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Biomedical subjects

J Thomsen

Publications and source records attributed to J Thomsen.

At least 19 recordsLinked to original sources
PubMed1992

Medial acoustic neuromas. A new clinical entity.

The medial acoustic neuroma, a new clinical entity, is defined as an extrameatal tumor without tumor mass laterally in the internal acoustic meatus. During a 12-year period in Denmark, in a prospective analysis of 400 acoustic neuromas on which surgery was performed by the translabyrinthine approach, 48 tumors (12%) were medial tumors, corresponding to an incidence of 0.8 tumors per million inhabitants per year. Analysis of the symptoms and results showed that medial tumors are generally larger with more severe involvement of the cerebellum, the trigeminal nerve, and the brain stem, compared with the 352 nonmedial tumors. Because of its onset in the medial part of the vestibular nerve, the tumor may grow silently and to a considerable size without any widening of the internal auditory canal and with relatively good hearing. Meaningful hearing preservation is impossible in medial tumors, because the smallest medial tumor (subject's hearing, 40 dB or better) measured 3 cm, and the majority of tumors are giant tumors.

Adult↗
PubMed1992

Some aspects of life quality after surgery for acoustic neuroma.

This investigation was performed to describe some aspects of the quality of life in subjects after translabyrinthine removal of an acoustic neuroma, resulting in unilateral total deafness. Two hundred ninety-three subjects who had been operated on during 1976 through 1990 and who were living outside the Copenhagen (Denmark) City and County received a postal questionnaire, to which 93% (n = 273) responded: 118 men and 155 women with a median age of 58 years (range, 18 to 81 years). The median observation period from surgery to the questionnaire was 6 years (range, 6 months to 14 years), and the median age at operation was 52 years (range, 15 to 76 years). Among the subjects, 22% had received postoperative hearing rehabilitation with various types of hearing aids in the ear not operated on. In 62%, tinnitus was experienced in the ear with tumor before surgery, and at the time of the questionnaire, 49% experienced tinnitus in the ear operated on. Half a year after surgery, 56% still experienced dizziness. Sixty-four percent reported damage to the facial nerve in relationship to the operation. At the time of the questionnaire, 12% indicated a total loss of facial nerve function. No vocational consequences were found in 74% after surgery. Information concerning different symptoms related to surgery was insufficient in 29%, while the quality of information in relation to surgery was more satisfying. In conclusion, the study demonstrates that deafness, dysequilibrium, and reduced facial nerve function caused the most severe problems. Improved information to patients before surgery may reduce the frequency of negative experiences.

Adolescent↗
PubMed1992

Development of an optimized refolding process for recombinant Ala-Glu-IGF-1.

Denatured and reduced N-terminal extended insulin-like growth factor-1 (AE-IGF-1) was purified from Escherichia coli extracts and subjected to in vitro folding. The renaturation process was shown to be a function of the redox potential of the solution. Folding by different methods had no significant effect on the renaturation. A maximal yield of 60% (w/w) was obtained. The folded AE-IGF-1 was enzymatically converted to IGF-1. The major by-product (20% w/w) was identified as scrambled IGF-1. Enzymatic digestion at alkaline and acidic pH suggested two possible disulphide bond arrangements; (i) Cys6-Cys47, Cys18-Cys61, Cys48-Cys52; or (ii) Cys6-Cys52, Cys18-Cys61, Cys47 and Cys48 being in their reduced forms. Energy minimization and molecular modelling suggested that the scrambled IGF-1, having reduced cysteines at positions 47 and 48, was the energetically most stable conformation of the two.

Amino Acid Sequence↗
PubMed1992

Causes of facial nerve paresis after translabyrinthine surgery for acoustic neuroma.

