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Biomedical subjects

J Linn

Publications and source records attributed to J Linn.

14 recordsLinked to original sources
PubMed2006

Effects of treatment with the atypical neuroleptic quetiapine on working memory function: a functional MRI follow-up investigation.

BACKGROUND: Working memory as a part of higher-order executive functions is defined by the parallel storage and processing of information. Recent functional fMRI studies have revealed a functional, interregional disintegration of a neuronal network connecting cortical, subcortical and cerebellar regions in schizophrenic patients (SZ). Cognitive impairment in working memory is a core psychopathological correlate of schizophrenic symptoms. Atypical neuroleptics such as quetiapine have shown good efficacy in treating positive and negative symptoms. The presented study evaluated the impact of a neuroleptic steady state treatment with quetiapine on the altered working memory activation patterns in schizophrenia. METHODS: Patients were examined by fMRI at baseline and after 12 weeks of steady state treatment with quetiapine. Matched healthy controls (HC) underwent baseline examination. In the scanner, stimuli were presented in a 2-back and 0-back condition of a working memory (wm) paradigm, whereby a degraded and a non-degraded version were used each time. Additionally, behavioural responses (reaction time to target stimuli and error ratio) were measured. RESULTS: At baseline, healthy controls revealed increased activity in the frontal lobe, especially in regions of the prefrontal cortex. Compared to HC, SZ showed hypoactivation in the right dorsolateral prefrontal cortex (DLPFC) and the ventrolateral prefrontal cortex (VLPFC) bilaterally for the 2-back condition. In the 2-back degraded condition there was a hypoactivation in both, the right DLPFC and the VLPFC. Additionally, patients showed bilaterally decreased activation in the basalganglia in the 2-back and in the right caudatus in the 2-back degraded condition compared to healthy controls. After treatment with quetiapine, patients activations patterns were increased. The pre-post comparison of the 2-back condition revealed a significant increase of activation in the left VLPFC at a significance level of 0.001 (uncorrected). The 2-back degraded condition led to a significant activation pattern in the lingual gyrus and the right precuneus. In both wm conditions, at baseline there were no differences in reaction time but only a worse performance in SZ. After treatment, behavioural measurement of responses, including reaction time and performance, showed slight improvements in SZ, although these did not reach statistical significance. CONCLUSIONS: The neuronal networks underlying working memory are clearly altered in schizophrenia. After 12 weeks of treatment with quetiapine monotherapy, patients showed significant clinical improvement and revealed increased BOLD activity in the VLPFC during a working memory task, although there was no improvement of cognitive performance.

Adult↗
PubMed2006

Eye closure in darkness animates olfactory and gustatory cortical areas.

In two previous fMRI studies, it was reported that eyes-open and eyes-closed conditions in darkness had differential effects on brain activity, and typical patterns of cortical activity were identified. Without external stimulation, ocular motor and attentional systems were activated when the eyes were open. On the contrary, the visual, somatosensory, vestibular, and auditory systems were activated when the eyes were closed. In this study, we investigated whether cortical areas related to the olfactory and gustatory system are also animated by eye closure without any other external stimulation. In a first fMRI experiment (n = 22), we identified cortical areas including the piriform cortex activated by olfactory stimulation. In a second experiment (n = 12) subjects lying in darkness in the MRI scanner alternately opened and closed their eyes. In accordance to previous studies, we found activation clusters bilaterally in visual, somatosensory, vestibular and auditory cortical areas for the contrast eyes-closed vs. eyes-open. In addition, we were able to show that cortical areas related to the olfactory and gustatory system were also animated by eye closure. These results support the hypothesis that there are two different states of mental activity: with the eyes closed, an "interoceptive" state characterized by imagination and multisensory activity and with the eyes open, an "exteroceptive" state characterized by attention and ocular motor activity. Our study also suggests that the chosen baseline condition may have a considerable impact on activation patterns and on the interpretation of brain activation studies. This needs to be considered for studies of the olfactory and gustatory system.

Attention↗
PubMed2006

[Complexities of "reversible posterior leukoencephalopathy syndrome"].

