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Biomedical subjects

B Peter

Publications and source records attributed to B Peter.

At least 37 records · Page 2Linked to original sources
PubMed1997

[Inverted papilloma of the nose and paranasal sinuses].

BACKGROUND: Inverted papilloma is a rare benign tumor of the nose and the paranasal sinuses. There is a controversial discussion concerning the operative approach. The epidemiology, postoperative results, and recurrence rates of endonasally and extranasally operated patients are analysed. PATIENTS: Between 1984 and 1995, 25 patients with inverted papilloma were operated upon at the ENT Department St. Gallen, 18 patients by an endonasal microscopic approach, two by midfacial degloving and five through a lateral rhinotomy. RESULTS: After a minimal follow-up of 12 months (mean follow-up 52 months), a recurrence rate of 29% for the external approach and 31% for the endonasal approach was observed. CONCLUSIONS: In most cases it is possible to achieve a good result through an endonasal approach. External approaches are recommended in T4-tumors or carcinomas. A longtime follow-up is recommended for each case.

Adult↗
PubMed1996

Simulation of titration curves indicated with two indicator electrodes (biamperometry).

A rigorous method to simulate titration curves with indication using two indicator electrodes (biamperometry) is presented. Computer simulations can be carried out for reversible as well as for irreversible systems. The different parameters like the area of the individual electrodes, applied potential difference, heterogeneous rate constant, and the kinetic parameter alpha were varied and investigated as to their influence upon the shape of the titration curves. The theoretically derived effects match with the effects obtained by experiment. Considering the effects described here, it is possible to tailor the shape of the titration curve by the experimental conditions for specific applications in order to get an optimum shape at the end point of the titration.

Journal Article↗
PubMed1996

Bivoltametric titrations using electrodes with innovative geometry.

Electrodes with different surface areas were investigated for the determination of reversible, quasireversible, irreversible or electroinactive substrates. Two kinds of electrodes were constructed, a helical electrode with a given asymmetry and a platinum array electrode with a variable area. These electrodes were applied for the cerimetry of ammonium iron(II) sulfate and for the bromatometry of various organic substances. The theoretically derived effects on the shape of the voltametric titration curve are verified experimentally. It is possible to sharpen one side of the peak and to broaden the other side, depending on the system and the side of the peak one is interested in. It is possible to improve the bivoltametric determination of hydroquinone, benzocaine and sulfaguanidine by bromatometry by the directed employment of electrodes of different areas. For the bromatometric determination of electrochemically irreversible substrates the use of the electrode geometries proposed is a way to obtain a sharp bend and a steep decrease of titration curves with low values of the constant current which is a basic requirement for the accuracy.

Journal Article↗
PubMed1996

[AIDS-related eosinophilic folliculitis. Efficacy of high dose topical corticotherapy].

INTRODUCTION: A chronic pruriginous eruption of eosinophil-rich follicular papules and pustules is observed in AIDS patients. The pathogenesis of this disease, termed eosinophil folliculitis, is poorly understood and treatment is debated. CASE REPORT: A 30-year-old woman with AIDS developed highly pruriginous lesions of 5 month duration localized on the face, the trunk and upper limbs. There were papulo-pustules and excoriated papules. The elementary lesion was a follicular pustula. The eosinophil count was normal. The pathology examination revealed a rich eosinophil infiltration around the hair follicles and sebaceous glands as well as follicular spongiosis. Search for demodex, pityrosporons and a large number of infectious agents was negative. Oral minocyclin was uneffective. Local high-dose corticosteroids produced a remarkable effect and led to complete remission in 9 months. DISCUSSION: Most cases of eosinophil folliculitis associated with AIDS have been reported in men, but rarely in Europe. The remarkable efficacy of the local corticosteroid in this case was exceptional. This condition could result from inappropriate inflammatory reaction in AIDS induced by various factors including demodex and pityrosporon. Several therapeutic approaches have been proposed to eradicate the triggering factors and others to modify the immune response. The exceptional response to the short local treatment with corticosteroids would suggest that this approach could be proposed as first intention treatment in eosinophil folliculitis associated with AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Analysis of CpG dinucleotide frequency in relationship to translational reading frame suggests a class of genes in which mutation of this dinucleotide is asymmetric with respect to DNA strand.

