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Biomedical subjects

A Stanek

Publications and source records attributed to A Stanek.

At least 37 records · Page 2Linked to original sources
PubMed1998

Role of sialoglycan structures for the function of the epidermal growth factor receptor and the in vitro proliferation of head and neck cancer.

Squamous cell carcinomas of the head and neck have been found to show a high expression of the receptor for epidermal growth factor (EGF). This overexpression of the receptor has been associated with malignant transformation of cells, although there is still debate as to what extent this receptor takes part in the proliferation of malignant cells and which function it fulfills. The factors which determine receptor-ligand interaction are also not clearly defined. That the extracellular domain of the EGF receptor carries carbohydrate or sialoglycan structures might be important for function of the receptor. Since tumor specific enzymes can possibly alter such structures, it was the aim of our study to investigate the role of these structures on the EGF receptor during the proliferation of head and neck carcinomas. We used the human laryngeal squamous carcinoma cell line HLaC 79 and altered, for the first time, specific glycan structures with sialidase alpha-2,3 and alpha-2,6, causing desialylation. Changes were also produced by endo-beta-galactosidase and sialyltransferase. Findings were monitored by labeling with bromo-deoxyuridine. To determine receptor affinity, 125I-labeled EGF was employed. Results showed that both cell proliferation and receptor affinity depended on the level of sialylation of the receptor carbohydrate side chains. Desialylation led to a statistically significant reduction of tumor cell proliferation to 65 +/- 33% (P < 0.01), while receptor affinity decreased to 70 +/- 26% (P < 0.01). The importance of EGF receptor for the proliferation of malignant cells seems to depend on the level of sialylation of glycan structures on receptor protein. A release of enzymes by tumor cells may then produce auto-control of tumor proliferation on its own.

Binding Sites↗
PubMed1998

Effects of normobaric oxygen on ciliary beat frequency of human respiratory epithelium.

Respiratory infection is a major cause of morbidity after general anaesthesia. Impairment of respiratory ciliary beat frequency (CBF) by different stress factors causes a decrease in mucus transport rate (MTR). We have tested the effect of different concentrations of oxygen on CBF of human respiratory epithelium in a prospective, randomized, in vitro study. Samples of superficial mucosa of the inferior nasal turbinates of 20 non-smoking healthy volunteers were harvested and exposed to three different oxygen environments (group I = 21% oxygen, group II = 60% oxygen and group III = 95% oxygen) for 2 h. In 50% of the samples, exposure time was prolonged. At 30, 60, 90, 120 and 240 min, light microscopic images of cilia activity were videotaped and CBF was later assessed in slow motion. Compared with baseline, group I showed no difference in CBF throughout the study. CBF was increased in group II from mean 9.7 (SD 0.4) to 11.2 (0.4) Hz (16%, P < 0.001) and in group III from 9.5 (0.6) to 12.1 (0.5) Hz (28%, P < 0.001) at 120 min. After 240 min of exposure to 95% oxygen, the CBF trend in group III was reduced to 11.8 (0.6) Hz but still remained above baseline. We conclude that oxygen appeared to have a dose- and time-dependent accelerating effect on CBF. Prolonged exposure to high oxygen concentrations reversed this trend. Direct oxygen toxicity ("oxygen stress") is a possible explanation for this effect. These changes may result in impaired MTR.

Cilia↗
PubMed1998

Laryngeal mask airway position and the risk of gastric insufflation.

UNLABELLED: A potential risk of the laryngeal mask airway (LMA) is an incomplete mask seal causing gastric insufflation or oropharyngeal air leakage. The objective of the present study was to assess the incidence of LMA malpositions by fiberoptic laryngoscopy, and to determine their influence on gastric insufflation and oropharyngeal air leakage. One hundred eight patients were studied after the induction of anesthesia, before any surgical manipulations. After clinically satisfactory LMA placement, tidal volumes were increased stepwise until air entered the stomach, airway pressure exceeded 40 cm H2O, or air leakage from the mask seal prevented further increases in tidal volume. LMA position in relation to the laryngeal entrance was verified using a flexible bronchoscope. The overall incidence of LMA malpositions was 40% (43 of 108). Gastric air insufflation occurred in 19% (21 of 108), and in 90% (19 of 21) of these patients, the LMA was malpositioned. Oropharyngeal air leakage occurred in 42%, and was independent of LMA position. We conclude that clinically unrecognized LMA malposition is a significant risk factor for gastric air insufflation. IMPLICATIONS: Routine placement of laryngeal mask airways does not require laryngoscopy. In our study, fiberoptic verification of mask position revealed suboptimal placement in 40% of cases. Such malpositioning considerably increased the risk of gastric air insufflation.

