Intracochlear vestibular schwannoma: a potential source for recurrence after translabyrinthine resection.
Explore the source record for details and available documents.
Ear Neoplasms↗
Biomedical subjects
R Reimer
Publications and source records attributed to R Reimer.
[Techniques for postoperative monitoring of tissue circulation after free microvascular tissue transplantation].
Success rates after free tissue transplantation (FTT) have greatly improved over the last 20 years, partly due to improved technical performance of microvascular anastomoses with better optical and instrumental aids. However, flap failure is still a clinical problem and occurs in 5 to 10%, mainly due to blood vessel thrombosis within the first 24 postoperative hours. The clinical results after FTT can be optimized by in-time diagnosis of irreversibly compromised tissue blood flow and immediate operative reexploration. Therefore, there is a special demand for adequate and reliable postoperative monitoring techniques. This article reviews all monitoring techniques which have been performed in the experimental-clinical setting after FTT thus far.
Follow-Up Studies↗
Genetically modified fibroblasts induce angiogenesis in the rat epigastric island flap.
METHODS: Gene therapy was tested for inducing functional angiogenesis in the superficial rat epigastric island flap to allow earlier pedicle division. Autologous rat fibroblasts were grown, harvested, cultured and retrovirally transfected to produce platelet-derived growth factor AA (PDGF-AA), an angiogenetically active protein. Stable gene expression was monitored by PDGF-AA enzyme-linked immunosorbent assay (ELISA). One hundred and eighty animals were divided into three groups (I-III) and a bilateral flap created in each animal. In all experiments, the right-sided flap was subjected to experimental treatment and the left-sided flap served as control (1ml saline 0.9%). During flap elevation, group I received 5X10(6) GMFB (genetically modified fibroblasts) plus 1 ml Dulbecco's modified Eagle's medium. Group II was treated with 5x10(6) NMFB (non-modified fibroblasts) plus 1 ml medium and group III received 1 ml medium only. The flaps were sutured back and the vascular pedicle was bilaterally ligated and divided in each of ten animals during the following 6 days. After 7 days, the flaps were harvested, the amount of necrosis measured and histologically examined. RESULTS: The GMFB produced up to 560 times more PDGF-AA than the NMFB, measured by ELISA. The GMFB-treated flaps tolerated surgical division of the vascular pedicle significantly earlier than groups II and III. Histologically, fibroblasts persisted in all flaps of groups I and II, without major inflammatory reaction. In all GMFB-treated flaps, massive angiogenesis could be demonstrated. CONCLUSION: By means of retroviral gene transfer, autologous rat fibroblasts can be genetically modified for stable expression of the PDGF-A gene to produce high amounts of PDGF-AA, which is angiogenetically active. After injection into the panniculus carnosus, these cells induce functional angiogenesis to permit earlier division of the vascular pedicle in this flap model.
Animals↗
Ventriculoperitoneal shunt placement with video-laparoscopic guidance.
Explore the source record for details and available documents.
Adult↗
Vestibular dysfunction due to cryptococcal meningitis.
Explore the source record for details and available documents.
Adult↗
Postoperative blood flow monitoring after free-tissue transfer by means of the hydrogen clearance technique.
The hydrogen clearance technique was introduced for monitoring postoperative blood flow after free-tissue transfer in this prospective clinical study. This technique allows unlimited repeatable quantitative measurements of tissue blood flow in milliliters per minute per 100 gm of tissue at any site including buried flaps. In this study a real-time blood flow measuring system (Ameflow, Ameda, Switzerland) was employed. Two thousand eight hundred and twenty-three blood flow measurements were carried out on 72 free-tissue transfers, which were performed on 71 patients. Nine of these 72 flaps showed vascular complications (12.5 percent), including arterial thrombosis in 6.9 percent (n = 5), hematoma in 4.2 percent (n = 3), and venous thrombosis in 1.4 percent (n = 1). Complications as well as uneventful postoperative cases were monitored correctly by the hydrogen clearance technique in all cases, reaching sensitivity and specificity values of 1.0 for this technique in our study. Furthermore, all complications could be detected earlier by the hydrogen clearance technique than by clinical monitoring alone, which allowed flap salvation in 7 of 9 cases and a resulting permanent failure rate of free-tissue transfer of 2.8 percent (n = 2). From our data we conclude that the hydrogen clearance technique is a promising tool for postoperative blood flow monitoring after free-tissue transfer. For experimental pathophysiologic and pharmacologic studies of tissue blood flow in flaps, further evaluation of our measuring device including comparative studies with other established techniques is highly recommended.
