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Biomedical subjects

C Mann

Publications and source records attributed to C Mann.

At least 73 records · Page 4Linked to original sources
PubMed1996

G2 cyclins are required for the degradation of G1 cyclins in yeast.

Progression of the eukaryotic cell cycle is controlled by cyclin-dependent kinases (CDKs). Cdc28, the budding yeast homologue of Cdc2 (Cdk1), is required for both the G1/S and G2/M transitions of the cell cycle. The functional specificity of the Cdc28 kinase is determined by its association with G1 or G2 cyclins. Alternation of cell cycle phases is thus mainly due to mechanisms that ensure that one cyclin family succeeds another. Here we show that the G2 cyclins Clb1, Clb2, Clb3 and Clb4 are required for the proteolysis of the G1 cyclins Cln1 and Cln2, providing a mechanism for coupling synthesis of G2 cyclins with the disappearance of G1 cyclins. Our data indicate that this pathway involves the Ubc9 ubiquitin-conjugating enzyme. The Cdc34 ubiquitin-conjugating activity may function redundantly with Ubc9, or it may only be involved in Cln1,2 turnover through its role in promoting the degradation of Sic1, a specific inhibitor of Cdc28-Clb complexes.

Anaphase-Promoting Complex-Cyclosome↗
PubMed1996

Civ1 (CAK in vivo), a novel Cdk-activating kinase.

Cyclin-dependent protein kinases (Cdks) play key roles in regulating cell division and gene expression. Most Cdks require binding of a cyclin and phosphorylation by a Cdk-activating kinase (CAK) to be active. We report the identification of Civ1 (CAK in vivo), a novel CAK activity in S. cerevisiae. Civ1 is most similar in sequence to the Cdks, but unlike them is active as a monomer and may thus be the founding member of a novel family of kinases. Civ1 binds tightly to and phosphorylates Cdc28, thereby allowing its subsequent activation by the binding of a cyclin. The CIV1 gene is essential for yeast cell viability, and Cdc28 phosphorylation and activity are conditionally inhibited in a civ1-4 temperature-sensitive mutant. Civ1 is the only CAK for which there are genetic data indicating that its activity is physiologically relevant in vivo.

Amino Acid Sequence↗
PubMed1996

The SLT2(MPK1) MAP kinase is activated during periods of polarized cell growth in yeast.

The SLT2(MPK1) mitogen-activated protein kinase signal transduction pa thway has been implicated in several biological processes in Saccharomyces cerevisiae, including the regulation of cytoskeletal and cell wall structure, polarized cell growth, and response to nutrient availability, hypo-osmotic shock and heat shock. We examined the conditions under which the SLT2 pathway is activated. We found that the SLT2 kinase is tyrosine phosphorylated and activated during periods in which yeast cells are undergoing polarized cell growth, namely during bud formation of vegetative cell division and during projection formation upon treatment with mating pheromone. BCK1(SLK1), a MEK kinase, is required for SLT2 activation in both of these situations. Upstream of BCK1(SLK1), we found that the STE20 kinase was required for SLT2 activation by mating pheromone, but was unnecessary for its activation during the vegetative cell cycle. Finally, SLT2 activation during vegetative growth was partially dependent on CDC28 in that the stimulation of SLT2 tyrosine phosphorylation was significantly reduced directly after a temperature shift in cdc28 ts mutants. Our data are consistent with a role for SLT2 in promoting polarized cell growth.

Amino Acid Sequence↗
PubMed1996

Tolerance of laparoscopy for resection of phaeochromocytoma.

We describe two patients who underwent resection of phaeochromocytoma by a laparoscopic approach. Although outcome from surgery was successful, there was marked variability in hormonal and haemodynamic changes. In one patient, despite an infusion of nicardipine, peritoneal insufflation produced a marked increase in catecholamine concentrations associated with transient but intense vasoconstriction, but there was no change in the second patient. In both patients, exsufflation caused no significant haemodynamic changes in spite of the high doses of nicardipine given throughout the procedures.