Adult↗
PubMed1998

[Laparoscopic treatment for parapubic hernia, complications after radical prostatectomy].

We present laparoscopic method of treatment of parapubic hernia that may occur after radical prostatectomy performed due to prostatic cancer. This kind of hernia is closely related to the weakening of the rectus muscle of abdomen insertions to the pubic bone that takes place during the operations using lower midline incision in order to reach organs in the small pelvis. Because of its localization it may be misdiagnosed as a commoner direct inquinal hernia. In this case the traditional anterior approach would not be curative. Using laparoscopy as it is suggested by authors will make the proper diagnosis much more easy and thus will enable effective treatment of the patient.

Diagnosis, Differential↗
PubMed1997

Subacute paraparesis induced by venous thrombosis of a spinal angiolipoma: a case report.

STUDY DESIGN: A case report of spinal extradural angiolipoma, a rare tumor that can cause spinal cord compression, is presented with a complete review of the literature related to this disorder. OBJECTIVES: To discuss venous thrombosis involving the angiolipoma in the development of subacute paraparesis. SUMMARY OF BACKGROUND DATA: This case shows that venous thrombosis of a spinal angiolipoma can precipitate the subacute onset of paraparesis. METHODS: Medical history, physical findings, and the results of imaging and histopathologic studies were analyzed to elucidate the pathogenesis of the patient's subacute onset of paraparesis. A bilateral T3-T7 laminectomy was performed, and although the tumor was extremely hemorrhagic, it was mobilized easily off the compressed dura to achieve resection. RESULTS: The postoperative course was uneventful. One month after her surgery, the patient's myelopathic symptoms had resolved, and the she was able to return to work. CONCLUSION: Because the prognosis after surgical management of these lesions is favorable, the diagnosis of thrombosis involving a spinal angiolipoma should be considered in the differential diagnosis of subacute spinal cord compression.

Acute Disease↗
PubMed1997

[The interaction between rocuronium and smoking. The effect of smoking on neuromuscular transmission after rocuronium].

UNLABELLED: Recent studies have shown different results concerning the effects of smoking on neuromuscular blocking agents. Some reports indicate that smokers need higher doses of vecuronium, but are more sensitive to atracurium. The aim of this study was to evaluate the effects of smoking on onset and recovery time after a single 0.6 mg/kg intubating dose of rocuronium an analog of vecuronium. METHODS: Following institutional approval and informed consent, 20 smokers (> 10 cigarettes/day) and 20 nonsmokers were included in the study. Following oxazepam premedication and induction with fentanyl and thiopental, single-twitch stimulation of the ulnar nerve was performed every 10 s. Following stabilisation of control responses, patients received rocuronium 0.6 mg/kg for intubation. Anaesthesia was maintained with enflurane < or = 0.8 vol.% (end-tidal) and 65% nitrous oxide in oxygen. Onset time and recovery to 25% and 75% of the twitch control values were recorded. RESULTS: Onset and recovery times were not different between smokers and nonsmokers. CONCLUSIONS: The results of the present study suggest that chronic nicotine exposure does not change onset time or duration of rocuronium neuromuscular blockade. A previous study found a greater need for vecuronium in smokers and discussed stimulation of the neuromuscular junction and enhanced biotransformation due to the enzyme-inducing properties of nicotine. The differences in our results could be partly due to a longer period of refraining from smoking in our patients, leading to very low nicotine blood concentrations without the proposed receptor-stimulating effect. Another cause for different behaviour of the two analogs could be different elimination pathways. Recent investigations suggest that rocuronium may not be eliminated principally by the liver. Therefore, enhanced nicotine-induced biotransformation, as suggested for vecuronium, would not occur with rocuronium.

Adult↗
PubMed1997

[Modification of proteins in the course of oxidative stress in acute experimental pancreatitis].