Adolescent↗
Cultured gastric parietal cells from the guinea pig: adherence, cell growth and stimulus coupling of Ca2+ and cyclic AMP.
The aim of the study was to establish cell culture conditions for responsive guinea pig parietal cells. Parietal cells were isolated by a pronase/collagenase method, enriched by counterflow elutriation and cultured on plastic culture dishes in minimum essential medium. Precoating with gelatine or collagen increased adherence; optimum fetal calf serum concentration was 10%. Parietal cells were cultured for up to 120 h. Intracellular calcium levels in cells cultured for 48 h were 150 nmol/l and increased to 320 nmol/l after stimulation with carbachol and to 250 nmol/l after histamine stimulation as determined by video imaging microscopy. Intracellular cyclic AMP levels were increased 9-fold by histamine in cells cultured for 24 h and more than 30-fold in cells cultured for 48 h. The results show that guinea pig parietal cells grow in primary culture and are suitable for studying second messenger coupling.
Animals↗
Bicarbonate secretion in the guinea pig duodenum: functional characterization of peptide hormone receptors in duodenal enterocytes.
To get information about the peptide hormone receptors involved in duodenal bicarbonate secretion (DBS) and their cellular location, we determined DBS and adenylate cyclase (AC) activity in response to hormones of the vasoactive intestinal polypeptide (VIP)/secretin family of peptides. DBS was determined in an isolated, perfused (24 mmol/1 NaHCO3) loop of the proximal duodenum in urethane- and indometacin-treated guinea pigs. AC stimulation was measured in isolated, homogenized duodenal enterocytes, the histological evaluation of which revealed their villous origin. VIP (10(-9) to 10(-7) mol x kg-1) dose-dependently increased DBS 3.5-fold (p < 0.01); this effect was completely inhibited by the VIP antagonist [D-p-Cl-Phe6,Leu17]VIP (10(-6) mol x kg-1). Glucagon (10(-8) to 10(-6) mol x kg-1) increased DBS 2.1-fold, while secretin (10(-9) to 10(-6) mol x kg-1) had no effect on DBS, but stimulated pancreatic bicarbonate secretion. VIP concentration-dependently increased AC activity 5.6-fold with an EC50 of 1.3 x 10(-9) mol/l. [D-p-Cl-Phe6,Leu17]VIP caused a rightward shift of the VIP concentration-response curve. A Schild plot analysis yielded a slope of 0.85 +/- 0.11, indicating competitive inhibition. While secretin also stimulated AC activity, although 1,000-fold less potent than VIP, glucagon was ineffective. These data indicate that specific VIP receptors, which mediate VIP-stimulated bicarbonate secretion, are present on villous enterocytes. Stimulation of AC by secretin seems to be of pharmacological relevance only and is consistent with the lack of effect of this hormone on DBS. Glucagon likely activates a second transmitter of bicarbonate secretion, or works independently of AC.
Adenylyl Cyclases↗
Role of protein kinase C in duodenal mucosal bicarbonate secretion in the guinea pig.
Since duodenal bicarbonate secretion (DBS) is increased by m-cholinoceptor agonists, it was postulated that protein kinase C (PKC) has a role in this secretion. This premise was examined in guinea pigs, using 12-O-tetradecanoyl-phorbol 13-acetate (TPA) to stimulate bicarbonate production in the perfused duodenum in vivo, and to activate PKC in isolated duodenal enterocytes. TPA (10(-7) mol.kg-1) infused intravenously stimulated active DBS from basal values of 3.64 +/- 0.66 to 8.73 +/- 1.59 mumol.cm-1.10 min-1. This effect was completely blocked by verapamil (4 x 10(-7) mol.kg-1). PKC activity in duodenal enterocytes in the basal state was most abundant in the cytosolic fraction (2,221 +/- 444 U/mg protein) and very low in the particulate fraction (227 +/- 51 U/mg protein). TPA (10(-7) mol.kg-1) caused a time-dependent translocation of the cytosolic, lipid-dependent activity of PKC into the particulate fraction. The effect was maximal at 5 min incubation and was reversed by 30 min. In the particulate fraction, this activity was no longer lipid-dependent, but could be stimulated by Ca2+ alone. These data support the hypothesis that translocation of PKC may contribute to DBS.
