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Biomedical subjects

G Frank

Publications and source records attributed to G Frank.

At least 19 recordsLinked to original sources
PubMed2004

Endoscopic treatment of encephaloceles of the lateral wall of the sphenoid sinus.

OBJECTIVE: The suitability of the endoscopic approach for the treatment of an encephalocele of the lateral wall of the sphenoid is discussed. This is a retrospective review of 4 cases diagnosed with temporosphenoidal encephalocele and having a history of CSF leak who were surgically treated using an endoscopic endonasal approach between January 2001 and June 2002 at the Department of Otolaryngology of Sant'Orsola-Malpighi University Hospital and the Department of Neurosurgery at Bellaria Hospital in Bologna. METHODS: Three patients were female between 48 and 73 years of age (mean: 61 years). All patients had suffered from a CSF leak for 5 months to 18 years. None of the patients had a past medical history of head trauma. A fourth patient had undergone a previous microscopic approach for a previously misdiagnosed CSF leak wrongly ascribed to an empty sella. Three patients underwent an ethmoid-pterygo-sphenoidal endoscopic approach (EPSEA), while the patient who had undergone previous microscopic surgery, was treated using a transnasal transsphenoidal endoscopic approach. RESULTS: The follow-up of the patients ranged from 10 to 26 months (mean: 18 months) and no case of a recurrent CSF leak was observed postoperatively. CONCLUSIONS: In our report, the endoscopic approach was a useful tool for the treatment of encephaloceles of the lateral wall of the sphenoid sinus. In skilled hands, this technique permits both the resection of the encephalocele and the subsequent reconstruction of the defect also with a low rate of morbidity.

Aged↗
PubMed2004

Capnocytophaga spp. brain abscess in an immunocompetent host: problems in antimicrobial chemotherapy and literature review.

The fourth case report of a brain abscess due to the fastidious Gram-negative organism Capnocytophaga spp. is described and discussed on the grounds of clinical, microbiological, and therapeutic evidence. A probable origin from a cat bite and/or an underlying severe mandibulary granuloma is suspected. Due to lack of clinical and neuroradiological response to neurosurgery and a combination of imipenem-amikacin-clindamycin-fluconazole, second-line empiric llnezolid treatment proved rapidly successful, in the absence of further microbial isolations. In vitro antimicrobial susceptibility testing is often unpredictable for Capnocytophaga spp., and agents usually active on Gram-positive organisms may also be effective, both in vitro and in vivo. Due to its favorable brain penetration and its dual mode of administration, linezolid may be an alternative option for patients with multiple risk factors, brain abscess of suspected polymicrobial origin, and lack of response to empiric or culture-driven therapeutic attempts.

Adult↗
PubMed2003

Combined use of transesophageal ECHO and fluoroscopy for the placement of left ventricular pacing leads via the coronary sinus.

Biventricular pacing is an emerging technology for treatment of congestive heart failure. Left ventricular leads are most commonly placed through the coronary sinus (CS) into an epicardial coronary vein. Cannulation of the CS can be difficult and standard guiding catheters have a tendency to displace during lead advancement. This study found that transesophageal echocardiography facilitated CS cannulation in complex cases requiring antecedent lead extraction.

Echocardiography, Transesophageal↗
PubMed2002

Eating-related concerns, mood, and personality traits in recovered bulimia nervosa subjects: a replication study.

OBJECTIVE: Limited data suggest that eating-related concerns and behaviors, disturbances in mood, and altered temperament persist following recovery from bulimia nervosa (BN). METHOD: In order to replicate and extend such findings, 11 women who were long-term recovered from BN (>1 year with no binging, purging, or restricting behaviors, normal weight, and regular menstrual cycles) were compared with 15 healthy volunteer women on the Eating Disorders Invertory-2 (EDI-2), the Beck Depression Inventory, the State Trait Anxiety Inventory, and the Multidimensional Personality Questionnaire (MPQ). RESULTS: Compared with the control women, the recovered BN women showed elevated levels of the EDI-2 subscales of Drive for Thinness, Body Dissatisfaction, Ineffectiveness, Perfectionism, and Social Insecurity, greater depression and anxiety, elevated levels of the MPQ Stress Reaction dimension and the higher-order factor of Negative Emotionality, and lower levels of the MPQ Well Being and Closeness dimensions. DISCUSSION: Core eating and weight-related concerns, dysphoric affect, social discomfort, and personality traits indicative of perfectionism persist following long-term recovery from BN.