Results are described from application of a computer program that compares the expected and actual incidence of CpG dinucleotides in relation to the codon reading frame of genes, assuming a conserved amino acid sequence and normalizing for the third-position incidences of C and G in the remainder of the sequence. Sequences encoding certain proteins showed a pronounced bias in favour of CpG in the (3,1) compared with the (2,3) codon position; whereas sequences encoding related proteins expressed to a similar extent or in the same tissue did not. We propose that the cases exhibiting this bias reflect a difference between the two strands of the DNA duplex in their susceptibility to loss of CpG dinucleotides by mutation. Although in vertebrates this loss of CpG dinucleotides from the sense strand might reflect strand-asymmetry in deamination of 5-methylcytosine residues, the fact that a similar CpG codon bias is found in some invertebrates indicates that other factor(s) must also be involved.

Actins↗
PubMed1995

[Stapes revisions: clinical findings and results].

By correlating the intraoperative findings and the postoperative hearing gain it was attempted to determine the recommendable intraoperative management in stapesrevisions in order to obtain the best postoperative hearing. In a retrospective study the findings of 39 stapes revision operations were analyzed. In most of the cases hearing one year postoperatively was compared with preoperative hearing. The prognosis for good hearing was best following replacement of the prosthesis where the prosthesis was too short or dislocated, or in the presence of a loosened wire. Where treatment only entailed retightening the loosened wire at the long process of the incus, postoperative hearing did not improve. Patients with an obliterative otosclerosis or an additional fixed incus had a less favorable prognosis. Overall a postoperative air bone gap of 10 dB or below was obtained in 44% of the patients and a postoperative air bone gap of 20 dB or below in 77% of the patients. Twenty-one percent of the patients remained unchanged, and in one patient postoperative deterioration of the hearing was detected.

Adult↗
PubMed1995

Degranulation of rat salivary glands following treatment with receptor-selective agonists.

1. The aim of this study was to find a drug that induces an almost complete degranulation of secretory cells in rat parotid and submandibular glands. 2. Phenylephrine (alpha-adrenergic), isoproterenol (beta-adrenergic) and mecholine (muscarinic cholinergic) were tested. Time and degree of maximal depletion of acinar and granular convoluted tubule cells were determined morphologically. 3. Following phenylephrine-injection (5 mg/kg or 10.2 mg/kg, i.p.), no effect on the acinar granulation level was observed in either of the glands, while about 50-60% granular convoluted tubules were degranulated for at least 120-180 min post-injection. 4. With isoproterenol (5, 10, 40, 70 or 100 mg/kg, i.p.), degranulation of 100% of the acinar cells in the parotid and 80% of the acinar cells in the submandibular gland was observed 90 min post-injection. Granular convoluted tubule cells did not respond to this beta-adrenergic drug. 5. Mecholine (3.75 or 7.5 mg/kg, i.p.) induced mainly degranulation of granular convoluted tubule cells (about 50% after 120 min). Numbers of granulated acinar cells decreased only slightly in both glands (about 10%, 90-120 min). 6. From this study it appears that with a relatively low dosage (5 mg/kg, i.p.) of isoproterenol, a high level of degranulation can be induced in acinar cells of rat parotid and submandibular glands without toxic side effects. Concerning granular convoluted tubules, only moderate degranulation was observed with phenylephrine and mecholine, respectively.

Adrenergic alpha-Agonists↗
PubMed1995

[Magnetism and immorality--or the rapid demise of magnetism in Berlin around 1819-1820].

In the years 1821 and 1822 two books offered contradictory accounts of a scandal in Berlin involving sexual abuse in connection with magnetism. Historical research has determined that the accused was the famous physician and magnetizer Karl Christian Wolfart. If, however, we look more closely at the general context, it appears that this was not just a case of abuse of the therapeutic relationship. Rather, it is suggested that a specific combination of therapeutic ignorance and particular psycho-social influences contributed almost inevitably to the abuse of patients--sexually or otherwise.

