Biomedical subjects

C A Scott

Publications and source records attributed to C A Scott.

At least 19 recordsLinked to original sources

PubMed2001

Serum iron indices as a measure of iron deposits in chronic hepatitis C.

Serum iron indices are believed to be elevated in patients with hepatitis C virus (HCV) infection in connection to the presence of hepatic inflammation, though this hypothesis has never been formally tested. We studied 69 consecutive, unselected anti HCV antibody positive patients, aged 14 to 70 years. Iron, transferrin saturation and ferritin were measured in fasting serum samples. Histologically detectable iron (HDI) as well as histologic grading and staging were estimated semiquantitatively in liver biopsy samples. The median values for serum iron, transferrin saturation and serum ferritin were 24 micromol/l (range, 8-61), 29 percent (range, 6-77) and 170 microg/l (range, 1-954), respectively. At univariate analysis, all three serum iron indices were positively correlated with grading and staging scores, as well as with HDI in the liver; only serum iron was positively correlated with transaminases. At multivariate analysis, independent associations were found between serum iron and the grading score; ferritin and sinusoidal and portal HDI; transferrin saturation and total hepatic HDI. In conclusion, in hepatitis C, serum iron reflects the degree of current hepatic inflammation and necrosis, whereas the extent of progressive deposition of iron in sites of fibrosis is best reflected by serum ferritin. Transferrin saturation is the best predictor of the status of hepatic iron deposits.

Adolescent↗

PubMed2001

Transurethral radiofrequency thermal ablation of prostatic tissue: a feasibility study in humans.

OBJECTIVES: To evaluate the feasibility and efficacy of ablating prostatic tissue by inducing thermal lesions using radiofrequency (RF) energy delivered transurethrally through electrodes mounted on a Foley-like catheter. METHODS: Twenty male patients, candidates for radical cystoprostatectomy to treat bladder carcinoma, underwent RF prostate ablation 1 to 8 days before surgery (mean 2.8). Stainless steel, internally cooled, 2-cm-long electrodes mounted on a Foley-like catheter were used to deliver RF energy to the prostatic tissue. Semicircular electrodes were used in 10 patients (group A) and circular electrodes were used in the remaining 10 patients (group B). The urethral, rectal, and prostatic tissue temperatures were recorded. Histologic step sections were performed on whole mounts of the prostates to define the volume of the thermal lesions. RESULTS: The mean RF energy delivered was 36.5 kJ (range 26.4 to 53.1) in group A and 82.3 kJ (range 38 to 149) in group B. The intraprostatic temperatures were between 44 degrees C and 80 degrees C in group A and between 60 degrees C and 119 degrees C in group B. The urethral and rectal temperatures never exceeded 42 degrees C. No major complications occurred. After the RF procedure, 5 patients who received more than 75 kJ of energy could not void and required catheterization. The mean prostate volume was 11.54 cm(3) for group A and 24.02 cm(3) for group B. The mean volumes of the thermal lesions and their relative percentages in relation to the whole prostate in groups A and B were, respectively, 1.69 cm(3) and 15% and 6.91 cm(3) and 29% (P = 0.049). Analysis of variance showed a significant correlation between the thermal lesion volume and the energy delivered, regardless of the electrode shape (P = 0.001). CONCLUSIONS: Satisfactory thermal ablation of prostatic tissue can be achieved using RF electrodes mounted on a Foley-like catheter. The procedure is effective, simple, and safe and, therefore, can be used in pilot clinical studies on patients with benign prostatic hyperplasia.

Aged↗

PubMed2001

The midline thalamus: alterations and a potential role in limbic epilepsy.

