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Biomedical subjects

M Hahn

Publications and source records attributed to M Hahn.

At least 253 records · Page 14Linked to original sources
PubMed1985

Repeated sequences similar to insertion elements clustered around the nif region of the Rhizobium japonicum genome.

Two different repeated sequences (RSs) were discovered in the Rhizobium japonicum genome: RSRj alpha is 1126 base pairs long and is repeated 12 times; RSRj beta is approximately 950 base pairs long and is repeated at least 6 times. Their arrangement in root nodule bacteroid DNA is the same as in DNA from bacteria grown in culture. Deletion analysis showed that many copies of alpha and beta are clustered around the nitrogenase genes nifDK and nifH, or, in general, they are found within a genomic region harboring genes that are nonessential for growth. One copy each of alpha and beta are located upstream of nifDK and are adjacent to each other. Neither of them, however, is involved in the expression of nifDK. Nucleotide sequence analysis of three copies of RS alpha revealed many characteristics of procaryotic insertion sequence elements: potential inverted repeats at their ends, potential target site duplication, and large open reading frames. Despite this, their genomic positions appear to be stable. One possible function of these RSs is in deletion formation probably via recombination between them.

DNA Transposable Elements↗
PubMed1985

[Ambulatory operative treatment of fresh fibular ligament ruptures].

Sudden accidental supination of the foot often causes the fibular ligament to be ruptured which is mostly mistaken for a sprained ankle and treated conservatively. From May 1977 to February 1984 we treated 431 cases of this kind surgically by suture of the ruptured ligament. Also in children suture of the ligament is indicated. The operation can be performed as an outpatient procedure.

Adolescent↗
PubMed1984

Three-dimensional reconstruction of imperfect two-dimensional crystals.

An outline is given of the general methodology of 3D reconstruction on the basis of correlation averages of the 2D projections: this hybrid real space/Fourier space approach substantially alleviates one of the most serious limitations on obtaining high resolution 3D structures, namely crystal distortions. The paper discusses some of the technical problems involved, namely optimisation of tilt increments, a posteriori tilt angle determination, extraction of lattice line data from averaged unit cells, and stain/protein boundary determination. The approach is illustrated by application to a 2D crystal from a bacterial cell envelope.

Bacteria↗
PubMed1984

[Ileus in the aged].

From 1973 to June 1982, 218 patients older than 70 years (148 women, 70 men) suffering from acute bowel obstruction were seen at our Dept. The mortality rate came up to 33%. Main causes of the ileus were incarcerated hernias and colonic obstruction (25% each). In case of an incarcerated hernia the authors emphasize early operation and colostomy in case of colonic obstruction due to tumour stenosis.

Aged↗
PubMed1984

[Fractures of the tarsus and metatarus in children--diagnosis, treatment, results].

Within 4 years (September 1977 to September 1981) 169 closed fractures of the feet were seen at our paediatric-surgical outpatient dept. Special therapeutic problems arose only in fractures of the talus and the calcaneus, although necrosis of the talus were rare. Concerning treatment a plaster cast, sufficient relief and early arch-support are essential. Fractures of the other tarsal bones were mostly without problems, a conservative treatment was used for these cases.

Adolescent↗
PubMed1982

Effect of brain growth stages on T-maze acquisition in mice.

Recently, it has been shown that brain growth is characterized by periods of especially large increases in growth, with "plateaus" in growth between these "spurt" periods. In humans, these spurts in brain growth are correlated with spurts in mind growth, collectively termed phrenoblysis. Brain growth spurts in rodents occur at 0-6, 8-12, and 17-23 days of age with plateaus in-between. We examined two questions. First, are there differences in learning ability associated with spurts and plateaus in brain growth? Second, can learning during these stages be altered through genetic and environmental manipulations? We employed the high and low lines of the Fuller brain weight selection mice, which are known to have different developmental patterns, and early handling procedures, known to alter growth rates. The results showed that animals tested during a proposed brain growth spurt were superior to animals tested during a brain growth plateau in learning a shock-escape T-maze.

Age Factors↗