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Biomedical subjects

P Herman

Publications and source records attributed to P Herman.

At least 55 records · Page 3Linked to original sources
PubMed2000

Expression of NMDA, AMPA and GABA(A) receptor subunit mRNAs in the rat auditory brainstem. I. Influence of early auditory deprivation.

Impact of early post-natal deafening on auditory pathways was investigated in newborn rats deafened by daily amikacin injections from P7 to P16 inducing a complete destruction of the organ of Corti. The expression of mRNAs encoding N-methyl-D-aspartate (NMDA), alpha-amino-3-hydroxy-5-methyl-4-isoxazole (AMPA) and gamma-aminobutyric acid type A (GABA(A)) receptor subunits was then studied by in situ hybridization in the dorsal and ventral cochlear nucleus and in the central nucleus of the inferior colliculus (CNIC). Early post-natal deafening decreased bilaterally the expression of mRNAs encoding NR1, NR2a, NR2b and flop isoforms of AMPA receptors. On the contrary, it increased the expression of mRNAs encoding some GABA(A) subunits (alpha1, beta1, gamma2) and flip isoforms of AMPA receptors. These changes were more pronounced in cochlear nuclei than in CNIC. They suggest that auditory sensation is essential in the normal development of central auditory pathways.

Amikacin↗
PubMed2000

Expression of NMDA, AMPA and GABA(A) receptor subunit mRNAs in the rat auditory brainstem. II. Influence of intracochlear electrical stimulation.

We investigated the effects of intracochlear electrical stimulation (ICES) on auditory pathways of neonatal rat deafened by daily amikacin injections. Expression of mRNAs encoding ionotropic glutamate receptor subunits such as alpha-amino-3-hydroxy-5-methyl-4-isoxazole (AMPA) and N-methyl-D-aspartate (NMDA), and gamma-aminobutyric acid type A (GABA(A)) receptor subunits was assessed by in situ hybridization in the dorsal (DCN) and the ventral cochlear nucleus (VCN) and in the central nucleus of the inferior colliculus (CNIC). After 15 days of daily unilateral ICES, the expressions of NR1, NR2b and NR2c subunits of NMDA receptor, that of GluRA, B, C, D flop isoforms of AMPA receptor and that of some GABA(A) subunits (alpha1, beta1, gamma1, gamma2) were increased bilaterally in the DCN, VCN and the CNIC. These changes last over a week after stimulation for only NR1 and NR2c. These modifications might be related to long lasting synaptic plasticity of brainstem auditory pathways. As far as analogy to deaf children can be made, early electrical stimulation might be of interest to maintain neuronal networks.

Animals↗
PubMed2000

Alternative technique of laparoscopic hepaticojejunostomy for advanced pancreatic head cancer.

Only 20% of patients with pancreatic cancer can undergo curative resection. Therefore, palliative treatment of pancreatic cancer assumes the utmost clinical importance. The aim of the palliative treatment of pancreatic head carcinoma is to relieve the jaundice and/or duodenal obstruction. Endoscopic or transparietal decompression of the obstructed bile duct can be accomplished in most cases, but the durability of these techniques is not as great as that of a surgically created bypass. On the other hand, hepaticojejunostomy carries higher morbidity and mortality rates than the former nonsurgical methods. In order to promote long lasting palliation with low morbidity and mortality rates, minimally invasive techniques of biliary and gastric bypass have been described. However, laparoscopic Roux-en-Y hepaticojejunostomy seems to be a complex surgical procedure. With an aim to simplify the construction of a laparoscopic hepaticojejunostomy, the authors suggest an alternative technique.

Female↗
PubMed2000

[Interest of free flaps for cranial base reconstruction].

We describe our experience in treating 7 patients who underwent skull base reconstruction with free flap (6 latissimus dorsi, 1 rectus abdominis) between October 1996 and November 1998. Four patients underwent temporal bone resection with auricular resection, 2 patients underwent anterior and middle cranial fossa resection, 1 patient underwent frontotemporal resection. There have been no failures of the free flaps and one cerebrospinal fluid leak. We advocate free flap reconstruction after temporal bone resection with auricular resection, and after anterior or middle cranial fossa resection when local flap options are not available or with complex dead space.