PURPOSE: In limbic or mesial temporal lobe epilepsy, much attention has been given to specific regions or cell populations (e.g., the hippocampus or dentate granule cells). Epileptic seizures may involve broader changes in neural circuits, and evidence suggests that subcortical regions may play a role. In this study we examined the midline thalamic regions for involvement in limbic seizures, changes in anatomy and physiology, and the potential role for this region in limbic seizures and epilepsy. METHODS: Using two rat models for limbic epilepsy (hippocampal kindled and chronic spontaneous limbic epilepsy) we examined the midline thalamus for evidence of involvement in seizure activity, alterations in structure, changes in the basic in vitro physiology of the thalamic neurons. We also explored how this region may influence limbic seizures. RESULTS: The midline thalamus was consistently involved with seizure activity from the onset, and there was significant neuronal loss in the medial dorsal and reuniens/rhomboid nuclei. In addition, thalamic neurons had changes in synaptically mediated and voltage-gated responses. Infusion of lidocaine into the midline thalamus significantly shortened afterdischarge duration. CONCLUSIONS: These observations suggest that this thalamic region is part of the neural circuitry of limbic epilepsy and may play a significant role in seizure modulation. Local neuronal changes can enhance the excitability of the thalamolimbic circuits.

Anatomy, Cross-Sectional↗

PubMed2001

Ectoparasites of the island fox on Santa Cruz Island.

The ectoparasite fauna for island foxes (Urocyon littoralis) on Santa Cruz Island (California, USA) in April (wet season) and September (dry season) 1998 was evaluated. Three taxa of ectoparasites were identified. These were fleas (Pulex irritans), lice (Neotrichodectes mephitidis), and ticks (Ixodes pacificus). Ectoparasite abundances varied seasonally. Typical of insular endemic species, island foxes may be especially vulnerable to the introduction of novel disease organisms and their vectors.

Animal Diseases↗

PubMed2001

Spatio-temporal imaging of focal interictal epileptiform activity using EEG-triggered functional MRI.

EEG-triggered, blood oxygen level-dependent functional MRI (BOLD-fMRI) was used in 24 patients with localization-related epilepsy and frequent interictal epileptiform discharges (spikes) to identify those brain areas involved in generating the spikes, and to study the evolution of the BOLD signal change over time. The location of the fMRI activation was compared with the scalp EEG spike focus and the structural MR abnormality. Twelve patients (50%) had an fMRI activation concordant with the EEG focus and structural brain abnormalities where present (n = 7). In 2 other patients, the fMRI activation was non-concordant with electroclinical findings. The remaining 10 patients (41.7%) showed no significant fMRI activation. These patients had significantly lower mean spike amplitudes compared to those with positive fMRI results (p = 0.03). The time course of the BOLD response was studied in 3 patients and this revealed a maximum signal change 1.5 to 7.5 sec after the spike. In conclusion, EEG-triggered fMRI can directly identify the generators of interictal epileptiform activity, with high spatial resolution, in selected patients with frequent spikes. The superior spatial resolution obtainable through EEG-triggered fMRI may provide an additional non-invasive tool in the presurgical evaluation of patients with intractable focal seizures.

Action Potentials↗

PubMed2000

The I-Ag7 MHC class II molecule linked to murine diabetes is a promiscuous peptide binder.

Susceptibility to insulin-dependent diabetes mellitus is linked to MHC class II genes. The only MHC class II molecule expressed by nonobese diabetic (NOD) mice, I-Ag7, shares a common alpha-chain with I-Ad but has a peculiar beta-chain. As with most beta-chain alleles linked to diabetes susceptibility, I-Ag7 contains a nonaspartic residue at position beta57. We have produced large amounts of empty I-Ag7 molecules using a fly expression system to characterize its biochemical properties and peptide binding by phage-displayed peptide libraries. The identification of a specific binding peptide derived from glutamic acid decarboxylase (GAD65) has allowed us to crystallize and obtain the three-dimensional structure of I-Ag7. Structural information was critical in evaluating the binding studies. I-Ag7, like I-Ad, appears to be very promiscuous in terms of peptide binding. Their binding motifs are degenerate and contain small and/or small hydrophobic residues at P4 and P6 of the peptide, a motif frequently found in most globular proteins. The degree of promiscuity is increased for I-Ag7 over I-Ad as a consequence of a larger P9 pocket that can specifically accommodate negatively charged residues, as well as possibly residues with bulky side chains. So, although I-Ad and I-Ag7 are structurally closely related, stable molecules and good peptide binders, they differ functionally in their ability to bind significantly different peptide repertoires that are heavily influenced by the presence or the absence of a negatively charged residue at position 57 of the beta-chain. These characteristics link I-Ag7 with autoimmune diseases, such as insulin-dependent diabetes mellitus.