We report a case of reversible posterior leukoencephalopathy syndrome in a 50-year-old patient with severe untreated hypertension. Recent advances in magnetic resonance imaging (especially diffusion-weighted imaging) allow new pathopysiological insight: it was found that the resulting vasogenic edema was restricted neither to the posterior vascular territories nor to white matter. The apparent diffusion coefficient helps to differentiate between reversible vasogenic edema and cytotoxic edema, the latter indicating irreversible neuronal death.

Antihypertensive Agents↗
PubMed2006

Does opening the peritoneum at the time of renal transplanation prevent lymphocele formation?

BACKGROUND: The occurrence of lymphocele formation following renal transplantation is variable, and the optimal approach to treatment remains undefined. Opening the peritoneum at the time of transplantation is one method of decreasing the incidence of lymphocele formation. The purpose of this study was to determine whether creating a peritoneal window at the time of transplantation decreases the incidence of lymphocele formation. METHODS: We performed a retrospective review of renal transplants conducted at our institution between 2002 and 2004. Records were reviewed to obtain details regarding opening of the peritoneum at the time of transplant and occurrence of lymphocele. Every patient underwent routine ultrasound imaging in the peri-operative period. Graft dysfunction secondary to the lymphocele was the primary indication for intervention. Data were analyzed by chi-square. RESULTS: During the initial transplant the peritoneum was opened in 35% of patients. The overall incidence of fluid collections, identified by ultrasound, was 24%. Opening the peritoneum did not decrease the incidence of lymphocele. However, more patients with a closed peritoneum required an intervention for a symptomatic lymphocele. In the 11 patients with an open peritoneum and a fluid collection, only one required an intervention. In patients whose peritoneum was left intact, 24% of fluid collections required intervention. Graft survival was equivalent. CONCLUSION: Creating a peritoneal window at the time of transplantation did not decrease the overall incidence of postoperative fluid collections. However, forming a peritoneal window at the time of transplantation did decrease the incidence of symptomatic lymphocele.

Humans↗
PubMed2000

Large-scale oscillatory calcium waves in the immature cortex.

Two-photon imaging of large neuronal networks in cortical slices of newborn rats revealed synchronized oscillations in intracellular Ca2+ concentration. These spontaneous Ca2+ waves usually started in the posterior cortex and propagated slowly (2.1 mm per second) toward its anterior end. Ca2+ waves were associated with field-potential changes and required activation of AMPA and NMDA receptors. Although GABAA receptors were not involved in wave initiation, the developmental transition of GABAergic transmission from depolarizing to hyperpolarizing (around postnatal day 7) stopped the oscillatory activity. Thus we identified a type of large-scale Ca2+ wave that may regulate long-distance wiring in the immature cortex.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed1999

A managed care organization's attempt to increase influenza and pneumococcal immunizations for older adults in an acute care setting.

OBJECTIVE: Among the high risk groups for complications from influenza and pneumococcal disease, individuals aged 65 and older hospitalized within the previous year represent the group at highest risk. Studies have demonstrated that targeting hospitalized patients aged 65 and older for immunization before hospital discharge can be successful. This study addressed the efficacy of such a program within a managed care organization to immunize this highest risk group. DESIGN: A cross-sectional study. SETTING: Oxford Health Plans, a major managed care organization in New York serving a large Medicare population. PARTICIPANTS: A total of 106 Primary Care Physicians caring for 153 patients aged 65 and older, who were hospitalized in one of 10 high volume hospitals during October and November of 1996. Nine of these facilities were located in New York and one was in New Jersey. INTERVENTION: Patients aged 65 and older admitted to any of the 10 hospitals were identified daily. A fax was sent to each patient's primary care physician explaining the program and requesting that he/she administer influenza and/or pneumococcal vaccine to his/her patient before hospital discharge. Literature references citing past successful programs were included in the fax. MEASUREMENTS: Measurements included medical record documentation of influenza and pneumococcal immunization, both ordered and given, for the individual member before discharge; patient age; sex; and primary and secondary diagnoses. Physicians were sent follow-up questionnaires to determine reasons for not vaccinating. RESULTS: A total of 206 patients were admitted during the eligible time period. One hundred fifty-three hospitalized patients (average age = 74 years) participated. The median length of stay among this study population was 5 days (range, 1-63 days). The distribution of the median length of stay for the 25th and 75th percentiles was 3 and 9 days. The rate for influenza and pneumococcal immunization, both ordered and given, before hospital discharge was 1.96% for the influenza vaccine (n = 3) and .65% for the pneumococcal vaccine (n = 1), respectively. Results of a follow-up survey mailed to all physicians (n = 106) with eligible members in the study indicated that the most frequent reasons for not vaccinating included: patients were vaccinated before admission, patients were not stable enough to be vaccinated before discharge, and the acute care setting is not appropriate for vaccination. Response rate of 58% (n = 61) was achieved with an initial mailing and one follow-up telephone call to all previous nonresponders. Some physician survey responses do not correlate with data obtained from retrospective patients' claims analysis. CONCLUSION: Well-coordinated and timely attempts to encourage primary care physicians to immunize patients 65 years and older before hospital discharge were unsuccessful in our study. Rather than working with physicians, it may be that managed care organizations should work directly with hospitals to implement influenza and pneumococcal immunization programs.