Adult↗
PubMed2000

[Hearing preservation in vestibular schwannoma surgery: indications, techniques and results in the literature since 1990].

Many authors have recently reported hearing preservation for approximately two-thirds of acoustic neuroma patients. The results have driven them to recommend early surgery for all patients whose hearing might be saved. Inversely, other authors advocate that MRI-screening may be beneficial in some patients and suggest surgery only in case of tumor growth or progressive hearing loss. In order to facilitate therapeutic decision making, we reviewed the techniques and results in the main papers dealing with hearing preservation in the course of acoustic neuroma surgery published since 1990. This analysis showed that the average percentage of useful hearing preservation is about 31%. It is however difficult to compare the different series due to the different methodologies used. This emphasizes the need for standardization of hearing selection and reporting criteria to a) identify factors predictive of success (tumor characteristics, preoperative hearing, monitoring, surgical pathways), and b) elaborate well accepted decisional guidelines (early surgery or MRI screening), notably for small and non-symptomatic tumors which show increasing prevalence.

Audiometry↗
PubMed1999

The fluorescence emission of the apo-glucose oxidase from Aspergillus niger as probe to estimate glucose concentrations.

We developed a new method of glucose sensing using an inactive form of glucose oxidase from Aspergillus niger. Glucose oxidase was rendered inactive by removal of the FAD cofactor. The resulting apo-glucose oxidase still binds glucose as observed from a decrease in its intrinsic tryptophan fluorescence. 8-Anilino-1-naphthalenesulfonic acid (ANS) was found to bind spontaneously to apo-glucose oxidase as seen from an enhancement of the ANS fluorescence. The steady state intensity of the bound ANS decreased 25% upon binding of glucose, and the mean lifetime of the bound ANS decreased about 40%. These spectral changes occurred with a midpoint from 10 to 20 mM glucose, which is comparable to the K(D) of holo-glucose oxidase. These results suggest that apo-glucose oxidase can be used as a reversible nonconsuming sensor for glucose.

Anilino Naphthalenesulfonates↗
PubMed1999

Synthesis and spectral characterization of a long-lifetime osmium (II) metal-ligand complex: a conjugatable red dye for applications in biophysics.

There is a need for luminescent probes, which display both long excitation and emission wavelengths and long decay times. We synthesized and characterized an osmium metal-ligand complex which displays a mean decay time of over 100 ns when bound to proteins. [Os(1,10-phenanthroline)2(5-amino-1,10-phenanthroline)[(PF6)2 can be excited at wavelengths up to 650 nm, and displays an emission maximum near 700 nm. The probe displays a modest but useful maximum fundamental anisotropy near 0.1 for 488-nm excitation, and thus convenient when using an argon ion laser. [Os(phen)2(aphen)](PF6)2 is readily activated to the isothiocyanate for coupling to proteins. When covalently linked to bovine serum albumin the intensity decay is moderately heterogeneous with a mean decay time of 145 ns. The anisotropy decay of the labeled protein displays a correlation time near 40 ns. This relatively long lifetime luminophores can be useful as a biophysical probe or in clinical applications such as fluorescence polarization immunoassays.

Biophysics↗
PubMed1999

Sensing of carbon dioxide by a decrease in photoinduced electron transfer quenching.

We described a new approach to sensing of carbon dioxide based on photoinduced electron transfer (PET) quenching. Fluorophores like naphthalene and anthracene are known to be quenched by unprotonated amines by the PET mechanism. We examined the fluorescence spectral properties of two amine-containing fluorophores, 1-naphthylmetylamine (NMA) and 9-ethanolaminomethylanthracene (EAA). When dissolved in an organic solvent, both fluorophores displayed increased intensity when equilibrated with gaseous carbon dioxide. In the case of NMA, we found that the mean lifetime increased with increasing partial pressures of CO(2). The intensity and lifetime changes of NMA are completely reversible when CO(2) is removed by purging with argon. Our results are consistent with decreased quenching by the covalently linked amino groups when CO(2) is dissolved in the solution. At present, we are not certain whether the increased intensity is due to protonation of the amino groups or to carbamate formation. In either event, these results suggest that CO(2) can be detected directly using amine-containing fluorophores without the use of bicarbonate and a pH-sensitive fluorophore.

