMed1997

Distribution and activation of intracellular Ca2+ stores in cultured olfactory bulb neurons.

The presence and distribution of intracellular Ca2+ release pathways in olfactory bulb neurons were studied in dissociated cell cultures. Histochemical techniques and imaging of Ca2+ fluxes were used to identify two major intracellular Ca2+ release mechanisms: inositol 1, 4,5-triphosphate receptor (IP3R)-mediated release, and ryanodine receptor-mediated release. Cultured neurons were identified by immunocytochemistry for the neuron-specificmarker beta-tubulin III. Morphometric analyses and immunocytochemistry for glutamic acid-decarboxylase revealed a heterogeneous population of cultured neurons with phenotypes corresponding to both projection (mitral/tufted) and intrinsic (periglomerular/granule) neurons of the in vivo olfactory bulb. Immunocytochemistry for the IP3R, and labeling with fluorescent-tagged ryanodine, revealed that, irrespective of cell type, almost all cultured neurons express IP3R and ryanodine binding sites in both somata and dendrites. Functional imaging revealed that intracellular Ca2+ fluxes can be generated in the absence of external Ca2+, using agonists specific to each of the intracellular release pathways. Local pressure application of glutamate or quisqualate evoked Ca2+ fluxes in both somata and dendrites in nominally Ca2+ free extracellular solutions, suggesting the presence of IP3-dependent Ca2+ release. These fluxes were blocked by preincubation with thapsigargin and persisted in the presence of the glutamate receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione. Local application of caffeine, a ryanodine receptor agonist, also evoked intracellular Ca2+ fluxes in the absence of extracellular Ca2+. These Ca2+ fluxes were suppressed by preincubation with ryanodine. In all neurons, both IP3- and ryanodine-dependent release pathways coexisted, suggesting that they interact to modulate intracellular Ca2+ concentrations.

Animals↗
PubMed1995

TB exposure: are you prepared?

1. The elderly have the highest case rates for TB disease. 2. Residents need to be screened for TB infection on admission with a Mantoux skin test. 3. Employees need to be screened for TB by the Mantoux skin test on hire and annually. 4. A chest x-ray is not adequate to screen for TB infection.

Humans↗
PubMed1993

Tuberculosis comeback: impact on long-term care facilities.

1. The number of tuberculosis (TB) cases in the United States has ceased to decline and is rising in some areas of the country. This means that the likelihood of having a long-term care patient with TB is greater. 2. To handle patients with TB, the epidemiology, transmission, pathogenesis, infectiousness, and treatment of tuberculosis must be understood. 3. The CDC has broken down the prevention and control activities into four categories: surveillance, containment, assessment, and education. Education is an integral part of the whole program. The education of both staff and patients should begin with an assessment of their knowledge of TB so that old, erroneous beliefs can be corrected and current knowledge imparted. Only then will we be able to improve understanding and cooperation, and ultimately ensure success in our TB control efforts.

Antitubercular Agents↗
PubMed1991

Tuberculosis in the OR.

1. The likelihood of a patient having tuberculosis is increasing. Tuberculosis crosses all levels of our society, but is not evenly distributed. 2. Tuberculosis is generally spread via airborne routes in "droplet nuclei." Rarely, transmission can occur by direct inoculation via skin puncture with a contaminated object. 3. Persons who have active disease may or may not be infectious, depending on many factors.

Humans↗
PubMedDate not supplied

Expression of endogenous lectins (galectins, receptors for ABH-epitopes) and the MIB-1 antigen in esophageal carcinomas and their syntactic structure analysis in relation to post-surgical tumor stage and lymph node involvement.

Squamous cell carcinomas of the esophagus, a disease with poor prognosis, are especially frequent in China and South Africa. To initiate the study of endogenous lectins in this tumor class we employed synthetic neoglycoconjugates and focused on galectins as markers. Histological sections of 43 cases of esophageal carcinomas were analyzed with labeled galectins-1 and -3 and their specific antibodies, neoglycoconjugates exposing chemically prepared histo-blood group A-, B- and H-trisaccharides and the antibody MIB-1 (Ki-67). Features of structural and numerical staining intensities determined quantitatively were correlated to clinical data sets of pTN stages, sex and age of patients. Low tumor stages (pT1/T2) were seen in 10/43 cases (23%) and 65% of the carcinomas surgically treated lacked notable lymph node involvement (pN0). The women were younger than the men (47 years versus 54 years). The proliferation activity of the tumor cells was high and amounted to 75% at average. The presence of galectin-1 and the structural entropy of distribution of staining with carrier-immobilized A-trisaccharide were associated with pN stages. These initial data indicate that distinct glycohistochemical features appear to have prognostic significance in this tumor class, adding to the emerging significance of this marker class in lung cancer.