Aged↗
PubMed1995

Characterization of feline Helicobacter pylori strains and associated gastritis in a colony of domestic cats.

Twenty-four young adult domestic cats from a commercial vendor were found to be infected with Helicobacter pylori. Histopathologic analyses, selected electron microscopy, and urease mapping were performed on mucosal samples collected from the cardias and fundi, bodies, and antra of these cats' stomachs. H. pylori organisms were abundant in all areas of the stomach on the basis of histologic evaluation and urease mapping. H. pylori infection was associated with a moderate to severe lymphofollicular gastritis in 21 of 24 cats (88%). The gastritis was most pronounced in the antral region and consisted mainly of multifocal lymphoplasmacytic follicular infiltrates in the deep mucosa. The severity of gastritis in the antrum corresponded to high numbers of H. pylori there on the basis of the use of the urease assay as an indicator of H. pylori colonization. Ten of 24 cats (42%) also had small to moderate numbers of eosinophils in the gastric mucosa. All 24 cats had gastric lymphoid follicles, with follicles being most prevalent in the antrum. Electron microscopy of gastric tissue revealed numerous H. pylori organisms, some of which were closely adhered to the mucosal epithelium. Human H. pylori gene-specific primers to ureA and ureB amplified products of similar sizes from H. pylori cat isolates. Digestion of the products with restriction enzymes resulted in fragments characteristic of the restriction fragment length polymorphism patterns of H. pylori isolates from humans. In the domestic cat, H. pylori infection is associated with a lymphofollicular gastritis, consisting of lymphocytic and plasmacytic infiltration into the lamina propria, and the organism appears to provide chronic antigenic stimulation resulting in the formation of gastric lymphoid follicles.

Animals↗
PubMed1994

Effect of restorative procedures on the strength of endodontically treated molars.

Endodontically treated molar teeth are considered susceptible to fracture because of loss of tooth bulk. This study evaluated the significance of retaining intact marginal ridges and selective cusp coverage in preserving tooth stiffness during restoration. Strain gauges were bonded to four cusps of 36 intact extracted human lower molars. Teeth were loaded mesially and distally in a closed-loop servohydraulic system to measure stiffness. Endodontic access was followed by mesio-occlusal or mesio-occluso-distal preparation. Teeth were restored with either amalgam (no overlay), amalgam overlay, or gold overlay with partial or complete cusp coverage. Relative stiffness was calculated for all test conditions. Preserving a marginal ridge in molars did not fully conserve the strength of adjacent cusps; selective cusp coverage reinforced only the capped cusps; full occlusal coverage with gold or amalgam strengthened all cusps, but gold did so more consistently. It is more important to cover cusps than to preserve tooth structure (including a marginal ridge) in endodontically treated molar teeth.

Analysis of Variance↗
PubMed1987

Radiographic and visual assessment of alveolar pathology of first molars in dry skulls.

