Search PubMed⌕ Search

Biomedical subjects

M Keller

Publications and source records attributed to M Keller.

At least 55 records · Page 3Linked to original sources
PubMed2001

Effect of concurrent anxiety on response to sertraline and imipramine in patients with chronic depression.

Anxiety commonly complicates the clinical presentation of depression and has been associated with poorer long-term outcome, but little information is available on the clinical correlates, and comparative effect on treatment response, of subsyndromic or secondary anxiety. Patients diagnosed with chronic major or double depression were randomized to 12 weeks of double-blind treatment with either sertraline or imipramine in a 2:1 ratio. A high anxiety subgroup was operationally defined by a HAM-D anxiety/somatization factor score > or = 7. The effect of study treatment was measured utilizing the HAM-D, CGI, HAM-D anxiety/somatization factor, as well as a quality of life measure (Q-LES-Q) and a measure of psychosocial functioning (the MOS-SF-36). Two hundred nine patients were treated with imipramine and 426 patients were treated with sertraline. Thirty-six percent of the total met criteria for the high anxiety subgroup. According to Kaplan-Meier probability estimates, patients with significant concurrent anxiety symptoms were more likely to respond by 12 weeks (66.4%) than those without significant anxiety symptoms (54.2%). There was no significant difference in response rates for sertraline vs. imipramine. Both drugs were effective at treating high baseline levels of anxiety, with 60% of sertraline patients and 58% of imipramine patients having 50% or greater reduction from baseline in HAM-D anxiety/somatization factor scores, and only 4.6% and 9.9%, respectively, reporting treatment-emergent worsening in anxiety at study endpoint. Despite the chronicity of depressive illness, acute treatment with both sertraline and imipramine significantly improved psychosocial and quality of life measures. High baseline levels of anxiety did not reduce overall antidepressant response but did somewhat delay the onset of response to sertraline or imipramine in patients with chronic depression.

Adrenergic Uptake Inhibitors↗
PubMed2001

Heterologous expression of acetylcholinesterase affects proliferation and glial cytoskeleton of adherent chicken retinal cells.

Besides its function at cholinergic synapses, acetylcholinesterase (AChE) exerts structural functions on neural differentiation, independent of its enzymatic activity. To elucidate such functions, we have previously heterologously expressed AChE in histotypic retinal reaggregates, revealing strong effects on their histogenesis, particularly on Müller glia processes. To further resolve these findings at a less complex cellular level, in this study we transfected adherent retinal cells of the chick embryo after 2 days i.c. with a sense pSVK3-AChErab-cDNA expression vector encoding for the entire rabbit AChE gene by calcium phosphate precipitation. Northern blots using digoxigenin (DIG)-labeled rabbit cDNA revealed a pronounced level of rabbit AChE mRNA in AChE-transfected cells. Western blot analysis established an increase in the endogenous AChE protein in transfected cells. Noticeably, AChE activity was not much affected, indicating a post-translational regulation of overall AChE activity. As a corollary, 5'-bromo-2'-deoxyuridine (BrdU) studies showed a decrease in cell proliferation. Exploring changes of the Müller glia, the cytoskeletal protein vimentin was found to be increased in transfected cells. Vimentin-stained processes are longer, thicker and more orderly arranged. In conclusion, exogenous expression of rabbit AChE in chicken retinal monolayers exerts a structural function on glial cytoskeletal organization, independent of AChE activity.

Acetylcholinesterase↗
PubMed2001

Lithium and suicidal behavior in major affective disorder: a case-control study.

OBJECTIVE: A number of studies have suggested that lithium may be particularly effective in reducing suicide risks among patients with major affective disorders. The design of many of these studies left them open to biases associated with treatment compliance, however. METHOD: Subjects were drawn from a naturalistic, long-term follow-up of patients with major affective disorders. Fifteen who committed suicide while receiving somatotherapy where matched to non-suicidal patients who were similarly receiving somatotherapy at the same point in follow-up. The same procedure was followed for 41 patients who made a serious suicide attempt during follow-up. RESULTS: Six (40.0%) of the patients who committed suicide, and eight (53.3%) of their controls, were thought to have been taking lithium in the preceding week. Among attempters and their controls, nine (22.0%) and eight (19.5%), respectively, were taking lithium. CONCLUSION: These results do not support previous suggestions that lithium has uniquely antisuicidal properties. Other existing datasets should be explored with this design to establish whether lithium does, or does not, offer special protection against suicide.

