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Biomedical subjects

M Becker

Publications and source records attributed to M Becker.

At least 91 records · Page 5Linked to original sources
PubMed1986

Solubilization and degradation of extracellular matrix by various metastatic cell lines derived from a rat rhabdomyosarcoma.

Examination by use of WAG syngeneic female rats was made on 4 rat rhabdomyosarcoma sublines expressing different metastatic potentials for their abilities to degrade proteoglycans and glycoproteins of the extracellular matrix (ECM), deposited by corneal endothelial cells and metabolically labeled with [3H]glycosamine and [35S]sulfate. Of the label incorporated in ECM, 10-20% was released in the culture medium in 3 days by the cell lines studied. The proteoglycans, glycosaminoglycans, and glycoproteins released by the cells from ECM were separated and partially characterized. Most of the ECM glycoproteins were recovered in the region of 200,000 (200K) on gel chromatography. Glycopeptides of 10K-20K apparent molecular weight were minor components. The glycosaminoglycan chains of the proteoheparan sulfate were partially hydrolyzed to 20K fragments. Tumor cells increased also the solubilization of the nondegraded matrix macromolecules. About 5-8% of the radioactivity of the ECM remained associated with the tumor cells detached from the ECM. ECM degrading activity of the sublines did not correlate with their ability to colonize the lungs after iv injection but did correlate with their ability to metastasize to the lungs from the primary subcutaneous site.

Animals↗
PubMed1986

Differential adhesiveness of rhabdomyosarcoma-derived cloned metastatic cell lines to vascular endothelial monolayers.

A series of 11 cloned cell lines derived from a primary, nickel-induced rat rhabdomyosarcoma was evaluated for their metastatic capacity (number of lung colonies following i.v. injection) and attachment kinetics to confluent pig endothelial cell monolayers grown in vitro. The morphology of the adhering cells was also studied by optical and scanning electron microscopy. Cells from all lines tested began to attach to the endothelial monolayers within 15 min of incubation at 37 degrees C, with 64% to 93% of the cells adhering after 2 h. Attachment rates at 30 min ranged from 29 to 48% for four lines classed as "weakly adhesive" (attachment, less than 50%) and from 53 to 78% for seven lines classed as "highly adhesive" (attachment, greater than 50%). Four clones of five displaying low lung-colonizing capacities also showed low attachment rates to endothelial monolayers in vitro. All of six highly colonizing lines studied had high attachment rates. A degree of positive correlation was observed between the amount of cell surface fibronectin as evaluated by immunofluorescence and the early phase attachment rates (and lung-colonizing capabilities) of the different cloned cell lines. Early (15 min) attachment of tumor cells to isolated extracellular matrix preparations proceeded at higher rates than to endothelial monolayers, and previously detected differences between high- and low-colonizing clones were less evident with these matrix substrates. Our results suggest possible interrelationships between specific cell adhesion properties and the metastatic potential of blood-borne tumor cells.

Animals↗
PubMed1986

[Isoenzymes of N-acetyl-beta-D-glucosaminidase (NAG): new method of evaluating the nephrotoxicity of aminosides. Our experience with dibekacin in geriatrics].

To evaluate nephrotoxicity of dibekacin among elderly patients, we studied the daily urinary excretion of NAG and determined isoenzyme levels in the urine of 36 patients (mean age 80 yrs) treated with dibekacin (3 mg.kg-1.day-1). Only two patients developed transient acute renal failure during the first 10 days of treatment. Total NAG urinary activity was however important (304.5 +/- 38.6 U/mmol creat), due primarily to isoenzymes A (58.8 +/- 2.0%) and I (30.8 +/- 1.5%), while B-form excretion was moderately increased (10.3 +/- 1.0%). These results were compared with those obtained with gentamicin (28 patients, 11 transient acute renal failure). The rate of A-form was identical for both antibiotics while excretion of the B-form was significantly higher with gentamicin (p less than 0.001). These results show that nephrotoxic risk is linked to the excretion of the B-form, and allow us to oppose the notion of "functional" enzymuria (low nephrotoxic risk) linked with A- and I-forms with the notion of "lesional" enzymuria (high nephrotoxic risk) linked with the B-form.

Acetylglucosaminidase↗
PubMed1986

Anesthesia in Göttingen miniature swine used for experimental surgery.

This contribution describes a modern technique of producing general anesthesia in the Göttingen minipig. The method of anesthesia selected is dependent on the duration and type of surgery. The drugs used to produce anesthesia should not interfere with the experimental aims, therefore only drugs with well known actions and a standardized anesthesiological procedure should be used. Climazolam, Ketamine and atropine are preferred for induction of anesthesia. After endotracheal intubation, inhalation anesthetic mixed with oxygen and nitrous oxide is used to maintain general anesthesia. Controlled ventilation is necessary to prevent the animals from developing respiratory acidosis. Postoperative analgesia is provided by orally administering acetylsalicylate or morphine-sulfate pentahydrate at 12 hour intervals.

