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Biomedical subjects

C Frank

Publications and source records attributed to C Frank.

At least 73 records · Page 4Linked to original sources
PubMed1998

[Virtual colonoscopy using CT and MRI].

PURPOSE: To evaluate experimentally and in patients the sensitivity and effective dose of virtual electron-beam tomography (EBT) colonoscopy for detecting small colon tumors and to compare the methods and results with virtual colonoscopy using spiral CT and MR imaging in a review of the literature. MATERIALS AND METHODS: Six polyps with diameters between 3 and 12 mm were created and randomly placed in resected pig colon. After distension with air, the pig colon was scanned with continuous volume scanning (CVS, 3 mm collimation) and a pitch of 0.4, 0.8 and 1.5. Twenty patients positive for the fecal blood test were examined after rectal CO2 insufflation and i.v. administration of 1 mg glucagon. A 13 s CVS scan was used to cover the entire colon within one breath-hold. 3D volume-rendered fly-throughs were evaluated by two independent radiologists. Effective dose equivalent was estimated using an Alderson phantom equipped with thermoluminescence dosimeters. RESULTS: In the tumor model, all polyps were detectable at a pitch of 1.5. A further reduction of the pitch ratio did not improve the conspicuity of the polyps. In patient studies, all tumors (n = 4) and polyps (n = 3) were correctly identified on 3D fly-throughs. Two false positive results were obtained. Effective dose equivalent was calculated at 3.2 mSv per scan. CONCLUSIONS: Our preliminary results indicate that virtual EBT colonoscopy holds promise for fast screening for colon polyps. The best technique for virtual colonoscopy (Spiral CT, EBT, MRI) has not yet been determined and the future role of virtual colonoscopy must still be defined.

Colonic Polyps↗
PubMed1998

Metabolism of aromatic aldehydes as cosubstrates by the acetogen Clostridium formicoaceticum.

When the acetogen Clostridium formicoaceticum was cultivated on mixtures of aromatic compounds (e.g., 4-hydroxybenzaldehyde plus vanillate), the oxidation of aromatic aldehyde groups occurred more rapidly than did O-demethylation. Likewise, when fructose and 4-hydroxybenzaldehyde were simultaneously provided as growth substrates, fructose was utilized only after the aromatic aldehyde group was oxidized to the carboxyl level. Aromatic aldehyde oxidoreductase activity was constitutive (activities approximated 0. 8 U mg-1), and when pulses of 4-hydroxybenzaldehyde were added during fructose-dependent growth, the rate at which fructose was utilized decreased until 4-hydroxybenzaldehyde was consumed. Although 4-hydroxybenzaldehyde inhibited the capacity of cells to metabolize fructose, lactate or gluconate were consumed simultaneously with 4-hydroxybenzaldehyde, and lactate or aromatic compounds lacking an aldehyde group were utilized concomitantly with fructose. These results demonstrate that (1) aromatic aldehydes can be utilized as cosubstrates and have negative effects on the homoacetogenic utilization of fructose by C. formicoaceticum, and (2) the consumption of certain substrates by this acetogen is not subject to catabolite repression by fructose.

Benzaldehydes↗
PubMed1998

Plasma catecholamine levels following tracheal and intravenous epinephrine administration in swine.

We compared plasma epinephrine levels after three different tracheal epinephrine application techniques and intravenous injection in male and female anesthetized and paralyzed domestic pigs. Epinephrine was administered intravenously (10 microg/kg) (group i.v.) or tracheally (100 microg/kg) either by direct injection into the upper end of the tracheal tube (group Tube), via a suction tube placed into the bronchial system (group Catheter) or using an EDGAR tube (group EDGAR), each group: n = 8. Arterial plasma samples were drawn before and 0.5, 1, 1.5, 2, 2.5, 3, 4, 5, 6, 7 and 10 min after epinephrine administration. Plasma concentrations of epinephrine were measured with high pressure liquid chromatography using electrochemical detection. Analysis was performed by regression analysis for correlated data. Total plasma epinephrine concentrations showed a significant increase within 0.5 min in all groups. However, peak plasma epinephrine levels in group i.v. were significantly higher than in tracheal groups, while no differences between tracheal groups over the time were found. We conclude that in swine with spontaneous circulation tracheal instillation techniques using special devices such as suction tubes or EDGAR tubes result in onset and peak plasma epinephrine levels equivalent to those after direct injection into the upper end of the tracheal tube.

Animals↗
PubMed1998

Increased spontaneous in vitro apoptosis in double negative T cells of humans with a fas/apo-1 mutation.