Adult↗
PubMed2001

The nuclear pore complex is involved in nuclear transfer of plasmid DNA condensed with an oligolysine-RGD peptide containing nuclear localisation properties.

One of the major barriers to efficient gene transfer and expression of nonviral vectors for gene therapy is passage across the nuclear envelope. We have previously shown that an oligolysine-RGD peptide that condenses plasmid DNA and binds to cell surface integrins can mediate increased internalisation of plasmid DNA into cells and synergistic enhancement of gene expression when complexed to a cationic lipid. In this report, we show that this enhancement is due to increased nuclear transfer of the plasmid DNA. We have applied the digitonin-permeabilised cell system that has been well established for the study of the nuclear transport of proteins to examine the nuclear transfer of plasmid DNA. Nuclear transfer of plasmid DNA complexed to an oligolysine-RGD peptide and lipofectamine appears to be an energy-dependent process involving the nuclear pore complex, since it is inhibited at 4 degrees C and by treatment with wheat germ agglutinin or with an antibody to the nuclear pore complex which all block nuclear protein import. In accordance with active nuclear transport, we have shown that all these treatments inhibit expression of a luciferase reporter plasmid in permeabilised cells. Nuclear transfer of pDNA is enhanced in mitotic cells, but cell division is not a prerequisite for transfer. We propose that the oligolysine-RGD peptide acts as a nuclear localisation signal and that the cationic lipid is more important for cell entry and endosome destabilisation than nuclear transfer.

Active Transport, Cell Nucleus↗
PubMed2001

3D light scanning macrography.

The technique of 3D light scanning macrography permits the non-invasive surface scanning of small specimens at magnifications up to 200x. Obviating both the problem of limited depth of field inherent to conventional close-up macrophotography and the metallic coating required by scanning electron microscopy, 3D light scanning macrography provides three-dimensional digital images of intact specimens without the loss of colour, texture and transparency information. This newly developed technique offers a versatile, portable and cost-efficient method for the non-invasive digital and photographic documentation of small objects. Computer controlled device operation and digital image acquisition facilitate fast and accurate quantitative morphometric investigations, and the technique offers a broad field of research and educational applications in biological, medical and materials sciences.

Animals↗
PubMed2001

Interaction between the open reading frame III product and the coat protein is required for transmission of cauliflower mosaic virus by aphids.

Transmission of cauliflower mosaic virus (CaMV) by aphids requires two viral nonstructural proteins, the open reading frame (ORF) II and ORF III products (P2 and P3). An interaction between a C-terminal domain of P2 and an N-terminal domain of P3 is essential for transmission. Purified particles of CaMV are efficiently transmitted only if aphids, previously fed a P2-containing solution, are allowed to acquire a preincubated mixture of P3 and virions in a second feed, thus suggesting a direct interaction between P3 and coat protein. Herein we demonstrate that P3 directly interacts with purified viral particles and unassembled coat protein without the need for any other factor and that P3 mediates the association of P2 with purified virus particles. The interaction domain of P3 is located in its C-terminal half, downstream of the P3-P2 interaction domain but overlapping a region which binds nucleic acids. Mutagenesis of P3 which interferes with the interaction between P3 and virions is correlated with the loss of transmission by aphids. Taken together, our results demonstrate that P3 plays a crucial role in the formation of the CaMV transmissible complex by serving as a bridge between P2 and virus particles.

Animals↗
PubMed2001

The relationship between comorbid personality disorders and treatment received in patients with anxiety disorders.

