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Biomedical subjects

G Lubec

Publications and source records attributed to G Lubec.

At least 253 records · Page 14Linked to original sources
PubMed1982

[Thyroid function in healthy premature infants and in premature infants with the hyaline membrane syndrome ].

The serum concentrations of thyrotropin (TSH), thyroxine (T4), trijodothyronine (T3) and of 3,3',5', trijodothyronine (reverse T3, rT3) were followed up during the first 4 weeks of life in 5 healthy premature infants and in 6 premature infants with hyaline membrane syndrome and artificial ventilation. TSH and T4 concentrations remained unchanged in both groups. T3 levels increased during the observation period and were significantly lower in the sick prematures on days 1 and 3 (p less than 0,02). T3 and the rT3/T3 ratio was increased in healthy and in the sick prematures, the sick prematures showing higher values, and decreased in both groups during the first week of life. We found no significant correlation between TSH and the peripheral thyroid hormone levels as well as no relation between the respiratory compliance-indicating degree of lung maturity-and the T3 or T4 concentrations. Postpartal T3 or T4 serum levels were correlated significantly with the duration of artificial ventilation. Our data indicate that a "low T3 syndrome" was present in all prematures after birth and that respiratory distress syndrome increased conversion of T4 to rT3. From our results we cannot conclude that substitution therapy with thyroid hormones may be useful in premature infants with the hyaline membrane syndrome.

Humans↗
PubMed1982

Glycosylation of glomerular basement membrane in Type 1 (insulin-dependent) diabetic children.

Immunoelectrophoresis of glomerular basement membrane antigens in the urine of 20 Type 1 (insulin-dependent) diabetic and 10 healthy children was performed. In 10 of the diabetic children, there was altered alpha-1-mobility, while the other diabetic and normal children showed alpha-2-mobility. After incubation with glucose, glomerular basement membrane antigens in the urine of healthy children showed alpha-1-mobility. Isolated human kidney glomerular basement membrane split products obtained by proteolytic degradation (papain, trypsin, chymotrypsin) were also investigated by immunoelectrophoresis. A difference was observed in the immunoelectrophoretic pattern of native and glycosylated glomerular basement membrane split products. A distinct increase of thiobarbituric acid assay positive glomerular basement membrane structures after incubation with glucose provides suggestive evidence for the occurrence of non-enzymatic glycosylation of glomerular basement membrane proteins. Glycosylated glomerular basement membrane proteins may contribute to both functional and morphological changes in diabetic glomerulosclerosis.

Adolescent↗
PubMed1982

Intracellular phenylalanine and tyrosine concentration in homozygotes and heterozygotes for phenylketonuria (PKU) and hyperphenylalaninemia compared with normals.

Assuming adequate technique, determinations of intracellular phenylalanine and tyrosine concentrations in lymphocytes are very reproducible. The concentrations found in this study (1981) in five homozygotes and five obligate heterozygotes for PKU and seven normals, are identical with the corresponding concentrations found in 1979 in 13 homo- and 19 obligate heterozygotes for PKU and 26 normals. The intracellular concentrations in six homo- and five heterozygotes for hyper-Phe, as determined in the present study, are intermediate between the concentrations found in PKUs and normals in the present and the former study. As in PKUs, there is no difference between homo- and heterozygotes for hyper-Phe. The hypothesis of an intracellular threshold concentration for phenylalanine triggering the production of a toxic metabolite, could explain the severe brain damage observed in untreated PKU-homozygotes, the slight damage in well-treated PKU-homozygotes and in PKU-heterozygotes, and the absence of damage in hyper-Phe homozygotes (and heterozygotes). Also the difference in brain function between homozygotes for both conditions (PKU-treated), can be understood in spite of comparably elevated extracellular phenylalanine concentrations in young patients.

Adult↗
PubMed1982

Disappearance of bowel gas in newborn infants on mechanical ventilation.

Loss of bowel gas was observed in 18 out of 49 neonates on mechanical ventilation (37%). Its occurrence was correlated to the outcome and to the use of sedative or neuromuscular paralysing drugs. None of the babies had gastrointestinal disorders requiring surgical intervention. A gasless abdomen was found in 6 our of 26 surviving neonates (23%) and in 12 out of 23 neonates (52%) not surviving the respiratory illness. Absence of intestinal gas in unsedated or unparalysed babies (23%) as well as in Alodan treated babies (19%) was found with nearly equal frequency whereas its occurrence after neuromuscular paralysation with Alloferin was significantly higher (91%). Disappearance of intestinal gas pattern despite, normal gastrointestinal patency, occurring in mechanically ventilated neonates severely affected by respiratory distress of varying origin of after neuromuscular drug paralysation should be recognized.