Adrenal Gland Neoplasms↗
PubMed1996

Psychological defense mechanisms and electroencephalographic arousal.

The aim of this study was to examine the relationship between psychological defense as measured by the Kragh tachistoscopic Defense Mechanisms Test (DMT), and general arousal properties of the individual as measured with electroencephalogram (EEG). The DMT assesses defense by presenting neutral and threatening pictures with very short exposure times. EEG characteristics were measured in the 8-12 Hz EEG frequency band during DMT testing. Twenty-one male subjects participated in the study. All were US Air Force personnel on active duty. Personnel with high defense mechanisms, defined in this connection as slow perception of the threat, tended to have higher cortical arousal after Stimulus exposure than the subjects with low defense mechanisms. The differences occurred mainly with new stimulus material without any threatening content. The differences in arousal response to novel stimuli may contribute to an understanding of the relationships between the Kragh DMT test and performance in life-threatening situations.

Adult↗
PubMed1996

Management of subglottic foreign bodies.

Foreign body aspiration is not an infrequent encounter in the practice of otolaryngology and requires immediate attention. The vast majority of foreign body aspirations occur in children less than 3 years of age, and the actual event of aspiration is frequently not witnessed. Although inhaled foreign bodies most often lodge in the bronchi, laryngotracheal foreign bodies also occur and are potentially more dangerous. Specifically, subglottic foreign bodies present unique clinical challenges. The diagnosis of subglottic foreign bodies is often difficult and they are commonly confused with other causes of upper airway obstruction. We present our experience with the diagnosis and management of seven patients with subglottic foreign bodies, who presented with an abnormal airway and whose problems were initially misdiagnosed. The radiographic and clinical features are discussed with a review of our surgical management.

Child↗
PubMed1996

Ear clicks in palatal tremor caused by activity of the levator veli palatini.

We describe a patient who developed palatal tremor and presented with ear clicks that appeared to originate from activity of the levator veli palatini and not the tensor veli palatini. This was treated with botulinum toxin. We discuss the motor innervation of the palate in the context of our case, our findings in terms of classification, and how the lower cranial nerve nuclei are involved in the etiology of palatal tremor.

Adolescent↗
PubMed1995

G1 cyclin turnover and nutrient uptake are controlled by a common pathway in yeast.

Entry into a new cell cycle is triggered by environmental signals at a point called Start in G1 phase. A key regulator of this transition step in yeast is the CDC28 kinase together with its short-lived regulatory subunits called G1-cyclins or CLN proteins. To identify genes involved in G1-cyclin degradation, we employed a genetic screen by selecting for stable CLN1-beta-galactosidase fusion proteins. Surprisingly, one group of mutants was found to be allelic to GRR1, a gene previously described to be involved in glucose uptake, glucose repression, and divalent cation transport. In grr1 mutants, both CLN1 and CLN2 cyclins are significantly stabilized. A suppressor analysis indicated that G1-cyclin stabilization in grr1 was not a consequence of the nutrient uptake defect. This suggests that the GRR1 gene product is part of a common regulatory pathway linking two functions important for cell growth, nutrient uptake, and G1 cyclin-controlled cell division.

Biological Transport↗
PubMed1995

Three-dimensional visualisation of the large bowel: a potential tool for assessing targeted drug delivery and colonic pathology.

A study has been undertaken to assess the feasibility of three-dimensional imaging of the dispersion of a non-absorbable tracer released into the colon of normal subjects. Six healthy volunteers were selected who were participating in a scintigraphic study designed to assess the spreading of 1 MBq indium-111 Amberlite resin delivered from a delayed capsule system targeted to release in the ascending colon. In each case subjects were imaged using a rotating gamma camera over a data collection period of approximately 20 min. Three-dimensional volume rendered images demonstrated good visualisation of the dispersion of the tracer throughout the ascending, transverse and descending colon and provided good anatomical visualisation of the shape of the colon, not previously apparent from the planar views. The present study demonstrates for the first time, the successful three-dimensional imaging of a radiolabelled tracer dispersed throughout the colon and opens up the prospects for more detailed study of quantification of the volume and distribution of tracers contained within the colon.