Berlin↗
PubMed1995

The role of secretory granules in radiation-induced dysfunction of rat salivary glands.

To investigate the possible role of secretory granules in radiation-induced salivary gland dysfunction, rats were pretreated with isoproterenol (5 mg/kg intraperitoneally) to degranulate salivary gland acini. At maximal depletion, salivary glands were locally irradiated with a single dose of 15 Gy of X rays. Parotid and submandibular/sublingual saliva samples were collected before and 1-10 days after irradiation. The lag phase, flow rate, concentrations of potassium and sodium, and amylase secretion were determined. Sham-treated, isoproterenol-treated and irradiated animals provided reference data. In the parotid gland, but not in the submandibular gland, protection against radiation-induced changes in flow rate and composition of saliva occurred after pretreatment with isoproterenol. Combining morphological data from a previous study with data from the current study, it is suggested that improvement of parotid gland function is attributed predominantly to a proliferative stimulus on acinar cells by isoproterenol and not to its degranulation effect. After pretreatment with isoproterenol, an earlier expression of radiation-induced acinar cell damage leading to death was observed, followed by a faster tissue recovery. Thus the proliferative stimulus on acinar cells may accelerate the unmasking of latent lethal damage, resulting in the earlier replacement of dead cells by new, functionally intact cells.

Animals↗
PubMed1994

Radiation-induced cell proliferation in the parotid and submandibular glands of the rat.

Repopulation of tissues with cells at damaged sites is an important feature in the recovery of radiation-induced tissue injury. To obtain insight into the regenerative process in salivary gland tissue, proliferative activity was measured as a function of time in the different epithelial cell compartments of rat parotid and submandibular glands after local X irradiation with a single dose of 15 Gy. Bromodeoxyuridine-labeling indices were determined before and 10 h and 1, 3, 6, 10, 15, 20 and 30 days after irradiation. In both glands, X irradiation caused cell death and cell cycle delay manifested during the first day. Three days after irradiation, cell proliferation started in the intercalated duct. Six days after irradiation, proliferation was also observed in acinar and granular convoluted tubule cells. The striated ducts showed proliferative activity starting at day 6 (parotid) and day 10 (submandibular), respectively. The results of this study suggest that after 15 Gy of X rays repopulation takes place in all cell compartments. From the present study it cannot deduce if these cells are originating solely from progenitor cells residing in the intercalated duct or if cells of the other compartments are also stimulated. Proliferative activity was found to be higher in the intercalated duct compartment of the parotid gland than of the submandibular gland, which may be related to the suggested greater radiosensitivity and thus a greater demand for cell replenishment in the parotid gland.

Animals↗
PubMed1994

The role of secretory granules in the radiosensitivity of rat salivary gland acini--a morphological study.

The aim of this study was to investigate the radiosensitivity of salivary gland tissue pretreated with isoproterenol to establish a status of depletion of secretory granules in acinar cells at the time of irradiation. Nuclear aberrations and cell lysis were taken as parameters for cell death. Local X irradiation with a single dose of 15 Gy induced comparable early morphological changes in the rat parotid and submandibular glands. During the first day after irradiation, the most obvious changes were degranulation of serous cells and induction of nuclear aberrations in both the secretory (serous as well as mucous) and intercalated duct compartment. Subsequently, progressive lysis occurred in secretory units but not in intercalated and striated ducts. Recovery of tissue integrity was observed from day 6. Early radiation-induced cell death was not reduced by isoproterenol-induced degranulation of acinar cells before irradiation. Subsequent recovery from radiation damage seemed to occur earlier in parotid glands but not in submandibular glands pretreated with isoproterenol. From the present study it is concluded that the radiosensitivity of serous salivary gland acini is not dependent on the presence of secretory granules at the time of irradiation. There was some evidence for a faster recovery from radiation damage observed after pretreatment with isoproterenol which may be the result of drug-induced stimulation of cell proliferation.

Animals↗
PubMed1993

Urinary retention in the elderly: a study of 100 hospitalized patients.