ABO Blood-Group System↗
PubMedDate not supplied

Tuberculosis comeback: what you need to know.

1. The number of tuberculosis (TB) cases in the United States has ceased to decline and is rising in some areas of the country. This means that the likelihood of caring for a patient with TB is greater. 2. To handle patients with TB, the epidemiology, transmission, pathogenesis, infectiousness, and treatment of tuberculosis must be understood. 3. TB should be considered in any patient who has a persistent cough or other general symptoms of weight loss, fever, anorexia, and night sweats.

Cross Infection↗
PubMedDate not supplied

Hepatic siderosis, fibrosis and cirrhosis: the association with hepatocellular carcinoma in high-risk population.

Iron overload has been shown to impair the immune response of the liver, and induce hepatic fibrosis and cirrhosis. Opinions differ concerning the relative risk of developing hepatocellular carcinoma (HCC) in siderotic patients as compared with patients with hepatic fibrosis and cirrhosis and the possible mechanism of liver carcinogenesis in genetic hemochromatosis is still unknown. The purpose of this study is to assess hepatic iron overload, fibrosis and cirrhosis in liver tissue adjacent to hepatocellular carcinoma and in liver tissue of controls in population at risk for hepatocellular carcinoma. Liver tissue was available for examination in 147 biopsies with HCC collected in South Africa. As controls we used liver samples from 211 age and sex matched Africans who died in accidents. Tissue samples were processed routinely, stained with H and E, Sweet's reticulin, Masson's trichrome for fibrous tissue, Prussian blue for iron stain and immunohistochemically for HBsAg. Iron content was assessed with the method described by Brissot. Iron overload was detected in 42.1% of cancerous livers and in 43.7% of livers from controls. The presence of siderosis and iron content gradually increased with the age of studied similarly in cases and in controls. Cirrhosis was present in 32% of cancerous livers and was associated with iron overload in 13%. No cirrhosis and 6% of mild periportal fibrosis not related with siderosis was observed in controls. HBsAg was stainable in 80% of cancerous livers of patients below 25 years of age and in 40% of patients over 35 years. HBsAg in controls was positive in 9%. No relationship of HBsAg and amount of stainable iron in cancerous and livers of controls was found. In conclusion, African siderosis can not play important role in the etiopathogenesis of HCC.

Adult↗
PubMedDate not supplied

Proliferative activity of normal and neoplastic colonic mucosa in population groups with high and low risk for colorectal carcinoma.

Europeans have a high incidence of colorectal cancer in comparison to Africans. Lack of detectable sequence adenoma-colorectal carcinoma in Africans may suggest the development of adenocarcinoma is de novo. The aim of this study is to assess colonic mucosal proliferative activity in various pathological conditions of diverse population groups. Materials included routinely processed tissue specimens from consecutively resected well- and moderately differentiated colorectal adenocarcinomas from 32 rural Africans (South Africa) and 27 urban Europeans (Poland) and from apparently normal rectal mucous membrane from the age and sex matched each population group (28 and 25 samples respectively). In addition, 32 resected adenomatous polyps were examined in Europeans as well. The MIB 1 monoclonal antibody was used to assay the expression of Ki67 antigen in routinely processed tissue specimens. Proliferative activity in colonic carcinomas was scored by the percentage of positively stained cells. Labelling indices were estimated in 5 crypt compartments in apparently normal colonic mucosa adjacent and distant to the tumour, in mucosal samples of controls from both population groups and in adenomatous polyps from Europeans. The mean age of African patients with adenocarcinoma was markedly lower than in European counterparts (48.6 yrs vs. 66.4 yrs). The overall proliferative activity in cancerous tumours of Africans was higher than in Europeans. The labelling indices were lower in all compartments in normal colonic mucosa in Africans. Overall increase of the labelling indices in adjacent and distant to the tumour mucosa noted when compared to the mucosa of healthy individuals. No such differences were detected between indices in the mucosa adjacent and the mucosa distant to the tumour. Proliferative activity in the mucosa adjacent to adenoma was also higher than in normal mucosa from healthy individuals. Adenomas with marked dysplasia showed higher and diffuse proliferative activity, when regular adenomas shown superficial labelling only. Relatively young age, lack of detectable evidence of adenoma-carcinoma sequence and low proliferative activity in all compartments of mucosa from healthy individuals indicate different etiopathogenesis of colorectal carcinoma in rural Africans.

Adenocarcinoma↗