We describe a 17 year old patient suffering from Canale-Smith syndrome (CSS) including chronic lymphadenopathy, splenomegaly, hypergammaglobulinemia and recurrent Coombs positive hemolytic crises. The parents are not consanguine, all other family members including two brothers are healthy. Peripheral blood mononuclear cells of the patient showed an increased rate of CD3 positive, CD4/CD8 double negative T-lymphocytes. In vitro assays showed these cells to have an increased rate of spontaneous apoptosis. Though expression of Fas/Apo-1 (CD95) and Fas-ligand (FasL) was detected on RNA- and protein level we found Fas/Apo-1 mediated apoptosis being significantly reduced. Sequencing of the fas/apo-1 gene proved the patient RT and his father to carry a point mutation at position 804 located in exon 9 (death domain) leading to an amino acid substitution. For developing of CSS, a fas/apo-1 mutation seems to be necessary but not sufficient. An additional independent mechanism must be involved in the pathogenesis of human lpr<-phenotype.

Adolescent↗
PubMed1998

Human sleep under the influence of pulsed radiofrequency electromagnetic fields: a polysomnographic study using standardized conditions.

To investigate the influence of radiofrequency electromagnetic fields (EMFs) of cellular phone GSM signals on human sleep electroencephalographic (EEG) pattern, all-night polysomnographies of 24 healthy male subjects were recorded, both with and without exposure to a circular polarized EMF (900 MHz, pulsed with a frequency of 217 Hz, pulse width 577 micros, power flux density 0.2 W/m2. Suppression of rapid eye movement (REM) sleep as well as a sleep-inducing effect under field exposure did not reach statistical significance, so that previous results indicating alterations of these sleep parameters could not be replicated. Spectral power analysis also did not reveal any alterations of the EEG rhythms during EMF exposure. The failure to confirm our previous results might be due to dose-dependent effects of the EMF on the human sleep profile.

Adolescent↗
PubMed1998

Dementia workup. Deciding on laboratory testing for the elderly.

OBJECTIVE: To review Canadian Consensus Conference on the Assessment of Dementia (CCCAD) guidelines for laboratory evaluation of dementia, and to make recommendations to family physicians based on these guidelines and other literature. DATA SOURCES: English-language data sources from 1992 to March 1997 were searched on MEDLINE using the MeSH headings dementia, dementia/diagnosis, and cognition. Key words relating to specific laboratory tests or conditions, such as neurosyphilis or vitamin B12, were also used. STUDY SELECTION: Original research articles using prospective and retrospective methods were accepted. Articles reviewing the general investigation of potentially reversible dementia were included, as were articles looking at the sensitivity, specificity, and utility of investigations for specific conditions causing dementia. SYNTHESIS: Family physicians are not always aware of CCCAD recommendations for the investigation of dementia. There was C-level evidence for use of CCCAD core investigations (complete blood count and electrolyte, glucose, calcium, and thyroid levels) and for tests to be done "when the clinical situation warrants" (B12 levels, computed tomography scan of the head, and testing for syphilis). CONCLUSIONS: The CCCAD guidelines were supported by most literature on the workup of dementia. Prospective cohort studies suggest use of clinical judgment in ordering laboratory investigations. No controlled trials were available, and most recommendations arose from consensus rather than from research evidence. The prevalence of reversible dementias is likely lower than previously believed, which further supports a selective approach to investigations. Identification of reversible causes and exacerbating factors is still the goal.

Aged↗
PubMed1997

Differential pathophysiological mechanisms of reduced P300 amplitude in schizophrenia and depression: a single trial analysis.

In order to address basic mechanisms behind a reduced averaged P300 wave in schizophrenia and depression, 17 unmedicated schizophrenic and 11 unmedicated depressive subjects were tested in an 'oddball paradigm' against healthy controls matched for gender and age. The amplitude distributions of single trials' maximum positive deflections after stimulation (P300) for both target and nontarget stimuli were determined, which served as a basis for calculating the discrimination index d'. This index characterizes differences in the electrophysiological responses to target and nontarget stimuli of a subject being engaged in a discrimination task. As a main result d' was significantly lower for schizophrenics than for their controls. Directly compared to depressive subjects, schizophrenics also depicted a statistically significant decrease of the discrimination index, which could not be explained by differences in age. Although the averaged P300 signals did not show any significant differences between the two diagnostic groups, the approach of calculating d' on the basis of single trial analysis differentiated between schizophrenics and depressives. In conclusion, schizophrenic patients revealed different functional features when generating event-related potentials in an 'oddball paradigm' compared to healthy controls and depressives.