Amino Acid Motifs↗

PubMed2000

Evidence for elevated telomerase activity in small cell carcinoma of the bladder.

Telomerase activity was found to be elevated using a quantitative assay on snap-frozen protein extracts of exfoliated cells in urine and bladder washings and tumor tissue obtained from a male patient with small cell carcinoma of the bladder. To the best of our knowledge, this is the first demonstration of elevated values of telomerase activity in genitourinary small cell carcinoma and is in keeping with the findings in primary lung locations.

Aged↗

PubMed2000

Ureteral obstruction after kidney transplantation secondary to bone metaplasia.

We report a case of ureteral obstruction after kidney transplantation caused by localized bone metaplasia in the donor ureter. Surgical treatment consisted of removal of the involved ureteral segment, which was located 3 cm above the bladder and creation of a spatulated end-to-end anastomosis. Although bone metaplasia has been observed in the ureteral wall of some animal species secondary to experimental ischemia and microtrauma, it is exceedingly rare in humans and has never before been documented after kidney transplantation.

Adult↗

PubMed2000

A structural framework for deciphering the link between I-Ag7 and autoimmune diabetes.

Susceptibility to murine and human insulin-dependent diabetes mellitus correlates strongly with major histocompatibility complex (MHC) class II I-A or HLA-DQ alleles that lack an aspartic acid at position beta57. I-Ag7 lacks this aspartate and is the only class II allele expressed by the nonobese diabetic mouse. The crystal structure of I-Ag7 was determined at 2.6 angstrom resolution as a complex with a high-affinity peptide from the autoantigen glutamic acid decarboxylase (GAD) 65. I-Ag7 has a substantially wider peptide-binding groove around beta57, which accounts for distinct peptide preferences compared with other MHC class II alleles. Loss of Asp(beta57) leads to an oxyanion hole in I-Ag7 that can be filled by peptide carboxyl residues or, perhaps, through interaction with the T cell receptor.

Alleles↗

PubMed2000

Two rare lumbar tumours with unusual MRI characteristics.

We present two rare lumbar lesions with similar MRI features: high signal on T1-weighted and proton density images and low signal on T2-weighted images; a melanotic schwannoma, and a giant-cell tumour-like lesion. Melanin in the first case and haemosiderin and metahaemoglobin in the second were responsible for the MRI characteristics.

Aged↗

PubMed2000

Aberrant neuronal physiology in the basal nucleus of the amygdala in a model of chronic limbic epilepsy.

Limbic epilepsy is a chronic condition associated with a broad zone of seizure onset and pathology. Studies have focused mainly on the hippocampus, but there are indications that changes occur in other regions of the limbic system. This study used in vitro intracellular recording and histology to examine alterations to the physiology and anatomy of the basal nucleus of the amygdala in a rat model of chronic limbic epilepsy characterized by spontaneously recurring seizures. Epileptic pyramidal neuron responses evoked by stria terminalis stimulation revealed hyperexcitability characterized by multiple action potential bursts and no evident inhibitory potentials. In contrast, no hyperexcitability was observed in amygdalar neurons from kindled (included as a control for seizure activity) or control rats. Blockade of ionotropic glutamate receptors unmasked inhibitory postsynaptic potentials in epileptic pyramidal neurons. Control, kindled and epileptic inhibitory potentials were predominantly biphasic, with fast and slow components, but a few cells exhibited only the fast component (2/12 in controls, 0/3 in kindled, 3/10 in epileptic). Epileptic fast inhibitory potentials had a more rapid onset and shorter duration than control and kindled. Approximately 40% of control neurons exhibited spontaneous inhibitory potentials; no spontaneous inhibitory potentials were observed in neurons from kindled or epileptic rats. A preliminary histological examination revealed no gross alterations in the basal amygdala from epileptic animals. These results extend previous findings from this laboratory that hyperexcitability is found in multiple epileptic limbic regions and may be secondary to multiple alterations in excitatory and inhibitory efficacy. Because there were no differences between control and kindled animals, the changes observed in the epileptic animals are unlikely to be secondary to recurrent seizures.