Adult↗
PubMed2002

Ultrasound monitoring of temperature change during radiofrequency ablation: preliminary in-vivo results.

Radiofrequency (RF) ablation is an interstitial focal ablative therapy that can be used in a percutaneous fashion and permits in situ destruction of hepatic tumors. However, local tumor recurrence rates after RF ablative therapy are as high as 34% to 55%, which may be due in part to the inability to monitor accurately temperature profiles in the tissue being ablated, and to visualize the subsequent zone of necrosis (thermal lesion) formed. The goal of the work described in this paper was to investigate methods for the real-time and in vivo monitoring of the spatial distribution of heating and temperature elevation to achieve better control of the degree of tissue damage during RF ablation therapy. Temperature estimates are obtained using a cross-correlation algorithm applied to RF ultrasound (US) echo signal data acquired at discrete intervals during heating. These temperature maps were used to display the initial temperature rise and to continuously update a thermal map of the treated region. Temperature monitoring is currently performed using thermosensors on the prongs (tines) of the RF ablation probe. However, monitoring the spatial distribution of heating is necessary to control the degree of tissue damage produced.

Animals↗
PubMed2002

Elastographic imaging using a handheld compressor.

Elastography is an emerging imaging modality that allows noninvasive imaging of tissue stiffness changes and stiffness values associated with pathology or as a result of therapy. However, many currently-used systems for elastography rely on a fixed geometry transducer and compressor system for imaging. This configuration is disadvantageous for imaging difficult-to-reach regions that are currently accessible with conventional ultrasound. In this paper, we describe a handheld, portable stepper motor controlled system for elastography. This system may reduce motion and jitter errors that are prevalent in completely 'freehand elastography' that employs hand-induced compressions using the transducer. The latter also requires collection of large amounts of data and use of strain estimation algorithms that may not be sensitive to phase changes or use additional preprocessing to minimize decorrelation effects. The stepper motor controlled handheld system provides controlled compressions and synchronized data acquisition. Our technique yields elastograms of a low-contrast phantom that have contrast levels and contrast-to-noise ratios that are comparable to those obtained with a fixed geometry system.

Animals↗
PubMed2002

Temperature dependence of ultrasonic propagation speed and attenuation in canine tissue.

Previously reported data on the temperature dependence of propagation speed in tissues generally span only temperature ranges up to 60 degrees C. However, with the emerging use of thermal ablative therapies, information on variation in this parameter over higher temperature ranges is needed. Measurements of the ultrasonic propagation speed and attenuation in tissue in vitro at discrete temperatures ranging from 25 to 95 degrees C was performed for canine liver, muscle, kidney and prostate using 3 and 5 MHz center frequencies. The objective was to produce information for calibrating temperature-monitoring algorithms during ablative therapy. Resulting curves of the propagation speed vs. temperature for these tissues can be divided into three regions. In the 25-40 degrees C range, the speed of sound increase rapidly with temperature. It increases moderately with temperature in the 40-70 degrees C range, and it then decreases with increasing temperature from 70-95 degrees C. Attenuation coefficient behavior with temperature is different for the various tissues. For liver, the attenuation coefficient is nearly constant with temperature. For kidney, attenuation increases approximately linearly with temperature, while for muscle and prostate tissue, curves of attenuation vs. temperature are flat in the 25-50 degrees C range, slowly rise at medium temperatures (50-70 degrees C), and level off at higher temperatures (70-90 degrees C). Measurements were also conducted on a distilled degassed water sample and the results closely follow values from the literature.