OBJECTIVE: To estimate the prevalence of incomplete bladder emptying by the elderly and to determine its significance and its relationship to overflow incontinence. DESIGN: Survey comparing groups with and without incomplete bladder emptying. SETTING: A geriatric hospital ward. PATIENTS: One hundred patients who were consecutively admitted, with an average age of 82.6 years. MEASUREMENTS: A physical examination, perineal examination, micturition assessment, and evaluation of the post-voiding residual urine volume (PRUV) by ultrasonography at day 1 and day 8 following admission. One-channel cystometry and urine cultures were also done. Between-group comparison was performed between groups R (ie, PRUV greater than 50 mL) and C (ie, PRUV less than 50 mL). MAIN RESULTS: The prevalence of PRUV greater than 50 mL was 34%. Group R patients presented with greater dependency; death was the final outcome of hospitalization in 36% of these cases (vs only 9% in group C). A high PRUV was not correlated with urinary tract infection or renal failure, but there was a strong, almost significant trend toward incontinence being more prevalent in R (57%) than in C (38%) (P = 0.06). Group R presented a hypotonic bladder in 45% of cases, evidenced by cystometry, versus 6% in group C. CONCLUSIONS: In cases with a high PRUV, the utmost caution is necessary both in the diagnosis of overflow incontinence and in establishing a therapeutic approach. Incomplete bladder emptying is associated with a poor prognosis.

Activities of Daily Living↗
PubMed1992

Role of lipid peroxidation and DNA damage in paraquat toxicity and the interaction of paraquat with ionizing radiation.

Since the introduction of paraquat (PQ) as a herbicide in 1963, there have been many speculations concerning the critical lesion in PQ toxicity. Damage to membrane lipids might be an initial event leading to PQ-induced cell killing. The ability of PQ to induce lipid peroxidation was tested in liver homogenates of the mouse. Lipid peroxidation was indeed induced by PQ and shown to be dose dependent, starting to be significant at 2.5 mM. Subsequently, a possible correlation between lipid peroxidation and PQ-induced cell death was investigated in mouse fibroblasts (LM) and Ehrlich ascites tumour (EAT) cells using a clonogenic assay. It was found that in order to be cytotoxic PQ needs enzymatic activation (incubation at 37 degrees). In both cell lines, PQ-induced cell killing appeared to be dose dependent, starting at a dose of 0.5 mM. Supplementation of LM cells with the antioxidant vitamin E had no effect on PQ-induced cell killing and modification of the membranes of LM cells by incorporation of the polyunsaturated fatty acid 20:4 (arachidonic acid) did not sensitize the cells to PQ toxicity. PQ had no effect on the glutathione (GSH) level in EAT cells and complete GSH depletion by DL-buthionine-(SR)-sulfoximine could not sensitize the cells to PQ toxicity. In LM cells PQ-induced cell killing was enhanced after complete GSH depletion by DEM. This sensitization might, however, be attributed to the binding of DEM to proteins. From these results it seems unlikely that lipid peroxidation is the primary cause for PQ-induced cell killing. Another critical target in PQ toxicity is DNA. This possibility was investigated in EAT cells. PQ was found to induce DNA damage (detected by the alkaline unwinding assay) in the same dose range that caused cell death. A good correlation was obtained for cell killing after PQ treatment and DNA damage measured 2 hr after 37 degrees post-incubation. A proposed possible interaction between PQ and X-rays was also investigated. In EAT cells, X-ray-induced cell death was significantly enhanced by pre-incubation with PQ at doses of 0.5 mM and above. At the level of 10% survival an enhancement factor of 1.6 could be observed by treatment with 1 mM PQ when cell killing by PQ is not taken into account. Induction as well as processing of radiation-induced DNA damage seems to be unaffected by pre-incubation with PQ. The mechanism of radiosensitization by PQ is yet unclear.

Animals↗
PubMed1989

Combined subtotal pancreatectomy with selective streptozotocin infusion--a model for the induction of insulin deficiency in dogs.