Animals↗
Measurements of tissue blood flow by the hydrogen clearance technique (HCT): a comparative study including laser Doppler flowmetry (LDF) and the Erlangen micro-lightguide spectrophotometer (EMPHO).
The purpose of this study was to compare the hydrogen clearance technique (HCT) with two different, well-established techniques, i.e., the laser Doppler flowmetry (LDF) and the Erlangen micro-lightguide spectrophotometer (EMPHO), for tissue blood flow measurements in an experimental setting. For the animal experiments, we chose a rat model for arterial and venous flap thrombosis, using the epigastric groin flap. Forty male dark Aguty rats were included in the study. The animals were divided into eight groups, each with a different vascular thrombotic model. HCT was used to collect 1,467 measurements, and 2,934 graphs were recorded; 27 measurements (54 graphs) had to be discarded due to faulty electrode placements and electronic noise. In 19 of the 27 discarded measurements the cause of failure was moving of the awaking animal with disruption of the decay signal. The LDF and EMPHO measurements were performed continuously during each measuring phase. Simple and multiple linear regression and paired t-tests were used to compare the three techniques. The reproducibility of registered blood flow values in phases 1, 3, 6 and 7 varied between 7.8% and 13.6% which is in about the same range as LDF and EMPHO. We could not find a significant difference between the three techniques in this regard. The correlation coefficient for HCT and LDF was r = 0.89. For HCT and EMPHO we found r = 0.67. Sensitivity and specificity values for HCT were both 1.0 in detecting arterial and venous flap thrombosis; for LDF we found values of 0.89 and 0.92, respectively. Sensitivity and specificity values for EMPHO were 0.92 and 0.95, respectively. After careful evaluation of three different techniques (HCT, LDF, and EMPHO) for measurements of local tissue blood flow we came to the conclusion that HCT must be favoured as a reliable tool for quantitative measurement of local tissue blood flow and early diagnosis of arterial and venous flap thrombosis.
Animals↗
Effect of somatostatin-14 on duodenal mucosal bicarbonate secretion in guinea pigs.
The role of somatostatin-14 in duodenal mucosal HCO3- secretion was investigated in anesthetized, indomethacin-treated guinea pigs. Net HCO3- output from the isolated, perfused (24 mM NaHCO3 + 130 mM NaCl) proximal duodenum was measured during intravenous infusion (alone or in combination) of somatostatin-14, carbachol, vasoactive intestinal peptide (VIP), and prostaglandin E2 (PGE2). In homogenates of duodenal enterocytes, the effect of these agents on adenylate cyclase activity was studied. Basal duodenal HCO3- secretion (3.5 +/- 0.2 mumol/cm/10 min) was reduced dose dependently by somatostatin-14 (10(-11) mol/kg, 10(-9) mol/kg, and 10(-7) mol/kg). Carbachol, VIP, and PGE2 (all 10(-8) mol/kg) increased basal duodenal HCO3- secretion two- to threefold. Somatostatin-14 (10(-7) mol/kg) abolished the stimulatory effect of carbachol and VIP, but not that of PGE2. Basal adenylate cyclase activity in isolated duodenal enterocytes (9.4 +/- 1.0 pmol cAMP/mg protein/min) was unaltered by somatostatin (10(-6) mol/liter) or carbachol (10(-3) mol/liter). VIP (10(-8) mol/liter) and PGE2 (10(-7) mol/liter) increased adenylate cyclase activity two- to threefold, and these effects were unchanged by somatostatin-14 (10(-6) mol/liter). In conclusion, somatostatin-14 inhibits basal and carbachol- and VIP-stimulated duodenal HCO3- secretion, and its mechanism of action is not via inhibition of adenylate cyclase activity in duodenal enterocytes.