Animals↗
PubMed2001

Stimulation of eukaryotic flap endonuclease-1 activities by proliferating cell nuclear antigen (PCNA) is independent of its in vitro interaction via a consensus PCNA binding region.

Interaction between human flap endonuclease-1 (hFEN-1) and proliferating cell nuclear antigen (PCNA) represents a good model for interactions between multiple functional proteins involved in DNA metabolic pathways. A region of 9 conserved amino acid residues (residues Gln-337 through Lys-345) in the C terminus of human FEN-1 (hFEN-1) was shown to be responsible for the interaction with PCNA. Our current study indicates that 4 amino acid residues in hFEN-1 (Leu-340, Asp-341, Phe-343, and Phe-344) are critical for human PCNA (hPCNA) interaction. A conserved PCNA interaction motif in various proteins from assorted species has been defined as Q(1)X(2)X(3)(L/I)(4)X(5)X(6)F(7)(F/Y)(8), although our results fail to implicate Q(1) (Gln-337 in hFEN-1) as a crucial residue. Surprisingly, all hFEN-1 mutants, including L340A, D341A, F343A, and F344A, retained hPCNA-mediated stimulation of both exo- and flap endonuclease activities. Furthermore, our in vitro assay showed that hPCNA failed to bind to the scRad27 (yeast homolog of FEN-1) nuclease. However, its nuclease activities were significantly enhanced in the presence of hPCNA. Four additional Saccharomyces cerevisiae scRad27 mutants, including multiple alanine mutants and a deletion mutant of the entire PCNA binding region, were constructed to confirm this result. All of these mutants retained PCNA-driven nuclease activity stimulation. We therefore conclude that stimulation of eukaryotic hFEN-1 nuclease activities by PCNA is independent of its in vitro interaction via the PCNA binding region.

Amino Acid Motifs↗
PubMed2001

Reciprocal electromechanical properties of rat prestin: the motor molecule from rat outer hair cells.

Cochlear outer hair cells (OHCs) are responsible for the exquisite sensitivity, dynamic range, and frequency-resolving capacity of the mammalian hearing organ. These unique cells respond to an electrical stimulus with a cycle-by-cycle change in cell length that is mediated by molecular motors in the cells' basolateral membrane. Recent work identified prestin, a protein with similarity to pendrin-related anion transporters, as the OHC motor molecule. Here we show that heterologously expressed prestin from rat OHCs (rprestin) exhibits reciprocal electromechanical properties as known for the OHC motor protein. Upon electrical stimulation in the microchamber configuration, rprestin generates mechanical force with constant amplitude and phase up to a stimulus frequency of at least 20 kHz. Mechanical stimulation of rprestin in excised outside-out patches shifts the voltage dependence of the nonlinear capacitance characterizing the electrical properties of the molecule. The results indicate that rprestin is a molecular motor that displays reciprocal electromechanical properties over the entire frequency range relevant for mammalian hearing.

Amino Acid Sequence↗
PubMed2001

Characterization of N-glycans from mouse brain neural cell adhesion molecule.

The N-glycosylation pattern of the neural cell adhesion molecule (NCAM), isolated from brains of newborn mice, has been analyzed. Following digestion with trypsin, generated glycopeptides were fractionated by serial immunoaffinity chromatography using immobilized monoclonal antibodies specifically recognizing polysialic acid (PSA) units or the HNK1-carbohydrate epitope. Subsequent analyses of the resulting (glyco)peptides by Edman degradation and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) revealed polysialylated glycans to be exclusively linked to glycosylation sites 5 (Asn(431)) and 6 (Asn(460)), whereas glycans carrying the HNK1-epitope could be assigned to sites 2 (Asn(297)), 5, 6, and, to a lesser extent, site 3 (Asn(329)). PSA-, HNK1-, and non-PSA/HNK1-glycan fractions were characterized by carbohydrate constituent and methylation analyses as well as MALDI-TOF-MS in conjunction with chromatographic fractionation techniques. The results revealed that the core structures of PSA-glycans represented predominantly fucosylated, partially sulfated 2,6-branched isomers of triantennary as well as tetraantennary complex-type glycans, whereas carbohydrate chains bearing the HNK1-epitope were dominated by diantennary species carrying in part bisecting GlcNAc residues. Non-PSA/HNK1-glycans exhibited a highly heterogeneous pattern of partially truncated, mostly diantennary structures being characterized by the presence of additional fucose, bisecting GlcNAc and/or sulfate residues. In conclusion, our results revealed that the glycosylation pattern of murine NCAM displays high structural and regional selectivity, which might play an important role in controlling the biological activities of this molecule.