Forty-six consecutive video-recorded translabyrinthine operations at Gentofte Hospital, for tumors of 5 to 25 mm, were investigated for possible damage to the facial nerve from cauterization, suction, stretching, pushing, and other instrumental trauma at the following regions: fundus, internal meatus, porus, cerebellopontine angle, and brain stem. House-Brackmann grading of the postoperative facial nerve function was determined from the patient records for the 1st, 3rd, and 10th days and 3 months and 6 months postoperatively, as well as the final status. Suction on the nerve seems to be the most important factor for perioperative facial nerve damage. The most common site of damage was the porus region. This investigation shows thermic drilling lesions to be very relevant. There was no correlation between the degree and character of damage and the postoperative facial nerve function. In eight patients we cannot explain the postoperative facial palsy.

Facial Nerve↗
PubMed1992

Suboccipital acoustic neuroma surgery: results of decentralized neurosurgical tumor removal in Denmark.

From 1979 to 1990, a series of 59 patients with 59 acoustic neuromas were operated on in five departments of neurosurgery by at least five different neurosurgical teams, employing the suboccipital approach. Perioperative mortality rate was 8.5%. Complications including hematoma, ventricular hemorrhage, meningitis, hemiparalysis, abducens nerve paralysis, recurrent nerve paralysis, postoperative wound infection and CSF leak were observed in 21 patients (35.6%). Total tumor removal was not possible in 17 patients (28.8%). Converting the postoperative facial nerve function to House-Brackmann (HB) classification, 34 patients (57.6%) were regarded as HB 6. Reconstruction of the facial nerve was attempted in 19 patients (32.2%). Attempts at hearing preservation were unsuccessful in all patients. Failure to attain better results and the importance of centralized treatment of acoustic neuroma are emphasized.

Adult↗
PubMed1992

Incidence of acoustic neuromas.

The annual incidence of diagnosed acoustic neuromas in Denmark during two 7-year periods from June 1976 to June 1990 was compared, collecting all operated and non-operated tumors from the entire country. During the first period 278 tumors were diagnosed with an annual incidence of 38 tumors or 7.8 tumors per million per year. During the second period the annual incidence rose to 48 tumors and 9.4 tumors per million per year. There was a significant decrease of extrameatal tumor size from 33 to 26 mm and diminishing of giant tumors.

Denmark↗
PubMed1991

Covalent structure of two novel neutrophile leucocyte-derived proteins of porcine and human origin. Neutrophile elastase homologues with strong monocyte and fibroblast chemotactic activities.

The covalent structures of two, novel, neutrophile, leucocyte-derived, strongly basic proteins of porcine and human origin have been determined by microsequencing in combination with time-of-flight plasma desorption mass spectrometry. The porcine protein primary structure of 219 amino acid residues was shown to contain 6 cysteine residues, 2 putative carbohydrate sites and 14% basic residues. The human protein contained 221 amino acid residues of which 8 were cysteine, 4 putative carbohydrate sites and 12% basic. A 47% direct sequence similarity to human neutrophile elastase was found, but due to mutations of two of the three amino acids in the catalytic triad, proteolytic activity is absent. Modelling and alignment studies unveil a close relationship of both proteins to the serine protease family, the greatest similarity being to those serine proteases present in granules from peripheral blood cells. Both proteins have been shown to be chemotactically active for monocytes and fibroblasts in vitro.

Amino Acid Sequence↗
PubMed1991

Heterogeneity in the tyrosine sulfation of Chinese hamster ovary cell produced recombinant FVIII.