There are many reports in the literature relating to the dental pathology of ancient peoples. In most instances only visual observations of alveolar lesions have been made, precluding assessment of covert dental lesions. The present paper was undertaken to compare the incidence of alveolar dental lesions determined by both visual and radiographic methods in a group of Australian aboriginal skulls. First molars of the right side were used for the comparison: approximately ten percent more lesions were found by the radiographic method. The data demonstrated the limitation of either technique alone. The strong association between pulp exposure and furcal, angular, and apical lesions suggests that pulpal lesions provoke periodontal changes that have traditionally been assigned to a gingival etiology. The location of the lesions within the periodontium would appear to be determined by the location of the pulpal pathology and the pathways through dentin between that location and the periodontal ligament.

Alveolar Process↗
PubMed1981

Influence of ration composition and energy balance on blood beta-hydroxybutyrate (ketone) and plasma glucose concentrations of dairy cows in early lactation.

The effect of ration composition, with respect to concentrate, crude protein, and methionine hydroxyanalog content, on blood beta-hydroxybutyrate and plasma glucose concentrations was assessed in Holstein cows every 2 weeks over the first 6 weeks of lactation. The correlation of these metabolites with estimated energy balance, and the effects of these ration variables on this correlation were studied. High concentrate diets (60% of dry matter) compared with low concentrate diets (40% of dry matter) increased mean plasma glucose values and reduced mean blood beta-hydroxybutyrate concentration. Variation in crude protein and methionine hydroxyanalog supplementation did not affect metabolite concentration. The correlations between blood beta-hydroxybutyrate and energy balance and between plasma glucose and energy balance were weak and subject to the influence of variation in ration composition. It was concluded that plasma glucose and blood beta-hydroxybutyrate concentrations cannot be used as valid indicators of energy balance. However, it did appear that blood beta-hydroxybutyrate might be used as an indicator of the relative glucogenic potential of dairy rations and that blood concentrations of this metabolite could potentially be used to adjust factors in the ration which influence glucose availability to the cow.

3-Hydroxybutyric Acid↗
PubMed1976

Use of alkaline sucrose gradients in a zonal rotor to detect integrated and unintegrated avian sarcoma virus-specific DNA in cells.

We have attempted to distinguish integrated and unintegrated forms of avian sarcoma virus-specific DNA in cells by sedimentaton through an alkaline sucrose gradient in a slowly reorienting zonal rotor. Results obtained with this procedure are similar to those obtained by the more convenient analysis of networks of high-molecular-weight cell DNA. Most, if not all, viral DNA appears completely integrated into the host cell genome in an avian sarcoma virus-transformed mammalian cell and in normal chicken cells (in which viral DNA is genetically transmitted). Fully transformed duck cells and duck embryo fibroblasts infected for 20 to 72 h contain both integrated and unintegrated viral DNA; up to one copy per cell is integrated within 20 h after infection, and four to eight copies are integrated in fully transformed cells. The amount of unintegrated DNA varies but may comprise over 75% of the viral DNA in acutely infected cells and from 20 to 70% of the viral DNA in fully transformed cells. The unintegrated DNA in either case consists principally of duplexes with "minus" strands the length of a subunit of the viral genome (2.5 X 10(6) to 3 X 10(6) daltons) and relatively short "plus" strands (0.5 X 10(6) to 1.0 X 10(6) daltons).

Animals↗
PubMedDate not supplied

Metastatic melanoma to regional lymph nodes.

There is an epidemic of melanoma in the United States and throughout most parts of the word. Recent advancements in the management of this disease has provided the patient with more options. The emerging technology of lymphatic mapping and sentinel node biopsy results in a more conservative, less morbid procedure to obtain nodal staging information. At the same time, providing the pathologist the 1-2 nodes from the basin most likely to contain metastatic disease, allows for a more detailed examination of the sentinel lymph node. This more detailed examination may include serial sectioning, immunohistochemical staining or even molecular biology techniques based on RT-PCR to provide more accurate staging. National trials are ongoing to examine the clinical relevance of the disease that is detected and the 'upstaging' that occurs with more sensitive assays for occult metastases.

Clinical Trials as Topic↗