Anesthesia, General↗
PubMed1985

Picosecond kinetics of the initial photochemical electron-transfer reaction in bacterial photosynthetic reaction centers.

The absorption changes that occur in reaction centers of the photosynthetic bacterium Rhodopseudomonas sphaeroides during the initial photochemical electron-transfer reaction have been examined. Measurements were made between 740 and 1300 nm at 295 and 80 K by using a pulse-probe technique with 610-nm, 0.8-ps flashes. An excited singlet state of the bacteriochlorophyll dimer P* was found to give rise to stimulated emission with a spectrum similar to that determined previously for fluorescence from reaction centers. The stimulated emission was used to follow the decay of P*; its lifetime was 4.1 +/- 0.2 ps at 295 K and 2.2 +/- 0.1 ps at 80 K. Within the experimental uncertainty, the absorption changes associated with the formation of a bacteriopheophytin anion, Bph-, develop in concert with the decay of P* at both temperatures, as does the absorption increase near 1250 nm due to the formation of the cation of P, P+. No evidence was found for the formation of a bacteriochlorophyll anion, Bchl-, prior to the formation of Bph-. This is surprising, because in the crystal structure of the Rhodopseudomonas viridis reaction center [Deisenhofer, J., Epp, O., Miki, K., Huber, R., & Michel, H. (1984) J. Mol. Biol. 180, 385-398] a Bchl is located approximately in between P and the Bph. It is possible that Bchl- (or Bchl+) is formed but, due to kinetic or thermodynamic constraints, is never present at a sufficient concentration for us to observe. Alternatively, a virtual charge-transfer state, such as P+Bchl-Bph or PBchl+Bph-, could serve to lower the energy barrier for direct electron transfer between P* and the Bph.

Bacteriochlorophylls↗
PubMed1985

Serum immunoreactive trypsin and pancreatic lipase in cystic fibrosis.

Serum immunoreactive trypsin (IRT) and pancreatic lipase have been measured in 59 patients with cystic fibrosis (age 1 month-27 years). Follow-up values were obtained from 49 patients. Their serum enzyme levels were compared to those of 120 healthy children of all age groups. Faecal fat excretion was determined in selected patients (n = 23) to elucidate the relationship between serum enzyme levels and pancreatic exocrine function. In cystic fibrosis IRT and lipase showed a very similar age-correlated pattern: in infancy levels were markedly elevated. During the following years the concentrations of both enzymes decreased rapidly and were found to be far below the normal range after the 10th year of life. Elevated enzyme levels in infancy as well as low levels in all age groups coincided with steatorrhea. Older patients (11-27 years) without severe pancreatic insufficiency however, had IRT and lipase levels in or above the normal range. In healthy children there was no age dependency of IRT levels, whereas in the first 12 months of life lipase levels were significantly lower than in later childhood.

Adolescent↗
PubMed1985

Cimetidine pharmacokinetics and dosage requirements in children.

The pharmacokinetics of cimetidine (10 mg/kg) were investigated in 11 children following an oral dose and in 9 children following an intravenous dose. The children ranged in age from 4-13 years and were undergoing radiology for upper gastrointestinal tract pain. Compared with a group of adults, the children had a higher total body clearance (11.6 +/- 3.4 versus 7.0 +/- 2.5 ml/min per kg; P less than 0.005), a larger apparent volume of distribution (1.24 +/- 0.40 versus 0.80 +/- 0.24 l/kg; P less than 0.005) and a shorter elimination half-life (83 +/- 26 versus 122 +/- 16 min; P less than 0.001) of cimetidine. Renal clearance in children comprised 70% of total body clearance, more than double that of adults (9.0 +/- 1.9 versus 4.2 +/- 2.1 ml/min per kg; P less than 0.001). The area under the cimetidine plasma concentration: time curve after the oral dose was on average 42% in children compared with adults. The mechanism for the increased elimination of cimetidine in children is suggested to be an increase in the renal tubular secretory transport of cimetidine in the kidney. A statistically significant negative correlation was observed between age and cimetidine renal clearance. A cimetidine dosage regimen of approximately 30 mg/kg per day in three to four divided doses would be an appropriate dose in children.

Administration, Oral↗
PubMed1985

Prognosis for babies born with fused eyelids.

The overall mortality for babies referred to our unit with fused eyelids was 68.7%; but when severe skin bruising was present only one of 18 babies survived (5.6%). This compares with a survival rate of 75% for those not bruised at or soon after birth. Skin bruising invariably indicates a very poor prognosis in babies born with fused eyelids.