Standardized models of type I diabetes-like insulin deficiency in larger laboratory animals hardly exist. It was therefore investigated whether stable long-term insulin deficiency in dogs can be induced by selective beta-cell destruction in a safe and reliable procedure without damage of other organs. In Beagle dogs, the diabetogenic response to systemic streptozotocin administration (38.5-28 mg/kg b.wt.) was tested. In addition, resection of corpus and cauda pancreatis in combination with selective streptozotocin perfusion (25 mg/kg b.wt.) of the remaining pancreas tissue was evaluated. Whereas systemic streptozotocin administration failed to destroy insulin secretion, but led to a variety of intoxication symptoms even in comparatively low doses (28 mg/kg b.wt.), the latter procedure resulted in a complete and persistent insulin depletion (basal serum immunoreactive insulin less than or equal to 3 microU/ml, no stimulated response) without toxic organ damage or other serious side effects. The dogs developed type I-like diabetes, which required continuous exogenous insulin substitution. From these results, subtotal pancreatectomy with selective streptozotocin perfusion of the remaining pancreas is proposed as a safe model of insulin deficiency in dogs, which should be further evaluated in experimental diabetology.

Animals↗
PubMed1988

Mouse cytoskeletal gamma-actin: analysis and implications of the structure of cloned cDNA and processed pseudogenes.

The nucleotide sequence corresponding to almost the whole of a mouse gamma-cytoskeletal actin mRNA was determined from overlapping cloned DNA copies derived from brain mRNA. Several gamma-actin processed pseudogenes were isolated from a library of cloned DBA mouse genomic DNA, and the nucleotide sequences of these were determined and compared with that of the cDNA. This showed that two of these pseudogenes had arisen from a gene duplication or amplification event, and indicated that they had subsequently undergone partial correction against one another. The relative ages of the pseudogenes were estimated on the basis of their percentage divergence from the cDNA sequence and these were compared with an estimation based on the number of presumed silent mutations in the cDNA since each pseudogene had arisen. Consistent results were obtained, except in the case of one pseudogene which also showed an anomalous regional distribution of differences from the cDNA sequence. One way of accounting for the features of this anomalous pseudogene is by postulating that it is derived from a second functional gene for gamma-actin, different from that represented by the cDNA described here.

Actins↗
PubMed1988

[1-year prognosis of syncope and brief loss of consciousness in patients over 65. A multicenter study of 188 cases].

The one-year outcome of syncope and transient loss of consciousness was studied prospectively in 188 patients aged over 65 admitted to internal medicine departments. Thirty-seven patients (19.6 p. 100) died. This mortality rate at one year was 2.34 times higher than that of a non-hospitalized french population of the same age group (standardized mortality ratio, SMR = 2.34, P less than 0.001). The frequency of sudden death (7 cases) was much higher than that observed in the reference population (0.05 expected deaths, P less than 0.0001). Overmortality was clearly apparent in groups with an initial diagnosis of heart disease (SMR = 2.36, P less than 0.01) or neurological disease (SMR = 4.25, P less than 0.001). The relapse rate was 28 p. 100 globally and up to 43 p. 100 in cardiac patients. In the group with iatrogenic symptoms treatment was appropriately corrected in 86 p. 100 of the patients, and none of these relapsed. One year after the initial episode 11 p. 100 of the surviving patients had been institutionalized.

Aged↗
PubMed1985

The ABO and Rhesus groups in the north of Nigeria.

ABO and Rhesus blood group data were analysed from 43187 blood donors belonging to 34 ethnic groups, predominantly from northern Nigeria. This is the largest series to be reported on from the whole of West Africa. Group O was found in 46.6% of all those examined, but the numbers varied from 33.13% to 64.35% in different ethnic groups. Group A was found in 23.05% and Group B in 25.95%, but again there was much variation in the distribution of the blood groups in different ethnic groups. There was an overall frequency of 3.64% of Rhesus negatives, ranging from 1.4% to 8.72% in different ethnic groups. The results provide basic but useful information concerning many ethnic groups whose blood groups have not previously been reported.

ABO Blood-Group System↗