Gases↗
PubMed1982

Reduced collagenolytic activity of rat kidneys with steptozotocin diabetes.

Collagenolytic activity of rat kidneys with streptozotocin diabetes was estimated by means of a biological collagenase assay and compared to healthy controls. Collagenolytic activity was found significantly decreased in rat kidneys with diabetes correlating with blood glucose levels (r = -0.82, p less than 0.001). Elevated blood glucose levels seem to be responsible for the inhibition. This is supported by our experiment of incubating bacterial collagenase with several carbohydrates as glucose, galactose and saccharose: glucose and galactose significantly inhibited the collagenolytic activity, while saccharose failed to inhibit the enzymatic reaction. The interpretation of the results is that glucose is able to bind to the enzyme as Schiff base, which could be shown by tritiated sodium borohydride reduction of the Schiff base formed between collagenase and glucose. Another support of the hypothesis is that blocking of the amino group of lysine at the active site either by glucose or trifluoroacetylation of collagenase is reducing the collagenolytic activity. The biological significance could be the decreased catabolism of collageneous material of the extracellular matrix, as, e.g., the glomerular basement membrane, which was reported in a previous publication.

Animals↗
PubMed1982

Respiratory compliance of newborns after birth and its prognostic value for the course and outcome of respiratory disease.

The compliance of the respiratory system was determined at an average of 2.89 h (range 45 min - 8 h) after birth in 82 newborns who were retrospectively divided into group 1: healthy newborns (mean gestational age 37.1 weeks, range 30 - 41 weeks); group 2: newborns with respiratory distress (RD) needing no ventilatory support (mean gestational age 37.3 weeks, range 35--40 weeks); group 3: newborns with RD needing ventilatory support and surviving (mean gestational age 34.3 weeks, range 30--39 weeks), and group 4: newborns with RD who needed ventilatory support and died (mean gestational age 30.8 weeks, range 28--37 weeks). Respiratory compliance was measured by the airway occlusion technique in spontaneously breathing babies and by injecting a known volume of gas into the closed airway system and measuring airway pressure in intubated babies. The difference in postnatal compliance was statistically significant (p less than 0.01) in those four groups and was correlated with the severity of the disease in groups 2 and 3. In infants with RD, compliance was highly predictive for the need for ventilatory support (93% correct and 7% erroneous) and in infants with ventilatory support, for the mortality (83% correct and 17% erroneous). We conclude that postnatal compliance measurements are very useful to predict the course and outcome as well as to classify the severity of RD.

Gestational Age↗
PubMed1982

[Reduced susceptibility of nonenzymatically glucosylated peptides against proteolytic cleavage (author's transl)].

Two peptides, alpha-endorphin and beta-melanocyte stimulating hormone, were nonenzymatically glucosylated, degraded by several proteolytic enzymes and the susceptibility against proteolytic enzymes compared to the peptides in the native, nonglucosylated state. Glucosylation was controlled by thin layer chromatography revealing Rf differences between the native and glucosylated peptides. Quantitative estimation of peptides was performed applying high performance liquid chromatography. The results showed reduced susceptibility of nonenzymatically glucosylated peptides to the proteolytic enzymes (papain, chymotrypsin, trypsin and papain) applied.

Chromatography, Thin Layer↗
PubMed1982

Reduced susceptibility of glycosylated hemoglobin to proteolytic cleavage.

Four different experimental designs were selected to study, whether glycosylation of hemoglobin alters susceptibility against proteolytic degradation. We compared the resistance of different hemoglobin fractions against degradation by pure proteolytic enzymes, by liver cell culture, by live organ culture and the resistance of in vitro glycosylated vs. "non-glycosylated" hemoglobin solutions. The hemolysates were characterized by high performance liquid chromatography. The degree of glycosylation of hemoglobin was further estimated by the thiobarbituric-acid assay. From the data presented it is concluded, that the glucose moiety linked to the N-terminal valine and lysine residues of the alpha- and beta chain of the hemoglobin exerts a protective effect against proteolytic cleavage. This could explain the extended lag phase in response of glycosylated hemoglobin to an improved metabolic control in diabetic patients and the discrepancy between the rate of synthesis and the rate of catabolism.

Animals↗
PubMed1982

[Enzyme activities of native non-enzymatically glucosylated trypsin, chymotrypsin and papain].