Adenylyl Cyclases↗
Analysis of early failures after lumbar decompressive laminectomy for spinal stenosis.
OBJECTIVE: To determine why some patients have no improvement after surgical treatment of lumbar spinal stenosis. DESIGN: We conducted a retrospective study of patients who were referred to our institution between 1990 and 1993 because their symptoms were unchanged or worsened after lumbar decompressive laminectomy. MATERIAL AND METHODS: For the 45 study patients (25 women and 20 men; mean age, 70.8 years), preoperative and postoperative clinical status, preoperative and postoperative imaging studies, and operative reports were analyzed. RESULTS: Preoperatively, only 23 patients (51%) had the clinical syndrome of neurogenic claudication, and 15 (33%) had midline low-back pain without a radicular component. Three other patients had peripheral neuropathy, and three had atypical leg pain. Only 10 patients had radiographic evidence of severe lumbar canal stenosis; the others had moderate, mild, or no stenosis. In 10 patients, surgical decompression was inadequate. Only three patients had the triad of neurogenic claudication, radiographically confirmed severe lumbar stenosis, and adequate decompression of the lumbar canal and lateral recesses. CONCLUSION: The most common pattern in patients with early failure after lumbar laminectomy was the absence of actual neurogenic claudication coupled with the absence of severe stenosis on preoperative imaging studies. The most common technical error was inadequate neural decompression. These data suggest that the outcome may be improved by more careful selection of patients and by performance of an adequate surgical decompression.
Aged↗
Blepharophimosis syndrome is linked to chromosome 3q.
Blepharophimosis syndrome (BPES, blepharophimosis eyelid syndrome) is a distinctive congenital eyelid malformation which can occur sporadically or be inherited in an autosomal dominant fashion. Previous reports have described associated cytogenetic abnormalities on chromosome 3q. We have ascertained and sampled two BPES families with apparent autosomal dominant inheritance and have tested for linkage with 17 polymorphic markers on 3q. Multipoint analysis generated a maximum LOD score of 3.23 using the markers RHO, ACPP and D3S1238. No evidence of genetic heterogeneity was observed. These studies provide the first non-cytogenetic evidence that a defective gene responsible for BPES is located on 3q22.
Blepharophimosis↗
Role of carbonic anhydrase in basal and stimulated bicarbonate secretion by the guinea pig duodenum.
The role of carbonic anhydrase in the process of proximal duodenal mucosal bicarbonate secretion was investigated in the guinea pig. In a series of experiments in vivo, the duodenum was perfused with 24 mmol/liter NaHCO3 solution (+ NaCl for isotonicity) to ensure that active duodenal HCO3- secretion against a concentration gradient was measured. Acetazolamide (80 mg/kg) was infused intravenously to examine the role of carbonic anhydrase on basal and agonist-stimulated HCO3- secretion. Acetazolamide abolished basal HCO3- secretion and significantly decreased HCO3- secretion after stimulation with dibutyryl 5'-cyclic adenosine monophosphate (dBcAMP, 10(-5) mol/kg), dibutyryl 5'-cyclic guanosine monophosphate (dBcGMP, 10(-5) mol/kg), prostaglandin E2 (PGE2, 10(-6) mol/kg), PGF2 alpha (10(-6) mol/kg), tetradecanoyl-phorbol-acetate (TPA, 10(-7) mol/kg), glucagon (10(-7) mol/kg), vasoactive intestinal polypeptide (VIP, 10(-8) mol/kg), and carbachol (10(-8) mol/kg). Utilizing a fluorescence technique, we could detect the enzyme carbonic anhydrase in equal amounts in villous and crypt cells of the proximal duodenal epithelium; no activity was demonstrated in tissues pretreated with acetazolamide. In conclusion, carbonic anhydrase is required for both basal and stimulated duodenal HCO3- secretion.
Acetazolamide↗
Comparative activities of agonists of active duodenal bicarbonate secretion in the guinea pig.