Amino Acid Sequence↗
PubMed2001

Bioethics in a different tongue: the case of truth-telling.

After a survey of 800 seniors from four different ethnic groups showed that Korean-American and Mexican-American subjects were much less likely than their European-American and African-American counterparts to believe that a patient should be told the truth about the diagnosis and prognosis of a terminal illness, we undertook an ethnographic study to look more deeply at attitudes and experiences of these respondents. European-American and African-American respondents were more likely to view truth-telling as empowering, enabling the patient to make choices, while the Korean-American and Mexican-American respondents were more likely to see the truth-telling as cruel, and even harmful, to the patients. Further differences were noted in how the truth should be told and even in definitions of what constitutes "truth" and "telling." Clinical and bioethics professionals should be aware of how their cultural and economic backgrounds influence the way they perceive ethical dilemmas and remember to make room for the diverse views of the populations they serve.

Aged↗
PubMed2001

Identification and characterization of an aromatic amino acid decarboxylase from the filarial nematode, Dirofilaria immitis.

A novel secreted aromatic amino acid decarboxylase-like molecule was identified in the excretory/secretory products of L3/L4 larvae as well as in an extract of adult Dirofilaria immitis. The secretion of the enzyme was developmentally regulated. Peak enzyme activities were detected in the culture medium before and after the molting of L3 larvae in vitro. The enzyme was purified from D. immitis adult extracts and the excretory/secretory products of L3/L4 larvae using different chromatographic methods followed by isoelectric focusing and SDS-PAGE. The enzyme has a molecular mass of 48 kDa and a pI of 5.6, and shows a specific enzymatic activity towards the aromatic amino acid substrates phenylalanine, tyrosine and tryptophan. The enzyme's activity did not show an absolute requirement for exogenous pyridoxal-5-phosphate. However, addition of pyridoxal-5-phosphate at 5 microM in the reaction increased the enzyme activity greatly. The enzyme had the ability to catalyze the formation of dopamine from L-dopa. Studies on the effects of inhibitors on the enzyme activity showed that the enzyme was sensitive to Pefabloc and p-chloromercuribenzoic acid, but not to diisopropyl flurophosphate. The Km values of the enzyme for H-Phe-AMC, H-Tyr-AMC and H-Trp-AMC were calculated to be 32.1 microM, 35.1 microM and 29.1 microM, respectively.

Animals↗
PubMed2001

Extended transsphenoidal approach.

The authors have developed an extended transsphenoidal approach with submucosal posterior ethmoidectomy for resection of tumors located in the cavernous sinus or the suprasellar region that are difficult to remove via the conventional transsphenoidal approach. Surgery was performed using this approach in 14 patients with large pituitary adenomas, three patients with craniopharyngiomas, and one patient with a meningioma of the tuberculum sellae. The submucosal dissection of the nasal septum used in the conventional transsphenoidal approach was extended to the superior lateral wall of the nasal cavity to expose the bony surface of the superior turbinate lying under the nasal mucosa. Submucosal posterior ethmoidectomy widened the area visualized through the conventional transsphenoidal approach both superiorly and laterally. This provided a safer and less invasive access to lesions in the cavernous sinus or the suprasellar region through the sphenoid sinus. Using this approach the authors encountered no postoperative complications, such as olfactory disturbance, cranial nerve palsy, or arterial injury. In this article the authors present the surgical methods used in this approach.

Brain Neoplasms↗