Contusions↗
PubMed1985

Large-scale reductions in speeding and accidents in Canada and Israel: a behavioral ecological perspective.

We assessed the effects of posted feedback and warning ticket programs on speeding and accidents in two cities. In Experiment 1, speeding feedback signs were effective even when 10 were used in Dartmouth, Nova Scotia, and reductions in speeding were associated with reductions in accidents. The effectiveness of the signs was correlated with the number of intersections and residences within 0.5 km beyond them, and the signs had no effect on untreated streets. In Experiment 2, posted feedback and a warning program reduced speeding and accidents on 14 streets in Haifa, Israel.

Accidents, Traffic↗
PubMed1985

[Suture technics for the abdominal wall after midline laparotomy].

During the last 10 years 268 laparotomies by a midline incision were performed. A high incidence of seromas, fistulas caused by suturing material and wound ruptures were observed. After finding only a small number of publications in the veterinary medicine about wound healing disturbances an analysis of the human medical literature was done. This induced the change of our surgical procedure and suturing technique: The midline incision and surgical management during the laparotomies in 14 horses suffering from colic were performed by a minimized trauma. The abdominal wall was closed layer by layer in the following manner: peritoneum by a running suture of catgut metric 5, linea alba by Sultan single sutures of polyglycolic acid material metric 5 (12 cases) or of polydioxanone metric 4 (2 cases), subcutaneous layer by a running suture of polyglycolic acid material metric 4, skin by single sutures of monofilamentous synthetic material metric 2. Thus, no complications in wound healing were observed in these 14 horses. Therefore, we recommend to prove the described surgical and suturing procedure by a larger number of horses undergoing a laparotomy by a midline incision.

Animals↗
PubMed1979

Spermine-DNA complexes build up metastable structures. Small-angle X-ray scattering and circular dichroism studies.

Spermine-DNA complexes have been examined by small-angle and wide-angle X-ray scattering as well as by circular dichroism studies. Condensed complexes are building up below a critical ionic strength. We have found that at one and the same ionic strength condensed complexes having two different supramolecular structures (Type I and Type II) can coexist. The structure of the condensates depends on the method of condensate formation. Phase transitions between these structures can be induced by thermal treatment. We conclude from these facts that with polyamine-DNA condensates metastable structures are of importance.

Animals↗
PubMed1979

Adenylate cyclase in human gastric mucosa: its activation by histamine in morphologically different biopsy specimens.

In morphologically different biopsy specimens from fundic, antral and duodenal mucosa of 134 persons, basal and histamine stimulated adenylate cyclase activity was studied: Basal and stimulated adenylate cyclase activities were log-normally distributed. Only in the fundic but not in the antral and duodenal mucosa adenylate cyclase was sensitive to histamine. The mean basal activity in the fundic gastric mucosa was 148, in response to 10(-5) mol/l histamine 292 pmol cAMP/mg protein/20 min. In human fundic biopsy specimens histologically identified as normal gastric mucosa, the stimulatory effect of histamine on adenylate cyclase decreased with the individual's age. In bioptic material from patients suffering from histologically proven chronic gastritis the histamine effect decreased with the degree of atrophy. A similar loss of histamine sensitivity was found in gastric mucosal biopsies of antrectomized individuals operated at least 5 years before by the Billroth I or II method, whereas in the mucosa of patients with gastric or duodenal ulcer no loss occurred. In contrast, the most pronounced stimulatory action of histamine was found in this latter group. Since a histamine sensitive adenylate cyclase is localized only in the glandular area of the fundic mucosa and the histamine sensitivity depends on a morphological intact structure of the mucosa, it can be concluded, that the effects of histamine on adenylate cyclase and on hydrochloric acid acid secretion have to be considered as a mechanism linked together.

Adenylyl Cyclases↗
PubMed1979

Pentagastrin activation of adenylate cyclase in human gastric biopsy specimens.

Adenylate cyclase activity of human fundic mucosa is log-normally distributed and equally stimulated by pentagastrin and histamine. Cimetidine inhibits the histamine, but not the pentagastrin effect, which is even intensified by H2-receptor blockade. The results indicate that pentagastrin and histamine activate adenylate cyclase via distinct receptors.

Adenylyl Cyclases↗
PubMed1979

[The Göttinger minipig as a laboratory animal. 5. Communication: cardiac output, its regional distribution and organ blood flow (author's transl)].

In 16 juvenile minipigs weighing 3.08 kg an average cardiac output of 23 ml/100 g body weight was measured with the dye-dilution method. The microsphere technique was used to assess distribution of cardiac output and organ blood flow. In 12 adult minipigs with a mean body weight of 21.5 kg the cardiac output of 14 ml/100 g body weight was measured with an electromagnetic flowmeter. The values of total systemic and organic blood flow correlated well with those of man and partly with those of other laboratory animals.

Animals↗