This study aimed to investigate the protein peroxidation process in cerulein induced acute pancreatitis. Eighteen rats were divided into three equal groups: group 1 acted as control rats had intraperitoneal injection of 0.9% NaCl, in group 2 and 3 rats had injection of cerulein 40 micrograms kg-1 for 3 or 6h of induction period respectively. Protein carbonyls which reflect peroxidative damage were found to be increased after 3h up to 2.53 +/- 0.49 comparing to 1.05 +/- 0.17 in control group and returned to control level 0.95 +/- 0.04 after 6h. These data suggest that during acute pancreatitis free radicals may play an essential role in protein damage. Decrease in protein carbonyls content after 6h suggests an elevated proteolysis of oxidatively damaged proteins.

Acute Disease↗
PubMed1996

[The effects of cimetidine on the pharmacodynamics of rocuronium].

UNLABELLED: Cimetidine is a commonly used H2-receptor antagonist that has been recommended for the prevention of acid aspiration syndrome and has been shown to potentiate vecuronium-induced neuromuscular block. The present study was designed to investigate the influence of a single IV dose of cimetidine on the neuromuscular effects of rocuronium, an analogue of vecuronium with a short onset time. METHODS: Twenty adults aged 18-65 years were included in the study with their informed consent and approval of the Ethics Committee. Following oxazepam premedication, 10 patients were randomly allocated to receive cimetidine 400 mg IV 30 min before anaesthesia. After fentanyl and thiopentone induction, single-twitch stimulation of the ulnar nerve was performed every 10 s. Following stabilisation of control responses, patients received rocuronium 0.6 mg/kg for intubation. Anaesthesia was maintained with enflurane < or = 0.8 vol.% (end-tidal) and 65% nitrous oxide. Onset time and recovery times to 25% and 75% of the twitch control values were recorded. RESULTS: Onset and recovery times did not differ between groups. CONCLUSIONS: The results of the present study demonstrate that cimetidine does not increase the duration of rocuronium neuromuscular blockade. Inhibition of the cytochrome P450 system or a direct effect at the neuromuscular junction have been suggested as the mechanisms of drug interaction associated with cimetidine. Impairment of hepatic microsomal drug metabolism results in a prolonged duration of action of vecuronium, which appears to be eliminated primarily via the liver. Data on the elimination pathway of rocuronium in humans are not available. The fact that cimetidine does not alter the recovery from rocuronium-induced neuromuscular block confirms a previous suggestion that rocuronium may not be eliminated principally by the liver. A direct effect of cimetidine on the neuromuscular junction could not be confirmed by this study. Therefore, cimetidine can be given as premedication without a risk of prolonged rocuronium block.

Adolescent↗
PubMed1996

[Intubation requirements after rocuronium and succinylcholine].

OBJECTIVE: Rocuronium is a new non-depolarising steroidal muscle relaxant with a short onset time. The present study was undertaken to compare intubating conditions as well as onset and clinical duration of a single dose of 0.6 mg/kg (2 x ED95) with a single dose of 1 mg/kg suxamethonium (3 x ED95). METHODS: After obtaining informed consent and approval of the Ethics Committee, 40 adult patients (ASA I-III) participated in this study. After premedication with oxazepam, anaesthesia was induced with fentanyl and propofol and maintained with propofol, N2O and supplements of fentanyl as needed. Muscular relaxation was assessed by EMG recording of adductor pollicis muscle after supramaximal single twitch stimulation of the ulnar nerve every 10 s. Patients were allocated randomly to receive either rocuronium 0.6 mg/kg or suxamethonium 1 mg/kg. The following parameters were measured: intubating conditions 60 s after injection, onset time and clinical duration of neuromuscular block, % block at intubation, heart rate, blood pressure and arterial oxygen saturation. RESULTS: (mean +/- SD). Intubating conditions after rocuronium and suxamethonium were found to be clinically acceptable (excellent or good) in 90% of patients, though there was only a partial blockade of the adductor pollicis muscle with rocuronium (71 +/- 23%) compared to suxamethonium (95 +/- 14%) (p < 0.05). The onset time and clinical duration of relaxation was shorter after suxamethonium (p < 0.05) and occurred at 0.8 +/- 0.2, 7 +/- 2.1 and 3.2 +/- 1.3, 29 +/- 11 min after suxamethonium and rocuronium respectively. CONCLUSION: At a dosage of 0.6 mg/kg, rocuronium has an onset time of about 3 min and a clinical duration of relaxation of nearly half an hour. These data are supported by various studies, while others show shorter times, probably due to different monitoring techniques. In spite of the pharmacodynamic differences between suxamethonium and rocuronium, the intubating conditions after administration of both compounds are comparable and develop at the same rate.