Few studies have addressed the relationship between the presence of a comorbid personality disorder and the amount of psychiatric treatment received by patients with an Axis I disorder. This issue has not been studied in patients with anxiety disorders. In a prospective, naturalistic, longitudinal study of anxiety disorders, 526 subjects were assessed with the Personality Disorder Examination, and types of treatment received in 1991 and 1996 were identified. In 1991, compared to subjects without a personality disorder, subjects with a personality disorder were as likely to receive medication and they received a greater number of medications. Subjects with borderline personality disorder were more likely to receive heterocyclic antidepressants and interventions characteristic of psychodynamic psychotherapy and cognitive therapy; they also reported receiving a greater number of medications and types of psychosocial treatment than other subjects. In 1996, subjects with borderline personality disorder were more likely to receive psychodynamic interventions. These findings suggest that in patients with an anxiety disorder, the presence of a comorbid personality disorder is associated with receiving a greater number of medications but not with a greater likelihood of receiving pharmacologic or psychosocial treatment. However, the presence of borderline personality disorder is associated with a greater likelihood of receiving, and receiving a greater number of, certain types of somatic and psychosocial treatments.

Adult↗
PubMed2001

Neuroimaging of cerebellar liponeurocytoma. Case report.

Cerebellar liponeurocytoma is a newly recognized, rare clinicopathological entity. It manifests with posterior fossa symptoms in adults and is characterized histopathologically by advanced neuronal and focal lipomatous differentiation with a low level of mitotic activity. The authors analyzed the computerized tomography (CT) and magnetic resonance (MR) imaging findings in two patients with histopathologically proven cerebellar liponeurocytomas and review the literature. Cerebellar liponeurocytoma may be suspected on the basis of neuroimaging findings that demonstrate an intraaxial neoplasm with the propensity for exophytic growth into the adjacent subarachnoid spaces. On CT scans, the tumor commonly presents as a hypointense mass with intermingled areas exhibiting the attenuation values of fatty tissue. On T1-weighted MR images, the tumor is hypointense with scattered foci of hyperintense signal and displays moderate contrast enhancement. On T1-weighted MR images, the tumor is slightly hyperintense to cortex, and edema is usually absent. Areas of fat density as assessed on CT scans and of T1 hyperintensity seen on MR images help to distinguish this rare neoplasm from the more common adult medulloblastomas or ependymomas. The available follow-up data indicate a favorable clinical prognosis; therefore, knowledge and precise characterization of this tumor is important to avoid unnecessary adjuvant radio- or chemotherapy.

Adult↗
PubMed2000

Pseudoprolines (psiPro) in drug design: direct insertion of psiPro systems into cyclosporin C.

The insertion of acetals that exhibit variable structural features into complex peptides such as cyclosporin C (CsC) results in oxazolidine derivatives (pseudoprolines, psiPro) of tailored physico-chemical and biological properties. N,O-Acetalation of the 2-threonine hydroxyl group and the preceding amide nitrogen of CsC is achieved by treating the molecule with a number of both arylated and non-arylated dimethyl acetals. The psiPro-containing CsC derivatives exhibit enhanced conformational backbone rigidity, as suggested by analytical HPLC, NMR spectroscopy and by kinetic measurements on binding with their receptor protein cyclophilin A (CypA) that were not time-dependent. IC50 values for calf-thymus CypA were obtained by kinetic evaluation of its cis-->trans isomerase activity. The choice of the para-substituted aryl dimethyl acetals allows the inhibitory properties of the corresponding derivatives to be modulated to either prodrugs or moderately strongly binding cyclosporin C derivatives.

Animals↗
PubMed2000

Keratinopathogenic mould fungi and dermatophytes in healthy and diseased hooves of horses.