Adult↗
PubMed1995

Somatic care wanted by HIV-infected intravenous drug abusers: the patients' opinions and experiences.

The somatic care of HIV-infected intravenous drug abusers (IVDUs) is often combined with many problems. The addict is often an unpopular patient, but society must assume responsibility for him or her and it is important to solve care problems in an appropriate way. This study was undertaken in order to investigate what kind of care addicts want when they become somatically ill. A questionnaire was given to patients who acquired HIV infection due to intravenous drug abuse, who visited an outpatient clinic for HIV-infected patients at the Department of Infectious Disease, Huddinge Hospital, Stockholm, Sweden. A total of 72 of the original 78 questionnaires could be evaluated. Thirty respondents took part in the Stockholm Methadone Programme. The patients were asked to rank the importance of professional competence among the staff. The patients ranked competence in pain treatment highest followed by competence in somatic medical care. Lower ranked, but still perceived as important, was competence in psychiatric medical care and social welfare work. Experience in treatment of addiction was ranked as less important. It can be concluded that it is fruitful to ask IVDUs about their preferences concerning care.

AIDS-Related Opportunistic Infections↗
PubMed1995

An analysis of Hospital Discharge Index as a trauma data base.

STUDY OBJECTIVE: To document the validity of a Hospital Discharge Index (HDI) as a data base on injured patients. DESIGN: Patient information in trauma registries was compared with information in HDI. POPULATION: Injured patients admitted to trauma centers. METHODS: Patients in HDI were crossmatched with individuals in one or two trauma registries using deterministic matching techniques. Agreement regarding the presence and severity of injury was assessed. RESULTS: A comprehensive trauma registry from a level I trauma center and HDI agreed on the presence of an injury in each of 6 body regions over a range of kappa values from 0.17 to 0.71. The severity of injury score assigned by the two data bases demonstrated agreement over a range of intraclass correlation values from 0.12 to 0.82. CONCLUSION: HDI provides adequate information concerning injury for the majority of hospitalized patients, but was primarily limited by incomplete information. Efforts to improve HDI should focus on guidelines for data abstraction.

Hospital Information Systems↗
PubMed1995

[G1 cyclin degradation and cell differentiation in Saccharomyces cerevisiae].

The baker's yeast Saccharomyces cerevisiae can undergo pseudohyphal differentiation upon limited starvation for nitrogen. This differentiation is characterized by a hyperpolarized cell growth that gives rise to elongated cells. These elongated cells can form chains that penetrate an agar surface. The study of the grr1 mutant, affected in the degradation of the G1 cyclins, showed that the stabilization of Cln1 and Cln2 leads to a similar hyperpolarized cell growth. We suggest that G1 cyclin stability is a key element controlling cellular morphogenesis. Examination of G1 cyclin turnover during pseudohyphal growth strongly supports this hypothesis. Saccharomyces cerevisiae is thus an interesting model for studying the interconnections between cell cycle control and cellular differentiation.

Cell Differentiation↗
PubMed1994

Quantitative determination of CGP 53,437, a new HIV protease inhibitor, in plasma by high-performance liquid chromatography and fluorescence detection.

A specific and sensitive liquid chromatographic assay for CGP 53,437 (I), a potent HIV protease inhibitor, is described. The method is based on a deproteinization step, followed by a liquid-liquid extraction with diisopropyl ether. Then a deprotection step of the primary amine and derivatization using fluorescamine is performed. Chromatography is achieved by isocratic elution with a mobile phase of 63 mM borax buffer (pH 9)-acetonitrile (58:42, v/v). The flow-rate of the mobile phase is 1 ml/min. The derivatives of compound I and its internal standard CGP 54,451, II, fluoresce at 480 nm on excitation at 395 nm. The limit of quantitation which is the lowest concentration of the analyte that can be measured with a coefficient of variation and a deviation from theory of less than 20%, was 5 nmol/l plasma. The analyte is stable for at least seven months in spiked human plasma samples. It is also stable after freezing and thawing cycles. Different human plasma sources and plasma samples from three different species (dog, marmoset, and rat) were tested and no interferences from plasma constituents was observed.

