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Biomedical subjects

M Becker

Publications and source records attributed to M Becker.

At least 307 records · Page 17Linked to original sources
PubMed1986

Solid-phase extraction of acetazolamide from biological fluids and subsequent analysis by high-performance liquid chromatography.

A sensitive, relatively fast and simple to operate high-performance liquid chromatographic method for the determination of acetazolamide in plasma and saliva is described. Quantitative extraction of the drug from both plasma and saliva was achieved using commercially available reversed-phase octadecylsilane-bonded silica column (Bond-Elut C18, 2.8 ml capacity). Acetazolamide and the internal standard are retained on the Bond-Elut C18 column and reproducibly recovered by elution with methanol. Liquid-liquid partition chromatography, carried out on a 30-cm mu Porasil column (10-microns porous silica) using a mobile phase consisting of dichloromethane-ethanol-water-glacial acetic acid (500:65:65:1), provided adequate separation with acceptable retention times. Acetazolamide levels in the region 50-100 ng/ml can be determined in 100 microliters of plasma or 200 microliters of saliva employing ultraviolet detection at 254 nm with a sensitivity of 0.005 absorbance units full scale. Although the method is primarily used to determine steady-state drug levels in paediatric patients, its general applicability is illustrated by the 24-h plasma and saliva concentration profiles obtained from a male volunteer following oral administration of acetazolamide.

Acetazolamide↗
PubMed1986

The histocompatibility of a new bovine pericard graft.

An artificial defect of the umbilical area in ten calves was covered by a pericard graft whose new preparation method has been proved in bovine vessel grafts. Between 2 and 6 months postoperatively (p.o.) two animals at a time were euthanized to sample the graft and its surrounding tissue for histological investigations. On the one hand, there was an inflammatory foreign body type granulomatous reaction, but on the other hand this did not lead to rejection. Within the 6-month observation time the graft fibers were immigrated by the own young collagen fibers. We interpret this as a guide function of the graft fibers. Tiny focal calcifications appeared to be the effect of an intensive tissue irritation which may be caused by an incomplete edulcoration of the chemical substances used during preparation. We recommend a longer edulcoration time to prevent these reactions.

Animals↗
PubMed1986

Biliary cholesterol saturation in non-obese women and non-obese men before and after puberty.

The lipid composition of gallbladder bile was determined in forty-seven normal, non-obese subjects (twenty females and twenty-seven males) without gallstones ranging in age from seven months to twenty-nine years. Before puberty, bile was undersaturated with cholesterol in both sexes to the same extent. After puberty a marked increase in cholesterol saturation was observed in females but not in males (138% vs 88%; P less than 0.01). A significant correlation between age and cholesterol saturation could be observed in females (r = 0.546; P less than 0.05) but not in males. In addition a significant correlation between absolute weight and cholesterol saturation in all females (r = 0.827; P less than 0.001) and those after puberty (r = 0.659; P less than 0.05) could be demonstrated. In neither sex was saturation related to body mass index or ideal body weight. These findings suggest that saturation of bile raises in women during puberty but not in men, and this sex-related difference in cholesterol saturation probably contributes to the more common occurrence of gallstones in women than in men.

Adolescent↗
PubMed1986

[Circulating somatostatin concentrations in childhood. Studies in normal weight and obese children and patients with growth hormone deficiency].

At present in childhood there is only few information about the importance concerning circulating somatostatin concentrations. We therefore investigated the plasma somatostatin response to a mixed meal, an oral glucose load, pentagastrin injection and insulin hypoglycemia in normal weight and obese children and patients with growth hormone deficiency. Results in normal weight children: 1. Following a 800 kcal mixed meal (50% carbohydrate, 35% protein, 15% fet) peak values of plasma somatostatin were reached within 30-180 min (37.6 +/- 4.2 pg/ml vs. 58.5 +/- 3.4 pg/ml; p less than 0.05) in 6 children. 2. In response to oral glucose load of 1.75 g/kg bw glucose no alterations of plasma somatostatin levels were observed in 13 children 3. Injection of 6 micrograms/kg bw pentagastrin s.c. in 10 children resulted in maximal increase of somatostatin concentrations between 5 and 15 min (32.0 +/- 4.5 pg/ml vs. 69.1 +/- 7.4 pg/ml; p less than 0.01). 4. Injection of 0.1 IU/kg bw insulin in 7 children induced hypoglycemia and stimulated peak values of plasma somatostatin within 15-60 min (32.0 +/- 6.6 pg/ml vs. 57.4 +/- 6.4 pg/ml; p less than 0.01). - Results in obese children: Following mixed meal ingestion in 7 obese children plasma somatostatin response was comparable to controls. Although integrated insulin response over 180 min was higher in this group (9694 +/- 1363 microU/ml vs. 5054 +/- 651 microU/ml; p less than 0.05) the integrated somatostatin response (9038 +/- 1852 pg/ml) did not differ from controls (8614 +/- 876 pg/ml). After oral glucose load no changes in circulating somatostatin concentrations were observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
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↗
PubMed1984

Biliary lipid metabolism in children with chronic intrahepatic cholestasis.

Biliary lipid composition, standard liver function tests, serum lipids and faecal fat excretion were studied in 15 children with chronic intrahepatic cholestasis (severe intrahepatic cholestasis, n = 6; paucity of intralobular bile ducts, n = 4; benign recurrent cholestasis, n = 5) and compared to 15 children without gastrointestinal diseases. Severe and benign intrahepatic cholestasis were associated with normal or moderately elevated serum lipids. Biliary lipid concentrations were extremely reduced, bile acid concentrations were below the critical micellar concentration. This may account for the high incidence of gallstone formation in these patients. Remission periods in patients with benign recurrent cholestasis were not followed by complete normalisation of biliary lipid concentrations, indicating a primary defect in hepatic excretory function. Children with paucity of intralobular bile ducts showed markedly increased serum lipids, but only a two-fold reduction in biliary lipid concentrations. Cholic acid was the predominant bile acid in bile of all cholestatic children even during remission. Neither increased levels of monohydroxy bile acids nor unusual bile acids could be identified in notable amounts.

Adolescent↗