Adult↗
PubMed1997

Norepinephrine induced growth and expression of virulence associated factors in enterotoxigenic and enterohemorrhagic strains of Escherichia coli.

The small intestine is richly innervated by the sympathetic nervous system. High concentrations of monoamines, most notably norepinephrine, are found throughout the various intestinal layers. In order to determine whether norepinephrine is capable of influencing bacterial pathogenesis, the growth and production of virulence factors in ETEC and EHEC were examined in a physiologically relevant medium utilizing very low initial bacterial inoculums to more closely mimie in vivo conditions. The growth of ETEC strain B44 and the production of the K99 pilus adhesin on a protein equivalent basis was greatly increased in the presence of norepinephrine. Growth of EHEC O157:H7 was also increased in norepinephrine containing medium as well as production of SLT-I and SLT-II. The ability of norepinephrine to increase both bacterial growth and expression of virulence factors was shown to be non-nutritional in nature. Given the abundant adrenergic innervation in the small intestine, these in vitro results suggest that the neurohumoral environment of the host may play a role in bacterial growth and expression of virulence factors.

Antigens, Surface↗
PubMed1997

Prolonged oxygen debt after abdominal aortic surgery.

OBJECTIVE: The aim of the study was to investigate whether oxygen consumption and carbon dioxide production changed in the early postoperative period in the same manner in patients who underwent coronary artery bypass graft (CABG) surgery or abdominal aortic surgery (AAS). DESIGN: Prospective clinical study. SETTING: Single community hospital. PARTICIPANTS: Twenty-four patients (ASA II to III) who underwent elective abdominal aortic surgery and 49 patients (NYHA II, III) who underwent elective CABG surgery. INTERVENTIONS: In the ICU, oxygen consumption (VO2), carbon dioxide production (VCO2), and respiratory quotient (RQ) were continuously monitored with an indirect calorimetric device. Hemodynamic and metabolic parameters were measured during the first 3 hours. MEASUREMENTS AND MAIN RESULTS: In the early postoperative course, VO2 and VCO2 in the AAS group were significantly higher (p < 0.001), and the RQ was significantly lower during the first 90 minutes (p < 0.001). In the AAS patients, VO2 decreased with the postoperative increase of body temperature; whereas in the CABG patients, VO2 slightly increased. CONCLUSIONS: The high VO2 in the AAS patients observed during the early postoperative course can be explained by an oxygen debt that occurred as a result of clamping the aorta. It was presumed that the repayment of the debt was delayed and extended to the ICU stay because of thermoregulatory vasoconstriction. Abnormally low RQ values are probably a clue to repayment of an oxygen debt.

Adult↗
PubMed1997

The shear behaviour of the rabbit medial collateral ligament.

This study was conducted to determine whether load is transmitted via shear through the matrix between ligament fibres rather than solely as tension in the fibres. Thirty-six rabbit medial collateral ligaments were subjected to uniaxial tension tests. Twenty-four of these ligament complexes were incised laterally to create longitudinal shear planes, while the remaining 12 complexes served as controls. Data were used in conjunction with finite element models to determine how shear transfer, if any, occurred in the ligament. Non-linear, anisotropic, plane stress finite element models were able to simulate the non-linear structural behaviour shown by uncut control ligaments under normal tensile testing. The finite element models were also able to reproduce the ligament load deformation behaviour observed in the shear tests. Results indicated that some load was transferred between the collagen fibres and other constituents in the ground substance of these ligaments and possibly also through fibres missed during the cutting procedure. The exact manner in which the load was transmitted remains unclear and requires further investigation and quantification.

Animals↗
PubMed1997

The influence of lorazepam upon pre- and poststimulus EEG during sleep in man.

Enhancement of beta power in the spontaneous EEG under the influence of benzodiazepine medication is a well known phenomenon under waking conditions as well as during sleep. On the other hand, in certain frequency bands EEG activity following external stimulation is also enhanced. Therefore, the question arises what relationship exists between pre- and poststimulus EEG under the influence of benzodiazepines. Is an augmentation of beta activity during benzodiazepine medication further enhanced when external stimulation is applied? In order to address this question we compared the spectral power of pre- and poststimulus EEG under 2.5 mg lorazepam during sleep with placebo conditions. The hypothesis tested was that of Basar (1980): if the beta power is high prior to the stimulation, no further enhancement following stimulation is observed. Our results confirm the hypothesis during sleep stages II and III. At the present time it is unclear whether this effect might be dose-dependent. In any case, the investigation presented here has furnished additional information on the mechanisms by which benzodiazepines alter the brain's electrical activity.