Animals↗
PubMed1994

Site of accessory pathway block after radiofrequency catheter ablation in patients with the Wolff-Parkinson-White syndrome.

INTRODUCTION: Recent studies have demonstrated that the most common site of accessory pathway conduction block following the introduction of a premature atrial stimulus during atrial pacing is between the accessory pathway potential and the ventricular electrogram, consistent with block at the ventricular insertion of the accessory pathway. However, no prior study has evaluated the site of conduction block during radiofrequency catheter ablation procedures. Therefore, the objective of this study was to determine the site of conduction block after catheter ablation of accessory pathways by analyzing and comparing the local electrograms recorded before and after radiofrequency energy delivery at successful ablation sites. METHODS AND RESULTS: The electrograms evaluated in this study were obtained from 85 consecutive patients who underwent successful radiofrequency catheter ablation of a manifest accessory pathway. The 50 left free-wall accessory pathways were ablated using a ventricular approach and the 35 right free-wall or posteroseptal accessory pathways were ablated using an atrial approach. The characteristics of local electrograms recorded immediately before and immediately after successful ablation of the accessory pathway were determined in each patient. The site of accessory pathway block was determined by comparing the amplitude, timing, and morphology of the local electrograms at successful sites of radiofrequency catheter ablation before and after delivery of radiofrequency energy. A putative accessory pathway potential was present at the successful target site in 74 of the 85 patients (87%). Conduction block occurred between the atrial electrogram and the accessory pathway potential in 66 patients (78%) and between the accessory pathway potential and the ventricular electrogram in eight patients (9%). The site of block could not be determined in 11 patients (13%) in whom an accessory pathway potential was absent. Conduction block occurred most frequently between the atrial electrogram and the accessory pathway potential regardless of accessory pathway location. No electrogram parameter or accessory pathway characteristic was predictive of the site of conduction block. CONCLUSION: The results of this study demonstrate that conduction block occurs most frequently between the local atrial electrogram and the accessory pathway potential during radiofrequency catheter ablation of accessory pathways. This is true regardless of whether the accessory pathway is ablated from the atrial or ventricular aspect of the mitral or tricuspid annulus.

Adolescent↗
PubMed1994

[Resection anastomosis of the small intestine by celioscopy in swine. Comparative experimental study between manual and mechanical anastomosis].

Laparoscopic intestinal anastomosis is not very reliable and needs to be evaluate in an experimental model in animals before being performed in man. The purpose of this study was to evaluate the feasibility, efficacy and safety of manual anastomosis comparatively to the standard stapling suture. Twenty female pigs weighing 20 +/- 5 kg. were used for this study. A 5 cm ileal segment resection was performed under laparoscopy. The animals were assigned to 2 groups. Group I: 10 animals underwent end-to-end hand-swen anastomosis with Polyglactin 910, dec 1.5. Group II: 10 animals underwent side-to-side anastomosis using the Endo stapler. Operating time and anastomosis time were compared using the Mann-Whitney test for statistical analysis. On the 15th postoperative day, the animals were sacrificed and the anastomoses were evaluated. There was no operating death in the 2 groups. The operative time was significantly longer in group I than in group II (p < 0.01), with 180 +/- 40 min vs 49 +/- 25 min respectively. This difference was due to the anastomosis time of 130 +/- 40 min vs 16 +/- 6 min respectively (p < 0.01). There was 1 postoperative death related to fistula and peritonitis in group I and none in group II. The post-operative follow-ing showed 5 anastomotic leakages (4 in group I and 1 in group II) and 2 relative stenoses in group I. This study shows the simplicity and rapidity of performing stapling intestinal anastomosis under laparoscopy. Hand-sewn anastomosis is technically more difficult to perform under laparoscopy and requires a greater experience.

Anastomosis, Surgical↗