1-Naphthylamine↗
PubMed1999

Transnasal endoscopic repair of congenital defects of the skull base in children.

OBJECTIVE: To examine imaging findings and methods of endoscopic treatment of congenital skull base defects in children. DESIGN: Retrospective study and case series. SETTING: Academic tertiary care center. PATIENTS: Four patients (aged 12 and 14 months and 8 and 13 years) were included from 1995 to 1997. Three presented with a nasal glioma, which was recurrent in 1 case. The fourth patient presented with bacterial meningitis due to a spontaneous cerebrospinal fluid leak. Computed tomography and magnetic resonance imaging were used to locate the defect of the skull base. INTERVENTION: Transnasal endoscopic resection of the glioma or the meningocele, with immediate repair of the skull base defects using free mucosal flaps and/or pediculized mucosal flaps and/or conchal cartilage together with fibrin glue and nasal packing during a 3-week period. RESULTS: None of the 4 patients has experienced recurrent cerebrospinal fluid leaks or postoperative meningitis. CONCLUSIONS: The transnasal endoscopic repair of congenital meningoceles is a reliable technique in select pediatric patients. Computed tomography and magnetic resonance imaging provide information that can be used to help the surgical procedure.

Adolescent↗
PubMed1999

Nasal haemangiopericytoma: report of two cases with literature review.

Haemangiopericytoma (HPC) is a rare vascular tumour produced by proliferation of pericytes. One hundred and thirty-three cases of HPC have been reported in the nose and the paranasal sinuses. We present two more cases. Wide surgical excision via lateral rhinotomy, midfacial degloving, or endonasal removal is the treatment of choice. Radiotherapy has been used post-operatively in cases of incomplete removal. Life-long follow-up is required to evaluate local recurrence and late metastases.

Aged↗
PubMed1999

In vitro evaluation of the haemopoietic defect of CD34+ cells from patients with acute myeloid leukaemia in first remission.

Haemopoietic cells from patients with acute myeloid leukaemia (AML) in first complete remission (CR1) show in vitro a haemopoietic defect and a decreased expansion potential. To better characterize this haemopoietic defect, CR1 AML and normal CD34+ cells were analysed for immunophenotype, viability, cell cycle and progenitor content before and during expansion culture in stroma-conditioned medium supplemented with cytokines. The production of haemopoiesis inhibitor by patient cells and the influence of high concentrations of stem cell factor (SCF) and Flt3-ligand (FL) on cell survival and ex vivo expansion potential were also studied. Before expansion, patient CD34+ cells showed viability and cell-cycle phase distribution similar to normal but lower percentages of CD34+DR- or CD34+CD38- cells and lower progenitor content. After 48 h of culture +/-30% of patient cells had died regardless of the cytokine combination used, whereas only 15% of normal cells died. After 7 d of culture, viability and cell cycle analyses showed comparable data for normal and patient samples. Co-culture of patient and normal cells did not show any evidence for haemopoiesis inhibitor production by patient cells. Even at high cytokine concentrations, a low progenitor expansion and a decrease in CD34+ cell numbers was observed for patient samples in contrast to normal samples. In conclusion, CR1 AML CD34+ cells showed excessive early cell mortality. No evidence for cell-cycle arrest or haemopoiesis inhibitor production was shown. SCF and FL used at high concentrations did not correct the patient cell expansion defect.

Acute Disease↗
PubMed1999

Long-term follow-up of juvenile nasopharyngeal angiofibromas: analysis of recurrences.