Acoustic Stimulation↗
PubMed1997

Sporomusa silvacetica sp, nov., an acetogenic bacterium isolated from aggregated forest soil.

Sporomusa silvacetica sp. nov. DG-1T (= DSMZ 10669T) (T = type strain) was isolated from well-drained, aggregated forest soil (pH 6.0) in east-central Germany. The cells were obligately anaerobic, slightly curved rods and were motile by means of laterally inserted flagella on the concave side of each cell. Typical cells were approximately 3.5 by 0.7 micron. Cells stained weakly gram positive, but thin sections revealed a complex multilayer cell wall. Spores were spherical and distended the sporangia. Growth and substrate utilization occurred with ferulate, vanillate, fructose, betaine, fumarate, 2,3-butanediol, pyruvate, lactate, glycerol, ethanol, methanol, formate, and H2-CO2. With most substrates, acetate was the primary reduced end product and was produced in stoichiometries indicative of an acetyl-coenzyme A pathway-dependent metabolism. Fumarate was dismutated to succinate and acetate. Methoxyl and acrylate groups of various aromatic compounds were O-demethylated and reduced, respectively. Yeast extract was not required for growth. Cells grew optimally at approximately 30 degrees C and pH 6.8; under these conditions and with fructose as the substrate, the doubling time was approximately 14 h. The lowest temperature that supported growth was between 5 and 10 degrees C. The carbon monoxide dehydrogenase and hydrogenase activities were approximately 9 and 102 mumol min-1 mg of protein-1, respectively. A type b cytochrome was detected in the membrane. The G + C content was approximately 43 mol%. Phylogenetic analysis of the 16S ribosomal DNA indicated that DG-1T was most closely related to members of the genus Sporomusa in the Clostridium subphylum of the gram-positive bacteria.

Base Composition↗
PubMed1997

p53 and WAF1 are induced and Rb protein is hypophosphorylated during cell growth inhibition by the thymidylate synthase inhibitor ZD1694 (Tomudex).

In a previous study, we found that treatment of HCT-8 cells with ZD1694, a specific antifolate-based thymidylate synthase inhibitor, resulted in DNA fragmentation. In this study, we have demonstrated the dose- and time-dependent induction of DNA fragmentation accompanied by elevation of p53 and WAF1 protein expression by ZD1694. WAF1 mRNA showed a time-dependent increase, whereas p53 mRNA was not found to be significantly overexpressed. The initial increase in WAF1 mRNA was detected at 4 hr, but increased WAF1 protein expression was detected 8-24 hr after a 2-hr exposure. The amount of total and hypophosphorylated pRb seems to be rising greatly after ZD1694 exposure. The effects of ZD1694 on the expression of E2F1 and formation of the E2F1-Rb complex were investigated after a 2-hr drug exposure (IC90). The results showed a time-dependent decrease in E2F1 mRNA and protein expression; an increase in the abundance of the E2F-Rb complex could be demonstrated beginning 4 hr after drug exposure by a gel shift assay. Kinetic analysis showed increased availability of hypophosphorylated pRb for inhibition of E2F, which could indirectly result from WAF1-induced inhibition cyclin-dependent kinase activity. Whereas thymidylate synthase inhibition by ZD1694 was rapid in onset and maintained for at least 24 hr after drug treatment, drug-induced cellular growth inhibition was significant 24 hr after drug exposure. The increased abundance of hypophosphorylated pRb and binding to transcription factor E2F-1 is consistent with ZD1694-induced cell growth inhibition in HCT-8 cells. Therefore, the observed effect on downstream events after effective inhibition of thymidylate synthase may offer the critical determinants of response to ZD1694.

Adenocarcinoma↗
PubMed1997

Detection of restricted junctional diversity of peripheral T cells in SLE patients by spectratyping.

Analysis of somatic mutations revealed that anti-double-stranded DNA (dsDNA) autoantibodies from patients with systemic lupus erythematosus (SLE) share features of a T cell dependent, antigen driven immune response. Therefore we analysed the length diversity of the complementarity determining region 3 (CDR3) of T cell receptor (TCR) by high resolution gel electrophoresis of 16 V beta family specific RT PCR products (spectratyping). To enable statistical analysis we developed a quantitative scoring method for the histograms. We investigated 16 V beta gene families in peripheral T cells of SLE patients (n = 9) with active (n = 5) and inactive (n = 4) disease as well as normal healthy blood donors (NHD; n = 9). Analysis of TCR V beta spectratypes (active SLE, n = 59; inactive SLE, n = 51 and NHD n = 97) revealed statistically significant differences of CDR3 length distribution between SLE patients and NHD (P < 0.0001 (active SLE/NHD) and P = 0.0034 (inactive SLE/NHD). These results suggest that spectratyping is able to detect clonal activation of peripheral T cells which correlates to disease activity in SLE patients. We conclude that peripheral T cells from SLE patients display features of a secondary antigen driven immune response.

