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Biomedical subjects

T Koch

Publications and source records attributed to T Koch.

At least 235 records · Page 13Linked to original sources
PubMed1989

[The relevance of sonographic diagnosis of cervical lymph nodes in tumors of the head and neck].

Thirty patients with a squamous cell carcinoma of the head and neck, with cervical lymph nodes which could be shown by ultrasound but not by palpation of the neck, are reviewed. The cervical lymphatic nodes, which were similar in size to the preoperative ultrasonic measurement, were removed by elective neck dissection. Histological examination showed a reactive inflammation only, without tumour infiltration, in 83.3% of the cases. These clinically inconspicious lymph nodes, which were homogeneous on ultrasound scan and could be easily differentiated from the background, obviously show the premalignant stage of tumour spread. The consequences for the operation and later follow-up are discussed.

Biopsy↗
PubMed1989

[Sonographic diagnosis and differential diagnosis of neck cysts].

We report 101 patients with the clinical diagnosis of a branchial cyst investigated by ultrasonography. In 78 cases the diagnosis of a branchial cyst was confirmed by the ultrasound findings. The picture of a typical cyst was found in 26 cases, whereas a complex cyst filled with sludge or debris was found in 52 patients. Histology revealed a different diagnosis in 7 cases of ultrasonic complex cysts. Of 23 patients where a branchial cyst was excluded by ultrasound, histology showed a lesion other than a branchial cyst in 19 cases. In total, only 34.6% of the histologically confirmed branchial cysts displayed the typical signs of such a cyst on ultrasonography. However, in 91% of the patients with an actual branchial cyst we were able to confirm the diagnosis by ultrasound before operation. The differential diagnosis of other benign and malignant lesions of the neck resembling branchial cysts is discussed with examples.

Branchioma↗
PubMed1988

Adenylate cyclase and G-proteins as a signal transfer system in the guinea pig inner ear.

In many eukaryotic cells G-proteins play a key role in signal transduction through outer cell membranes. To study this pathway in the auditory organ of mammals we examined tissue preparations from the stria vascularis and the organ of Corti from the guinea pig inner ear. The activity of adenylate cyclase was measured by stimulation at the site of the enzyme, the hormone receptors and the modulating G-proteins. In the organ of Corti we found a low enzyme activity in all cochlear turns. The stria vascularis, however, showed a constant high concentration of beta 2-adrenergic receptors and of stimulating G-proteins in all cochlear turns. In contrast, the activity of the enzyme increased from the apical to the basal turn. Adenylate cyclase could be stimulated or inhibited in a concentration-dependent manner by drugs selectively effecting the G-proteins. Our results suggest a structure of the adenylate cyclase complex in the inner ear similar to other organs. Pathophysiological correlations to hearing loss associated with pseudohypoparathyroidism are discussed.

Adenylyl Cyclases↗
PubMed1988

Termination of malignant ventricular tachycardias by use of an automatical defibrillator (AICD) in combination with an antitachycardial pacemaker.

We implanted an "Automatic Implantable Converter-Defibrillator" (AICD) and as far as useful an antitachycardial pacemaker (Intertach) in addition in 11 patients suffering from malignant ventricular tachycardias via a median sternotomy. In eight cases a coronary artery disease and in three cases a dilatative myopathy was the intrinsic disease. During surgery in all patients we attempted to trigger ventricular tachycardias and their termination by programmed stimulation. This procedure was successful in nine patients who received an antitachycardial pacemaker system. After the wounds healing, repeated induced ventricular tachycardias in all patients, who received a combination of the systems, could be terminated by the antitachycardial pacemaker prior to an intervention of the implanted defibrillator.

Cardiac Pacing, Artificial↗
PubMed1988

Structure and function of Fc receptors on macrophages and lymphocytes.

Cell surface receptors for the Fc portion of immunoglobulin confer on most cells of the immune system the ability to communicate with the humoral antibody response. These Fc receptors are known to be particularly important for the function of various effector cells, such as macrophages, since they are involved in mediating a variety of activities including endocytosis, antibody-dependent cellular cytotoxicity, and triggering the release of potent inflammatory agents. Over the past few years, a considerable amount has been learned about the structure and functions of the Fc receptors expressed by murine and human cells, due to the availability of specific anti-receptor antibodies and the isolation of Fc receptor cDNA clones. In general, these receptors are transmembrane proteins whose extracellular domains contain two immunoglobulin-like regions and are thus members of the immunoglobulin gene family. Their domain structure consists of a glycosylated extracellular domain, a single membrane-spanning segment, and a relatively long cytoplasmic domain. The cytoplasmic tails exhibit a surprising degree of variation in length and amino acid sequence. This review summarizes some recent information concerning the structure and expression of the Fc receptors found on murine and human macrophages and lymphocytes. Particular attention is paid to the functional activities of these receptors, and the possible relationship between receptor function and receptor structure.