OBJECTIVES: Juvenile nasopharyngeal angiofibroma often recurs if the tumor is large. This report is a long-term follow-up of these cases. It establishes the prognostic values of tumor extensions, analyzes the anatomic factors involved in recurrences, describes the spontaneous evolution of remnants based on a radiographic follow-up, and evaluates the pertinence of complex combined surgical approaches for invasive tumors and the value of complementary endoscopy. STUDY DESIGN: Retrospective review of 44 cases treated between 1985 and 1996. METHODS: Statistical analysis of the correlation between recurrence and tumor extension as evaluated by systematic analysis of 18 putative tumor extensions on preoperative computed tomography scans. RESULTS: Invasion of the skull base affected two-thirds of the patients, and the rate of recurrence was 27.5%. Extensions to the infratemporal fossa, sphenoid sinus, base of pterygoids and clivus, the cavernous sinus (medial), foramen lacerum, and anterior fossa were correlated with more frequent recurrence. Long-term radiographic follow-up revealed putative residual disease in nine asymptomatic patients: these remnants gradually involuted. CONCLUSIONS: The data in the current study emphasize the prognostic value of skull base invasion and the difficulty of complete resection of extended lesions. Tumor remnants detected in symptom-free patients should be kept under surveillance by repeated computed tomography scan, since involution may occur. Recurrent symptoms may be treated by radiotherapy (30 Gy) rather than by extended combined procedures. Endoscopic surgery should be combined with surgery for better control of skull base extensions.

Adolescent↗
PubMed1999

Oxygen modulates Na+ absorption in middle ear epithelium.

The physiology of the middle ear is primarily concerned with keeping the cavities air filled and fluid free to allow transmission of the sound vibrations from the eardrum to the inner ear. Middle ear epithelial cells are thought to play a key role in this process, since they actively transport Na+ and water. The PO2 of the middle ear cavities varies from 44 to 54 mmHg in healthy human ears but may be lower in the course of secretory otitis media. The effect of chronic hypoxia on ion transport was investigated on a middle ear cell line using the short-circuit current technique. Chronic hypoxia reversibly decreased the rate of Na+ absorption across the MESV cell line. Although a decrease in cellular ATP content was observed, the decrease of Na+ absorption seemed related to a primary modulation of apical Na+ entry. As revealed by RNase protection assay, the decrease in the rate of apical Na+ entry strictly paralleled the decrease in the expression of transcripts encoding the alpha-subunit of the epithelial Na+ channel. This effect of oxygen on Na+ absorption might account for 1) the presence of fluid in the middle ear in the course of secretory otitis media and 2) the beneficial effect of the ventilation tube in treating otitis media that allows the PO2 to rise and restores the fluid clearance.

Absorption↗
PubMed1999

Transnasal endoscopic removal of an orbital cavernoma.

The approach to posterior and medial orbital tumors is still a challenge, since poor functional results are frequent. We report a case of cavernoma successfully removed by a modified transnasal endoscopic procedure. The patient, a 56-year-old woman, complained of a decrease in vision of the left eye. Magnetic resonance imaging evidenced a lesion in the posterior part of the orbital cavity, inferior to the optic nerve, extending to the sphenoidal cleft. The lesion was isodense on T1-weighted images and showed contrast enhancement. Because of the medial location of the tumor, the patient was referred to the otolaryngology department by the neurosurgeons, and a transnasal endoscopic approach was chosen. A large exposure of the operative field was obtained, and a cavernoma was removed. Rapid relief of the symptoms was obtained. In view of this good result, we advocate the transnasal endoscopic approach in cases of inferomedial and posterior intraconal lesions as an alternative and addition to the standard techniques of orbital surgery.

Endoscopy↗
PubMed1999

[Meno-metrorrhagia].