The comparative activity of agonists of duodenal bicarbonate secretion was studied in the anesthetized guinea pig, where the duodenal lumen was perfused with 24 mmol/l NaHCO3 to ensure active secretion of bicarbonate. Agonists were infused alone and in combination. Dibutyryl 3',5'-cyclic adenosine monophosphate, vasoactive intestinal polypeptide (VIP) and prostaglandin E2 (PGE2) were strong stimulants of bicarbonate secretion. Theophylline, dibutyryl 3',5'-cyclic guanosine monophosphate, glucagon and prostaglandin F2 alpha (PGF2 alpha) were weaker agonists, and secretin had no effect. Combinations of any two of VIP, PGE2 and glucagon depressed bicarbonate secretion, whereas combinations of PGE2 and PGF2 alpha, VIP and PGE2, and glucagon and PGF2 alpha increased bicarbonate secretion. The data indicate that cAMP and other secondary messengers may mediate duodenal bicarbonate secretion.
Adenosine Monophosphate↗
Cyclic adenosine monophosphate is the second messenger of prostaglandin E2- and vasoactive intestinal polypeptide-stimulated active bicarbonate secretion by guinea-pig duodenum.
In a guinea-pig model we determined the intracellular events mediating the response of duodenal epithelial cells to vasoactive intestinal polypeptide (VIP) and prostaglandin (PG) E2. Intravenous administration of VIP (10(-9) to 10(-7) mol/kg) and PGE2 (10(-9) to 10(-6) mol/kg) dose-dependently increased duodenal epithelial bicarbonate secretion against an HCO3- concentration gradient, measured by a luminal perfusion technique, in anaesthetized guinea-pigs up to 4.5-fold. This secretion could be mimicked by intraduodenal dibutyryl cyclic adenosine monophosphate (dBcAMP; 10(-9) to 10(-7) mol/kg). Secretin (10(-9) mol/kg) and PGF 2 alpha (10(-9) to 10(-7) mol/kg), both given intravenously, were without effect or considerably less efficient. For VIP and PGE2, specific receptors coupled to adenylate cyclase could be demonstrated in homogenates of isolated duodenal epithelial cells. VIP and PGE2 stimulated adenylate cyclase activity up to sixfold, whereas PGF2 alpha and secretin were considerably less potent and efficient. VIP and PGE2 increased intracellular cyclic AMP levels up to fivefold and ninefold, respectively. This was followed by an increase in cytosolic protein kinase A activity. Bicarbonate secretion was maximal at 30 min. Examination of the subcellular distribution of protein kinase A showed a predominant cytosolic location. These data support the notion the PGE2 and VIP cause bicarbonate secretion by the serial activation of adenylate cyclase and protein kinase A in duodenal epithelial cells.
Adenylyl Cyclases↗
Surgical treatment of spontaneous intracranial hypotension associated with a spinal arachnoid diverticulum. Case report.
The authors present the case of a 22-year-old woman who developed spontaneous intracranial hypotension as a result of a cerebrospinal fluid leak from a thoracic extradural arachnoid diverticulum. The patient was successfully treated by ligation of the diverticulum. The entity of spontaneous intracranial hypotension and its relevance to neurosurgery are discussed.
Adult↗
Laparoscopic placement of ventriculoperitoneal shunts: preliminary report.
We used a laparoscopic technique for the percutaneous placement of the peritoneal end of cerebrospinal fluid shunts in adult patients with obstructive or normal-pressure hydrocephalus. Concurrent with the initial cranial part of the procedure, pneumoperitoneum is established in a routine fashion, and a video-laparoscope and grasping forceps are inserted into the peritoneal cavity. With use of a pacemaker introducer kit, the peritoneal catheter is placed percutaneously under direct laparoscopic vision through a small upper abdominal incision into the peritoneal cavity. At the completion of the procedure, the patency of the assembled shunt system can be verified by observing free flow of cerebrospinal fluid from the catheter tip as the valve is being pumped. We found that this technique is particularly useful in technically challenging cases--for example, those involving obese patients and those who have undergone multiple abdominal operations. No complications associated with the technique were encountered.
Adult↗