Adolescent↗
PubMed1997

Collagen fibril diameters in the rabbit medial collateral ligament scar: a longer term assessment.

Previous transmission electron microscopic investigations of collagen fibril diameters in rabbit medial collateral ligament (MCL) scars have indicated a homogeneous population of small fibrils for the first 40 weeks of healing. In this study, four 8 mm MCL gap scars were studied at 78 weeks of healing and another three at 104 weeks. Results showed increased heterogeneity in the distribution of fibril diameters in all scars, with the appearance of progressively slightly larger fibrils in 78 and 104 week specimens. All longer term scars still contained roughly 90% small fibrils plus some "patches" of larger fibrils, but there was considerable variation between animals in these proportions. No scar contained the fibril populations typical of uninjured adult rabbit MCLs. These results suggest slow but on-going collagen fibril turnover and remodeling in this gap healing rabbit MCL model via currently unidentified mechanisms.

Animals↗
PubMed1997

Medical management of intestinal obstruction in terminal care.

OBJECTIVE: To review the evidence on the effectiveness of medical management of bowel obstruction for patients with advanced cancer and to summarize treatment options for home and hospital care. DATA SOURCES: Articles were identified by searching MEDLINE. STUDY SELECTION: Research articles published between 1973 and 1995 on the surgical and medical management of bowel obstruction in patients with advanced cancer were identified. Seven original research articles on medical management were identified and all were reviewed and critically appraised. Given the small number of original papers in this field, studies using prospective and retrospective methodology were included. Articles looking only at the use of percutaneous gastrostomy tubes and subcutaneous hydration were used in the formulation of treatment recommendations but were not critically reviewed. A critical appraisal of the surgical literature was not undertaken. SYNTHESIS: Recommendations regarding medical management of bowel obstruction were based on strength of evidence for improving symptoms with pharmacologic treatment. The few clinical trials were uncontrolled trials with small samples. The trials show improvement of symptom control with pharmacologic management using morphine, anticholinergics, major tranquilizers, corticosteroids, and somatostatin analogues. Intravenous hydration was unnecessary for most patients. Percutaneous gastrostomy tubes are effective for patients with proximal intestinal obstruction and intractable vomiting. CONCLUSIONS: Pharmacologic management and percutaneous gastrostomy for intractable vomiting and hypodermoclysis or oral fluids for hydration can control symptoms without surgery or nasogastric tubes.

Analgesics, Opioid↗
PubMed1997

The effectiveness of patient verbalization on informed consent.

OBJECTIVE: To determine if preoperative patient verbalization of the risks and benefits of anterior cruciate ligament (ACL) reconstruction enhances understanding of the risks and benefits of that procedure. DESIGN: A randomized clinical trial. SETTING: A referral-based outpatient sport medicine clinic. SUBJECTS: Twenty patients from the general population with clinically diagnosed ACL tears requiring elective reconstruction surgery were randomly assigned to 2 groups. Twelve patients who made up a control group received a standard surgical consultation, consisting of knee models, diagrams, open dialogue and informed consent to surgery. Eight patients in the experimental group were exposed to the same surgical consultation and were required to accurately verbalize the associated risks and benefits before operation. One month after informed consent was obtained, patients answered 3 questions about the risks and benefits of ACL reconstruction. INTERVENTION: ACL reconstruction. MAIN OUTCOME MEASURES: A 3-question questionnaire, addressing 2 risks and 1 benefit of ACL reconstruction. MAIN RESULTS: Patients in the experimental group were able to answer all 3 questions correctly. In the control group, 4 patients answered all 3 questions correctly, but 1 patient answered all 3 questions incorrectly, and 7 patients answered 1 question incorrectly. There was a statistically significant difference (p = 0.03) between the control group and the experimental group. CONCLUSION: Patients who verbalized the risks and benefits during their surgical consultation demonstrated a significantly greater understanding of the risks and benefits of an ACL reconstruction procedure.

Anterior Cruciate Ligament↗