By the use of recombinant technology, several stable Chinese hamster ovary (CHO) cell lines expressing human FVIII were established. Thrombin treatment and SDS-PAGE analysis of the purified recombinant FVIII (rFVIII) revealed a striking difference from plasma-derived FVIII (pFVIII). A 43-kDa fragment of the FVIII heavy chain appears as a double band from rFVIII, while a single band from pFVIII is observed. All other fragments from the two samples appeared similar by SDS-PAGE. The heterogeneity is caused by incomplete tyrosine sulfation of one or more of the three potential tyrosine sulfation sites (Tyr718, Tyr719, Tyr723). To investigate if there is a general limitation and heterogeneity in the tyrosine sulfation of rFVIII, two other potential tyrosine sulfation sites on the FVIII light chain (Tyr1664, Tyr1680) were analyzed. The results show that both sites on the pFVIII light chain and on the rFVIII light chain are completely sulfated. The limitation of CHO cells to tyrosine sulfate rFVIII is therefore only restricted to a few sites. The two sulfated forms of rFVIII can easily be separated by ion-exchange chromatography, indicating the importance of the sulfate groups on the charge and/or conformation of FVIII. Both forms of rFVIII possess identical in vitro coagulation activity, von Willebrand factor binding, and thrombin activation profile. However, the difference in tyrosine sulfation may change other biological properties of FVIII.

Animals↗
PubMed1991

Primary sequences of insulin-like growth factors 1 and 2 isolated from porcine plasma.

Insulin-like growth factors 1 and 2 were purified from porcine plasma. In addition to the determination of their isoelectric points, the primary structures of both proteins were determined, using low microgram quantities of protein, by the versatile combination of time-of-flight plasma desorption mass spectrometry and automated Edman degradation. Porcine insulin-like growth factor 1 was shown to be homologous to both human and bovine proteins; the type 2 growth factor showed one mutation to both human and bovine type 2 proteins.

Amino Acid Sequence↗
PubMed1991

Vocal quality of decannulated children following laryngeal reconstruction.

Laryngotracheal reconstruction with expansion surgery is a reliable method for treatment of laryngotracheal stenosis in children. It allows for decannulation of the patient and restoration of vocal communication. Previous information regarding vocal quality in these patients has been scant. Sixteen children who underwent successful laryngotracheal reconstruction were evaluated using a standardized voice assessment during each of the following: phoneme prolongation, counting, storytelling, and spontaneous conversation. Interjudge ratings were obtained to establish reliability. The location and severity of the laryngotracheal stenosis and the method of treatment were reviewed. Twelve children have a functional voice compared to six preoperatively. Overall, vocal parameters suggested a particular pattern consisting of a lower than optimal pitch and a restricted pitch range. Laryngotracheal reconstruction does make oral communication possible for children who would otherwise have persistent tracheotomy. However, vocal quality appears to be disturbed in most of the patients.

Child↗
PubMed1991

Ten-year incidence of myocardial infarction and prognosis after infarction. Department of Veterans Affairs Cooperative Study of Coronary Artery Bypass Surgery.

BACKGROUND: The 10-year incidence of myocardial infarction (fatal and nonfatal) and the prognosis after infarction were evaluated in 686 patients with stable angina who were randomly assigned to medical or surgical treatment in the Veterans Administration Cooperative Study of Coronary Artery Bypass Surgery. METHODS AND RESULTS: Myocardial infarction was defined by either new Q wave findings or clinical symptoms compatible with myocardial infarction accompanied by serum enzyme elevations with or without electrocardiographic findings. Treatment comparisons were made according to original treatment assignment; 35% of the medical cohort had bypass surgery during the 10-year follow-up period. The overall cumulative infarction rate was somewhat higher in patients assigned to surgery (36%) than in medical patients (31%) (p = 0.13) due to perioperative infarctions (13%) and an accelerated infarction rate after the fifth year of follow-up (average, 2.4%/yr in the surgical group versus 1.4%/yr in the medical group). The 10-year cumulative incidence of death or myocardial infarction was also higher in surgical (54%) than in medical (49%) patients (p = 0.20). According to the Cox model, the estimated risk of death after infarction was 59% lower in surgical than in medical patients (p less than 0.0001). The reduction in postinfarction mortality with surgery was most striking in the first month after the event: 99% in the first month (p less than 0.0001) and 49% subsequently (p less than 0.0001). The estimated risk of death in the absence of infarction was nearly identical regardless of treatment (p = 0.75). Exclusion of perioperative infarctions did not alter the findings. CONCLUSIONS: Although surgery does not reduce the incidence of myocardial infarction overall, it does reduce the risk of mortality after infarction, particularly in the first 30 days after the event (fatal infarctions).