Adolescent↗
PubMed1991

Beneficial effect of therapeutic infusion of nafamostat mesilate (FUT-175) on hemodynamics in experimental acute pancreatitis.

Acute pancreatitis was induced in 13 anesthetized dogs by retrograde injection of bile mixed with trypsin into the pancreatic duct. Six animals were treated with intravenous infusion of new synthetic antiprotease. Nafamostat Mesilate, at a dose of 1 mg/kg/h. Four out of seven untreated animals died during the experiment. All the treated dogs survived. Hemodynamic data were regularly monitored during a ten-hour observation period. Cardiac output, mean arterial pressure and left ventricular stroke volume decreased rapidly in the untreated animals. An increase in systemic vascular resistance and pulmonary vascular resistance was observed in dogs without treatment. Nafamostat Mesilate given as therapy significantly improved the hemodynamic parameters, and prevented the animals from developing shock. The study demonstrates an advantageous influence of synthetic antiprotease Nafamostat Mesilate on the course of acute experimental pancreatitis.

Acute Disease↗
PubMed1989

Effect on hemodynamics of therapeutic infusion of gabexate mesilate (FOY) in experimental acute pancreatitis.

Acute pancreatitis was induced in ten anesthetized dogs by retrograde injection for bile mixed with trypsin into the pancreatic duct. Five animals were treated with i.v. infusion of gabexate mesilate in a dose of 1 mg/kg per hour. Hemodynamic data were regulary monitored during a 10-h observation period. Cardiac output (CO), mean arterial pressure (MAP), and left ventricular stroke volume (LVSV) decreased rapidly in untreated animals. An increase of systemic vascular resistance (SVR) and pulmonary vascular resistance (PVR) was observed in dogs without treatment. Gabexate mesilate given as a therapy significantly improved the hemodynamic parameters. The study demonstrates an advantageous influence of synthetic antiprotease gabexate mesilate on the course of acute experimental pancreatitis.

Acute Disease↗
PubMed1984

The relationship between human papillomavirus and lower genital intraepithelial neoplasia in immunosuppressed women.

In a group of 20 immunosuppressed women with lower genital neoplasia, evidence of associated human papillomaviral infection was found in all patients on the basis of the histologic identification of koilocytes in the upper strata of areas of mild or moderate dysplasia. Immunohistochemical study of similar areas disclosed human papilloma structural antigens in the lesions in 60%, while 50% had lesions in which human papilloma virions were detected by the electron microscope. An abnormal immunologic status, indicated by an altered T-helper/T-suppressor ratio, a deficient response to mitogenic stimulation, or both, was confirmed in 80% of the patients studied. Twelve of the 20 patients had unusually persistent and recurrent intraepithelial neoplasia, and in one the disorder progressed to invasive epidermoid carcinoma. The progressive behavior of human papillomavirus-associated neoplasia in these immunosuppressed patients might represent an accelerated version of the long-term course of such lesions in immunocompetent hosts.

Adolescent↗
PubMed1983

Association of human papillomavirus infection with cervical intraepithelial neoplasia.

Human papillomavirus infections of the cervix were assessed in patients attending a colposcopy clinic. Of 348 patients with cervical biopsies, 134 (38.5%) had human papillomavirus infections, and of 251 patients with cervical intraepithelial neoplasia (CIN) 112 (44.6%) had human papillomavirus. The majority of patients with human papillomavirus had concurrent CIN (83.6%; 112/134). Patients with human papillomavirus were significantly younger than patients without human papillomavirus (24.4 versus 29.9 years mean age; P less than .001), had significantly milder degrees of CIN (84% versus 43% mild/moderate dysplasia; P less than .001), and had a significantly lower mean number of pregnancies (2.16 versus 3.05; P less than .001). A matched pairs analysis of 69 pairs showed the same distribution of CIN in both human papillomavirus and nonhuman papillomavirus patients. Electron microscopy of human papillomavirus--specific koilocytes confirmed the presence of human papillomavirus particles in the nuclei.

Adult↗