Action Potentials↗

PubMed2000

Fixation-off sensitivity as a model of continuous epileptiform discharges: electroencephalographic, neuropsychological and functional MRI findings.

A case of fixation-off sensitivity (FOS) in an asymptomatic adult is presented and studied as a model for continuous epileptiform discharges. Video-electroencephalographic (EEG) revealed continuous bilateral occipital spike wave discharges during elimination of central vision, which were shown to be associated with transitory cognitive impairment demonstrated by neuropsychological testing. Functional MRI showed activation of parieto-occipital and frontal brain areas during the fixation-off discharges. This localization was confirmed with 64-channel EEG source analysis. The applied methods provided additional information on the pathophysiology of epileptiform discharges.

Adult↗

PubMed2000

Endotoxin priming and liver damage by experimental duodenal obstruction in the rat.

To verify whether endotoxin (LPS) might act as a priming cofactor of liver injury caused by obstructing the duodenum, four groups of male Wistar rats were studied. The first two groups comprised rats in which a closed duodenal loop (CDL) was created: CDL, n = 6 and CDL + LPS, n = 7; the next two groups comprised sham-operated animals: Sham n = 6 and Sham + LPS, n = 6. LPS, 400 microg/kg bodyweight, was administered i.p. to the rats belonging to groups CDL + LPS and Sham + LPS, 24 h before laparotomy. Twenty-four hours after laparotomy the animals were killed. Damage to bile ducts, extent and grading of coagulative and lytic spotty necrosis in liver tissue were evaluated morphologically. Coagulative necrosis was severe in four of seven rats of the group CDL + LPS, mild in six of six rats of group CDL, and absent in four of six and five of six rats of groups Sham and Sham + LPS (chi2 32.8, P = 0.0001). The animals of group CDL + LPS had more frequently diffuse lytic spotty necrosis than the animals in the three other groups (chi2 9.57 P<0.01). The results of our study indicate that, in rodents subjected to a closed duodenal loop, priming with LPS exacerbates liver injury due to cholate stasis.

Alanine Transaminase↗

PubMed2000

GABA receptor antagonists modulate postmitotic cell migration in slice cultures of embryonic rat cortex.

Recent studies indicate that GABA acts as a chemoattractant during rat cortical histogenesis. In vivo, GABA localizes in appropriate locations for a chemoattractant, along migratory routes and near target destinations for migrating cortical neurons. In vitro, GABA induces dissociated embryonic cortical neurons to migrate. Here, embryonic rat cortical slices were cultured in the presence or absence of GABA receptor (GABA-R) antagonists to assess GABA's effects on neuronal migration in situ. Gestational day 18 (E18) cortical slices were incubated overnight in bromodeoxyuridine (BrdU)-containing medium to label ventricular zone (vz) cells as they underwent terminal mitosis. The slices were then cultured in BrdU-free medium with or without GABA-R antagonists. In control slices, most BrdU(+) cells were observed in the cortical plate (cp) after 48 h. In contrast, cultures maintained in either saclofen (a GABA(B)-R antagonist) or picrotoxin (a GABA(A/C)-R antagonist) had few BrdU-labeled cp cells. However, the effects of the two antagonists were distinct. In the picrotoxin-treated slices, nearly half of all BrdU(+) cells remained in the vz and subventricular zone (svz), whereas saclofen treatment resulted in an accumulation of BrdU(+) cells in the intermediate zone (iz). Bicuculline, a GABA(A)-R antagonist, did not block, but rather enhanced migration of BrdU(+) cells into the cp. These results provide evidence that picrotoxin-sensitive receptors promote the migration of vz/svz cells into the iz, while saclofen-sensitive receptors signal cells to migrate into the cp. Thus, as cortical cells differentiate, changing receptor expression appears to modulate migratory responses to GABA.