Menometrorrhagia is frequent. It consists in menorrhagia (excessive menstrual flow and duration) and metrorrhagia (irregular, excessive flow and duration). Three different types of aetiology occur: general extra-gynaecological causes, endocrine causes and organic causes. This last group is made of myomas, polyps, endometrial hyperplasia, adenomyosis and uterine cancers. Dysfunctional uterine bleedings do not find their cause in one of these three main causes. The diagnosis is based on three types of complementary investigations: endo-uterine cytological and histological samplings, medical imaging of which endovaginal echography is the most accurate, and diagnostic hysteroscopy. This triad allows to reach a very precise diagnosis in order to exclude a malignant lesion. Thanks to this precise diagnosis, the therapeutic decision is made according to the nature of the lesion to be treated, the desire to retain fertility, and age. Medical and surgical treatments are possible. In most cases of general extra-gynaecological and endocrine causes, medical treatment is efficient and etiological. When organic uterine lesions are present, several medical treatments are efficient by suppressing the cause of bleeding or by symptomatic action. Main medical treatments are: anti-fibrinolytic agents, nonsteroidal anti-inflammatory drugs, progestin, oral contraceptive pills, GnRH agonists and danazol. The surgical treatment consists in endoscopic techniques (operative hysteroscopy and laparoscopy) and hysterectomy performed by vaginal route with or without laparoscopic preparation, by laparoscopic approach only or by classical laparotomy. Currently, the classical D & C has become essentially a diagnostic method. Surgical treatment is necessary after failure of a medical treatment or in the presence of a lesion not directly accessible to medical therapy. The efficacy of conservative endoscopic techniques depends on the respect of the indications of these techniques. These allow to reduce the number of hysterectomies for benign lesions by up to 50%.

Diagnosis, Differential↗
PubMed1999

Primary intrahepatic lithiasis: report of a case treated by laparoscopic bilioenteric anastomosis.

Recent advances in videolaparoscopic surgery have made this method the treatment of choice for many biliary diseases. However, it has not been used in certain cases, such as primary intrahepatic lithiasis. The authors report a case of a 62-year-old woman with a history of several episodes of cholangitis. Investigation revealed dilated intra- and extrahepatic bile ducts with intrahepatic stones. The patient underwent laparoscopy, and intraoperative cholangiography disclosed an enlarged common duct with absence of stones and the presence of multiple calculi in the intrahepatic biliary tree. A choledochotomy followed by choledochoscopy was performed, which revealed several intrahepatic pigmented stones that were completely retrieved, followed by a laterolateral choledochoduodenostomy to decompress the biliary tree and to allow the migration of residual or recurrent stones. The patient had an uneventful recovery and was discharged on the fourth postoperative day. After 15 months of follow-up the patient is asymptomatic with normal results of liver function tests. Late postoperative upper digestive endoscopy showed a patent choledochoduodenostomy.

Bile Ducts, Intrahepatic↗
PubMed1998

Molecular distance measurements reveal an (alpha beta)2 dimeric structure of Na+/K+-ATPase. High affinity ATP binding site and K+-activated phosphatase reside on different alpha-subunits.

ATP hydrolysis by Na+/K+-ATPase proceeds via the interaction of simultaneously existing and cooperating high (E1ATP) and low (E2ATP) substrate binding sites. It is unclear whether both ATP sites reside on the same or on different catalytic alpha-subunits. To answer this question, we looked for a fluorescent label for the E2ATP site that would be suitable for distance measurements by Förster energy transfer after affinity labeling of the E1ATP site by fluorescein 5'-isothiocyanate (FITC). Erythrosin 5'-isothiocyanate (ErITC) inactivated, in an E1ATP site-blocked enzyme (by FITC), the residual activity of the E2ATP site, namely K+-activated p-nitrophenylphosphatase in a concentration-dependent way that was ATP-protectable. The molar ratios of FITC/alpha-subunit of 0.6 and of ErITC/alpha-subunit of 0.48 indicate 2 ATP sites per (alpha beta)2 diprotomer. Measurements of Förster energy transfer between the FITC-labeled E1ATP and the ErITC-labeled or Co(NH3)4ATP-inactivated E2ATP sites gave a distance of 6.45 +/- 0.64 nm. This distance excludes 2 ATP sites per alpha-subunit since the diameter of alpha is 4-5 nm. Förster energy transfer between cardiac glycoside binding sites labeled with anthroylouabain and fluoresceinylethylenediamino ouabain gave a distance of 4.9 +/- 0.5 nm. Hence all data are consistent with the hypothesis that Na+/K+-ATPase in cellular membranes is an (alpha beta)2 diprotomer and works as a functional dimer (Thoenges, D., and Schoner, W. (1997) J. Biol. Chem. 272, 16315-16321).

Adenosine Triphosphate↗