Specimens of hoof horn from 187 horses were examined for a possible relationship between clinically affected hooves and the occurrence of pathogenic fungi. Specimens were taken from the coronary band and from the stratum externum and medium of the coronary horn and transferred on to Sabouraud dextrose agar, with and without cycloheximide, and incubated at 28 degrees C. Dermatophytes and mould fungi were identified by their macroscopic and microscopic characteristics. The 732 isolates could be assigned to 26 species of moulds, two different species of the dermatophyte Microsporum and three different species of the dermatophyte Trichophyton. Depending on their pathogenic potential they were assigned to three groups: (i) fungi known to be keratinopathogenic (Acremonium blochii, Alternaria alternata, Alternaria chlamydospora, Geotrichum candidum, Microsporum ferrugineum, Microsporum gypseum, Scopulariopsis brevicaulis, Trichophyton species, Trichophyton mentagrophytes, Trichophyton schönleinii, 57 isolates), (ii) a group of uncertain pathogenicity (223 isolates), and (iii) a group of non-pathogenic species (452 isolates). Eighty per cent of the samples from horses with hoof horn lesions and 66.7 per cent of the samples from horses with slightly affected hoof horn contained fungi of the keratinopathogenic group, whereas only 8.9 per cent of the samples from horses with healthy hoof horn contained fungi of this group. There were no significant correlations between the clinical data and the age, sex or breed of the horses or their bedding and hygiene. Twelve species of fungi were isolated from the air in the horses' stables, but none of them belonged to the keratinopathogenic group.

Animals↗
PubMed2000

The small G-protein Rac mediates depolarization-induced superoxide formation in human endothelial cells.

Superoxide anions impair nitric oxide-mediated responses and are involved in the development of hypertensive vascular hypertrophy. The regulation of their production in the vascular system is, however, poorly understood. We investigated whether changes in membrane potential that occur in hypertensive vessels modulate endothelial superoxide production. In cultured human umbilical vein endothelial cells, changes in membrane potential were induced by high potassium buffer, the non-selective potassium channel blocker tetrabutylammonium chloride (1 mm), and the non-selective cation ionophore gramicidin (1 micrometer). Superoxide formation was significantly elevated to a similar degree by all three treatments (by approximately 60%, n = 23, p < 0.01), whereas hyperpolarization by the K(ATP) channel activator Hoe234 (1 micrometer) significantly decreased superoxide formation. Depolarization also induced an increased tyrosine phosphorylation of several not yet identified proteins (90-110 kDa) and resulted in a significant increase in membrane association of the small G-protein Rac. Accordingly, the Rac inhibitor Clostridium difficile toxin B blocked the effects of depolarization on superoxide formation. The tyrosine kinase inhibitor genistein (30 micrometer, n = 15) abolished depolarization-induced superoxide formation and also prevented depolarization-induced Rac translocation associated with it. It is concluded that depolarization is an important stimulus of endothelial superoxide production, which involves a tyrosine phosphorylation-dependent translocation of the small G-protein Rac.

Endothelium, Vascular↗
PubMed2000

The cauliflower mosaic virus translational transactivator interacts with the 60S ribosomal subunit protein L18 of Arabidopsis thaliana.

The cauliflower mosaic virus (CaMV) open reading frame VI product (P6) is involved in several aspects of the infectious cycle. P6 specifically controls the synthesis of other CaMV proteins by transactivating their expression from the polycistronic 35S RNA. By far-Western assays, we have demonstrated that P6 interacts with proteins from both healthy and CaMV-infected leaves of Arabidopsis thaliana. These proteins are found in ribosome-enriched extracts, suggesting that they participate in the translation process. One of these proteins, identified by microsequencing, corresponds to the 60S ribosomal subunit protein L18 (RPL18). Its cDNA was cloned and expressed in Escherichia coli, and the resulting RPL18 protein was shown to interact with the minimal region required for translational transactivation, designated the miniTAV domain of P6.

Amino Acid Sequence↗
PubMed2000

[Fracture management in the aged].

Fracture care in a geriatric population should lead to a mobilisation with full weight bearing as soon as possible after the accident. Osteoporosis and associated preexisting disease influences the kind of fracture care as well as the social situation. A retrospective analysis of 888 consecutive patients from 1994 to 1998 showed that the fracture risk for a second independent bony lesion was 5.2% in this population with a mean age of 83.4 years (75 y-97.2 y). 946 fractures were treated operatively with a overall reoperation rate of 10%. 3.1% were soft tissue revisions due to infection, 2.0% were because of implant failure in connection with a deep infection and 5.2% of the reoperation were indicated because of implant failure alone. Distribution of complications showed the advantage of closed, indirect reduction and intramedullary devices and primary hemiarthroplasty in femoral and humeral head fractures.

Aged↗