Animals↗

PubMed2000

Design of an intensive epilepsy monitoring unit.

Video-electroencephalography (EEG) telemetry is a crucial component in the comprehensive evaluation of patients with epilepsy. The reasons for patients needing to be monitored fall broadly into three groups: presurgical assessment (36% of our patients), diagnostic assessment (52%), and sleep disorders (12%). Video EEG can be used to differentiate unusual epilepsies from pseudo seizures or other causes of paroxysmal neurological events. The design of a unit depends on the case mix of patients expected to be referred. The key elements to a successful unit are a reliable, flexible, easy-to-use recording system and a team of dedicated, experienced staff, both nursing and technical. The unit at the National Hospital is a six-bed ward with 7 nurses to provide 24-hour coverage, 5 technicians working in shifts, and physics support. A minimum of two staff are on duty at all times. It operates on a five-day week with a throughput of approximately 500 patients per year. It is vital that investigations are performed as efficiently and effectively as possible, and the patient's safety and wellbeing is paramount at all times. Drug reduction is likely to be used to precipitate seizures, especially in those being considered for epilepsy surgery, and this poses a risk of provoked secondary generalized seizures. Continuous supervision of patients, and the ability to respond rapidly to a seizure, are therefore essential. We adopt a standardized easy-to-follow drug-reduction protocol, similar to that used by other centers.

Anticonvulsants↗

PubMed2000

Focal xanthogranulomatous pyelonephritis with associated bone metaplasia.

Focal xanthogranulomatous pyelonephritis of the left lower pole was accidentally discovered in a 34-year-old woman at sonography. The patient had no history of stones and urinary tract infection and both conventional radiology and CT scan revealed radiated calcifications within a well-circumscribed mass. Surgical treatment consisted of enucleoresection of the lesion, and histopathology revealed a nucleus of bone metaplasia. To the best of our knowledge, metaplastic bone formation has never been documented before with xanthogranulomatous pyelonephritis.

Adult↗

PubMed2000

Iron deposition and progression of disease in chronic hepatitis C. Role of interface hepatitis, portal inflammation, and HFE missense mutations.

Histologically detectable iron (HDI) and HFE mutations were searched for in liver biopsy specimens from 58 Italian patients with chronic hepatitis C, and morphologic features were compared to examine their reciprocal relation and their contribution to disease progression. HDI was evident in 48% of cases with features of nonhemochromatosis iron overload. Total, sinusoidal, and portal HDI increased with stage; grade was related to all iron scores because of the contribution of portal inflammation and interface hepatitis. HFE mutations were seen in 47% of patients with chronic hepatitis C and in 28% of control subjects; they were related to stage and the His63Asp mutation to portal HDI. On multivariate analysis, grade but not stage or HFE mutations was associated with HDI in all sites. Interface hepatitis with its sequelae (sinusoidal capillarization and microshunting) represents a major factor in iron deposition in chronic hepatitis C and justifies the features of HDI. HFE mutations are not responsible for HDI deposition but could favor the progression of virus-induced damage independently from interference with iron metabolism.

Adolescent↗

PubMed2000

Hematology and serum chemistry of the island fox on Santa Cruz Island.

Serum and hematologic biochemistry values for island foxes (Urocyon littoralis) on Santa Cruz Island (California, USA) in April (wet season) and September (dry season) 1998 were evaluated. Serum chemistry of island foxes generally varied seasonally; 10 (40%) of the 25 serum characteristics were higher in the wet season, and three (12%) of the 25 serum characteristics were higher in the dry season. No hematologic parameters varied between seasons, although some measures varied between sexes. Blood analytes also varied with age; fox pups had higher values than adults for one hematologic and four serum parameters, whereas adult foxes had higher values for five hematologic characteristics. The information on blood chemistry provides baseline data useful in the monitoring of this threatened insular endemic carnivore.

Aging↗