Animals↗
PubMed1987

Isolation and expression of cDNA clones encoding a human receptor for IgG (Fc gamma RII).

We have cloned and expressed a cDNA encoding a human receptor for IgG (Fc gamma R) from the monocyte cell line U937. The deduced structure is a 35-kD transmembrane protein with homology to the mouse Fc[gamma 2b/gamma 1] receptor amino acid sequence of approximately 60% in the extracellular domain. The signal sequence is homologous to the mouse Fc gamma R alpha cDNA clone, while the transmembrane domain shares homology with mouse Fc gamma R beta cDNAs. The cytoplasmic domain is apparently unique. The extracellular domain shows significant homology to proteins of the Ig gene superfamily, including the human c-fms protooncogene/CSF-1 receptor. Mouse Ltk- cells transfected with the human Fc gamma R cDNA express a cell-surface receptor that selectively binds human IgG and is recognized by the anti-Fc gamma RII mAb IV.3. Antibodies against peptides derived from the human Fc gamma R sequence specifically stain U937 cells, but not an Fc gamma RII-bearing B-lymphoblastoid cell line (Daudi). These results identify the human Fc gamma RII as the homologue of mouse Fc[gamma 2b/gamma 1] R, and provide evidence for heterogeneity of Fc gamma RII expressed on monocytes and B cells.

Amino Acid Sequence↗
PubMed1987

Indicators of perinatal asphyxia.

Creatinine phosphokinase and its isoenzymes (myocardial-specific MB and brain-specific BB) are elevated in the presence of specific tissue injury. The value of this serum marker as an objective indicator of perinatal asphyxia was studied. Forty-nine patients with gestational ages ranging from 36 to 42 weeks were prospectively studied. Patients who by interpretation of the fetal heart rate tracing alone were diagnosed as having fetal distress demonstrated significantly lower pH (p = 0.001) and base excess (p less than 0.0001) in umbilical venous blood. Umbilical venous cord MB (p less than 0.05) and BB (p less than 0.01) were increased in this group. Abnormal fetal heart rate patterns correlate well with acid-base abnormalities and elevated creatinine phosphokinase values. These tests may demonstrate more efficient and improved indicators of tissue injury and damage from perinatal asphyxia than clinical observation alone.

Acid-Base Equilibrium↗
PubMed1987

Replication of adeno-associated virus in synchronized cells without the addition of a helper virus.

We investigated the helper-independent replication of adeno-associated virus (AAV) in cells synchronized by pretreatment with hydroxyurea, reversal of polyamine depletion, or physical mitotic detachment. In Chinese hamster cells (OD4 line) treated with hydroxyurea prior to infection. AAV underwent a complete cycle of replication. Transfection of such cells with plasmid-cloned AAV DNAs also gave rise to infectious viral progeny. Synchronization of OD4 cells by reversal of polyamine depletion or mitotic detachment led to independent AAV DNA synthesis (and infectious viral progeny in the case of the former procedure), but these procedures were not as effective as hydroxyurea pretreatment. Independent AAV DNA synthesis was also detected in some other cell lines of Chinese hamster, human, and monkey origin treated with hydroxyurea prior to infection. The results demonstrate that, in contrast to previous notions, the AAV infectious process is not absolutely dependent upon the addition of a coinfecting helper virus.

Animals↗
PubMed1987

MR imaging of intracranial tuberous sclerosis.

The role of MR in evaluating tuberous sclerosis is reviewed in 15 patients. These studies were compared with CT scans, which were available in 14 patients. Four characteristic findings were noted on the MR images obtained. Subependymal nodules projecting into the lateral ventricles were seen in 12 of 15 patients on T1-weighted images. This was the most specific finding. Distortion of the normal cortical architecture was seen in 10 of 11 patients in whom T1-weighted images were obtained using a 256 X 256 matrix. These foci corresponded to multiple cortical areas of increased signal on T2-weighted images. Dilated ventricles were seen in five patients. In one patient, a known astrocytoma showed increased signal on the T2-weighted images, allowing differentiation from a benign subependymal nodule. MR depicted the cortical hamartomas more completely than did CT. The MR scans were abnormal in all cases, and a diagnosis could be confidently made in all 11 cases scanned using a 256 X 256 matrix. Our preliminary experience suggests that MR will at least equal and probably exceed CT, both for sensitivity and specificity, given the use of a 256 X 256 matrix.

Adolescent↗
PubMed1986

Biliary excretion of gamma-glutamyltransferase. Selective enhancement by acute ethanol administration.