Angina Pectoris↗
PubMed1991

Hearing decrease after loss of cerebrospinal fluid. A new hydrops model?

In a prospective study of 12 patients undergoing operation for acoustic neuromas the hearing on the contralateral ear was tested before and systematically day by day after operation. In 11 cases a perceptive loss of at least 20 dB was found at one or more frequencies during the first 2 postoperative weeks. A maximal average threshold decrease of 16.5 dB was found in the treble (2.4, 8 kHz average), while a tendency of a more pronounced decrease of 19.6 dB was seen in the low frequencies (125, 250, 500 Hz average). After 3 months the hearing had normalized in all cases. The explanation for the transitional loss supports the present theory: The loss of cerebro-spinal fluid during operation diminishes the CSF pressure. This decrease is transmitted to the perilymph via the cochlear aqueduct producing a transitory perilymphatic hypotonia, which in turn hydromechanically results in a relative endolymphatic hypertension mimicking an endolymphatic hydrops thus representing a human hydrops model.

Adult↗
PubMed1991

Cerebrospinal fluid leak from nontumor ear after acoustic neuroma surgery: diagnostic and therapeutic problems.

An unusual case of CSF leak from the nontumor ear after removal of a 3-cm acoustic neuroma is presented. Prior to tumor removal a ventricular-peritoneal shunt was established because of increased intracranial pressure. After the shunt was clamped the patient twice developed rhinoliquorrhea and underwent in both instances unsuccessful closure of the leak on the tumor side. Finally the leak was established in the nontumor ear, most likely due to sequelae after a hunting accident 20 years before, where a projectile created a defect in the tegmen tympani. The CSF leak was probably provoked by the pressure changes following tumor removal and shunt treatment.

Brain↗
PubMed1990

Gastrin, cholecystokinin and their precursors in acoustic neuromas.

Using sequence-specific radioimmunoassays the occurrence of 4 neuropeptides (cholecystokinin (CCK), gastrin, somatostatin, substance P and some of their precursors) was examined in 19 human acoustic nerve tumors and corresponding normal tissue. The normal acoustic nerve tissue obtained by autopsy contained traces of CCK, somatostatin, and substance P (less than or equal to 0.5 pmol/g), but neither proCCK, gastrin nor progastrin. In contrast 8 tumors expressed proCCK (range 0.2-4.5 pmol/g), 3 tumors gastrin (0.1-7.3 pmol/g) and 14 tumors progastrin (0.6-2.2 pmol/g). Traces of somatostatin were present in two and substance P in one tumor. The results show that acoustic neuromas often express the homologous CCK and gastrin genes, but process their propeptides poorly to transmitter-active peptides. The tumor synthesis of gastrin/progastrin contrasts to the rare, sporadic expression of the gastrin gene in normal nerve tissue.

Adult↗
PubMed1990

Estrogen and progesterone receptors in acoustic neuromas.

Acoustic neuromas are more frequent, larger, and more vascular in women, and their growth rate increases during pregnancy. Estrogen receptors were claimed to be demonstrated in these neoplasms for the first time in 1981. Since then, numerous diverging studies, using various biochemical and histochemical methods, have been published on the contents of estrogen and progesterone receptors in acoustic neuromas. We determined the content of estrogen and progesterone receptors by means of an immunohistochemical method, using monoclonal antibodies, which has proved to be reliable, reasonably sensitive, and clinically relevant in other tissues, especially in breast carcinomas. No estrogen or progesterone receptors could be found in 18 consecutive acoustic neuromas from 7 men and 11 women, ranging in age from 26 to 73 years. The results do not support preoperative hormone treatment of acoustic neuromas.

Adult↗