The proteases trypsin, alpha-chymotrypsin and papain were incubated with glucose for a period of 10 days at 37 degrees C and activity was tested in comparison to the enzymes incubated with the puffer solution only without glucose addition. Papain additionally was incubated for 10 days at 37 degrees C with the carbohydrates galactose, sucrose, lactose, glucosamine, galactosamine and mannosamine. While trypsin and chymotrypsin showed no change in enzymatic activity after incubation with glucose, the activity of papain was reduced by 70% to 90% (mean 84%). Incubation with galactose also inhibited papain activity but to a lesser extent (25% to 60%, mean 43%). Incubation with the other carbohydrates failed to inhibit papain activity. The mechanism inferred is nonenzymatic glucosylation of papain possibly as ketoamine linkage at the lysine residues situated close to the active site of papain causing steric or allosteric hindrance of the papain activity. The serine hydrolases trypsin and chymotrypsin without lysine residues near their active sites revealed unchanged activity after incubation with glucose.

Carbohydrate Metabolism↗
PubMed1982

[Non-enzymatic glucosylation of proteins].

The modification of haemoglobin A by glucose to haemoglobin A Ic is a classical example for a nonenzymatic glucosylation (n. e. glu.) reaction of a protein. It has been suggested, that various proteins are subjected to this process during hyperglycemia phases, if the protein meets certain steric, electrostatic and biochemical characteristics. In the present report n. e. glu. of haemoglobin, serum protein, collagen, basement membrane protein and alkaline phosphatase is discussed. It is suggested that n. e. glu. might influence protein function and forms thus the biochemical basis for specific complications of diabetes mellitus in an outside pregnancy.

Adolescent↗
PubMed1982

[Glycosaminoglycan-glomerular basement membrane interactions revealed by affinity chromatography (author's transl)].

Glycosaminoglycans (GAG) are major constituents of the extracellular matrix of the kidney and an integral part of the glomerular basement membrane (GBM). To elucidate the nature of the interaction between these structures we performed binding studies applying affinity chromatography. Solubilized glomerular basement membranes were coupled to the gel and the binding of heparan sulfate (HS), heparin (H), chondroitin-4-sulfate (Ch-4-S) and hyaluronic acid (HA) was studied, HS and H bound strongly to the glomerular basement membrane eluting with 4 M urea and 3 M NaCl on contrary to chondroitin-4-sulfate and hyaluronic acid which did not bind in our system. In order to determine which component of the GBM is responsible for the binding of the GAG we studied the linkage between basement membrane collagen type IV and laminin with the GAG. Both substances reflected the binding activity of their matrix substance for HS and H, but presenting low binding affinity for Ch-4-S reversible with 4 M urea and 1 M NaCl. The binding of the highly charged GAG could play an important role in physiological and pathophysiological functions with special regard to glomerular filtration processes.

Basement Membrane↗
PubMed1981

[Congenital toxoplasmosis in two newborn infants (author's transl)].

Two newborn infants with congenital toxoplasmosis despite serological testing during pregnancy were observed at our premature and neonatal intensive care unit within a short time of one another. In one case the counter-regulatory late first test, performed only in the 26th week, was positive with a high titre. The immediately recommended treatment was not carried out. Apart from the signs of congenital generalized infection, the newborn infant already manifested chorioretinitis and encephalitis. In the second case the initially serologically-negative pregnant women became infected only during the 35th to 36th week of gestation, around the time of the third serological examination. The child was born with slight signs of general infection, but without CNS involvement. Immediate postnatal treatment resulted in complete cure. This shows that such rare cases which can no longer be detected by serological testing can be treated postnatally with good results.

Adult↗
PubMed1981

[Is the airway-occlusion-technique used in respiratory physiology hazardous for the newborn infant? (author's transl)].

The effect of the airway-occlusion-technique (AOT) on the cardiac- and respiratory frequency, respiratory compliance and pO2 was studied in 5 healthy and 7 cardio-respiratory ill newborns. During a mean study duration of 10.8 minutes (11 occlusions) none of the variables mentioned changed significantly. We conclude that the non-invasive AOT, which informs about lung mechanics and respiratory control, carries no risk for the newborn infant.

Elasticity↗
PubMed1981

[Linear epidermal nevus with multiple malformations. (author's transl)].

We report about a 12 year old boy who was born with a linear epidermal nevus. This nevus extended from the umbilicus strictly along the midline to the symphysis and continued on the right leg caudally to the medial brim of the foot and the first and second toe. Changes of bone structure are seen at-x-ray examination of the right hip and leg. Vascular dysplasia with arteriovenous shunts and spinal angiomas were found by angiography in the vascular bed of the left iliac artery. The length of the legs differed due to hyperplasia of the left lower extremity and both feet resembled the "Friedreich-foot".

Abnormalities, Multiple↗