To study the acute effect of ethanol on various constituents of the bile, female Wistar rats received by intravenous administration 0.9% NaCl solution either alone or containing in addition ethanol (0.1 ml ethanol 96% hr-1 100 g body weight-1). Compared to saline-treated controls there was a significant enhancement of biliary gamma-glutamyltransferase excretion after ethanol infusion for 5 hr by 166% (22.1 +/- 2.8 microU/min/100 g body weight vs. 58.2 +/- 13.7; P less than 0.0125), whereas no changes or only marginal alterations have been observed for bile flow and the biliary excretion of total bile acids and alkaline phosphatase. The selective enhancement of biliary gamma-glutamyltransferase excretion by ethanol can be ascribed to an increased solubilization of the membrane-bound enzyme originating from the bile canaliculi of the hepatocytes and/or the epithelial cells of the bile ducts. Since the biliary excretion of total bile acids remained unchanged by ethanol, the observed selective solubilization of gamma-glutamyltransferase may occur by a mechanism primarily not involving total bile acids and could be linked to a direct effect of ethanol on physico-chemical properties such as an increased fluidity of liver plasma membranes.

Alkaline Phosphatase↗
PubMed1986

[Method for the direct comparison of the frequency behavior in QT- and activity-controlled pacemaker systems].

A non-invasive method of testing the suitability of an activity-controlled pacemaker system in patients with VVT-programmable systems is presented. The QT-time controlled TX-pacemaker of a 36-year-old patient was programmed into the VVT-mode. Then the activity-controlled pacemaker (Activitrax) was fixed epicutaneously above the pectoral muscles and two stimulation electrodes were applied above the implanted pacer and the tip of the implanted probe. Thus the external could be made to trigger the implanted system. The frequency profile was recorded with identical loads with QT and/or activity control. For both the frequency-adapted pacemaker systems, the direct comparison yields characteristic frequency profiles: a quick frequency increase and decrease of both Activitrax and load, but a delayed frequency profile of the QT-controlled pacer. Different frequency maxima are rendered by the two pacemakers as a function of the load.

Adult↗
PubMed1984

The long terminal repeat of an endogenous intracisternal A-particle gene functions as a promoter when introduced into eucaryotic cells by transfection.

We describe experiments designed to determine whether an endogenous intracisternal A-particle (IAP) gene randomly selected from a mouse embryo library has the potential to be transcriptionally active. Assays for IAP gene transcription were done with permanently transformed rat cells and transiently transfected monkey and mouse cells. The rat cells, which had integrated IAP gene copies, contained IAP RNA. A start site within the IAP 5' long terminal repeat (LTR) was localized by S1 mapping. The promoter activity of the IAP LTR was also measured in cells 48 h after the introduction of recombinant plasmids in which bacterial chloramphenicol acetyl transferase (CAT) encoding sequences were under the control of the LTR. The IAP LTR promoted CAT activity in mouse and monkey cells. In mouse L-cells, the levels of CAT activity were 10 to 25% of those promoted by an analogous recombinant containing the Moloney murine sarcoma virus LTR as the promoter. In contrast to the Moloney murine sarcoma virus LTR, the IAP LTR was five- to eightfold more active in monkey cells than in mouse cells. The 5' and 3' LTRs were equally active, and promoter activity was dependent on having the orientation of the LTRs with respect to the CAT gene the same as their orientation with respect to the IAP gene. A 5'-flanking sequence containing a member of the highly repetitive R-sequence family increased CAT activity in COS cells 11-fold when present along with the LTR. Our results indicate that the LTR of an endogenous mouse IAP gene can function as an efficient promoter in heterologous as well as homologous cells.

Acetyltransferases↗
PubMed1984

[Peridural anesthesia with etidocaine. Clinical studies on the effect of vasoconstrictors on sensory and motor blockade].

In a randomized double-blind study etidocaine 1.5% without a vasoconstrictor (n = 10), with adrenaline 1:200,000 (n = 10) and with ornipressine 1 IU/10 ml (n = 10) were administered epidurally to 30 orthopaedic patients. Sensory blockade was tested with electric pain stimuli; motor blockade was assessed with dynamometry during isometric plantar flexion of the foot and with the Bromage score; the intraoperative analgesia was determined as well. The development of sensory and motor blockade became faster and more intensive by addition of the two vasoconstrictors. The intraoperative analgesia, insufficient without vasoconstrictors, however, not to full satisfaction. Adrenaline improved the effects of etidocaine more than did ornipressine . The sole use of etidocaine without and with vasoconstrictors is not recommended for epidural anaesthesia for surgery of the lower extremities. It is the local anaesthetic of choice for intensifying motor blockade during already achieved analgesia.

Acetanilides↗