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W Albers

Publications and source records attributed to W Albers.

18 recordsLinked to original sources
PubMed1993

Pre-steady-state charge translocation in NaK-ATPase from eel electric organ.

Time-resolved measurements of charge translocation and phosphorylation kinetics during the pre-steady state of the NaK-ATPase reaction cycle are presented. NaK-ATPase-containing microsomes prepared from the electric organ of Electrophorus electricus were adsorbed to planar lipid bilayers for investigation of charge translocation, while rapid acid quenching was used to study the concomitant enzymatic partial reactions involved in phosphoenzyme formation. To facilitate comparison of these data, conditions were standardized with respect to pH (6.2), ionic composition, and temperature (24 degrees C). The different phases of the current generated by the enzyme are analyzed under various conditions and compared with the kinetics of phosphoenzyme formation. The slowest time constant (tau 3(-1) approximately 8 s-1) is related to the influence of the capacitive coupling of the adsorbed membrane fragments on the electrical signal. The relaxation time associated with the decaying phase of the electrical signal (tau 2(-1) = 10-70 s-1) depends on ATP and caged ATP concentration. It is assigned to the ATP and caged ATP binding and exchange reaction. A kinetic model is proposed that explains the behavior of the relaxation time at different ATP and caged ATP concentrations. Control measurements with the rapid mixing technique confirm this assignment. The rising phase of the electrical signal was analyzed with a kinetic model based on a condensed Albers-Post cycle. Together with kinetic information obtained from rapid mixing studies, the analysis suggests that electroneutral ATP release, ATP and caged ATP binding, and exchange and phosphorylation are followed by a fast electrogenic E1P-->E2P transition. At 24 degrees C and pH 6.2, the rate constant for the E1P-->E2P transition in NaK-ATPase from eel electric organ is > or = 1,000 s-1.

Animals↗
PubMed1992

The production of fatty acid modifying enzyme (FAME) and lipase by various staphylococcal species.

Eighty-six strains encompassing 11 species of coagulase-negative staphylococci were examined for the production of fatty acid modifying enzyme (FAME) and lipase. Staphylococcus schleiferi and S. saprophyticus most closely resembled S. aureus in that 80% of the strains produced both enzymes. In contrast, no strains of S. lugdunensis and S. haemolyticus tested produced these enzymes. S. simulans was unusual in that eight of 10 strains produced FAME, but only one produced lipase. Among the other species the proportion of strains producing both enzymes ranged from 10 to 60%. Generally there was a strong correlation between FAME and lipase production.

Acyltransferases↗
PubMed1990

Design methods for some dose-response models.

A recently described design method for one-parameter biomedical models such as limiting or serial dilution assays is generalized to two-parameter models for which the dose-response relationship can be expressed as a linear regression model with parameters alpha (intercept) and beta (slope). Design formulae are proposed for three different cases in which prior information about the unknown regression parameters alpha and beta is available (alpha known, beta known and neither known, respectively). A suitable transformation of the two-parameter model enables the direct application of the one-parameter design method to the first two cases, while the third needs more advanced considerations. Two experimental designs, taken from the literature, are reproduced as closely as possible using the methods described, thus showing under which circumstances these designs are suitable.

Animals↗
PubMed1988

Using jackknife methods for estimating the parameter in dilution series.

Dilution assays are quantal dose-response assays that detect a positive or negative response in each individual culture within groups of replicate cultures that vary in the dose of cells/organisms tested. We propose three jackknife versions of the maximum likelihood estimator of the unknown parameter, i.e., the frequency of a well-defined cell within the context of limiting dilution assays or the density of organisms within the context of serial dilution assays. The methods have been evaluated with artificial data from extensive Monte Carlo experiments. As a result of these experiments and theoretical considerations, the jackknife version based on deleting one individual culture at a time is proposed as the statistical procedure of choice. The next best method is the jackknife version based on leaving out the same replicate from each of the culture groups at a time.

Biometry↗
PubMed1986

[Surgical treatment of recurrent ventral dislocation of the shoulder using the Weber rotation osteotomy].

There are different procedures for surgical treatment of a recidivating ventral dislocation of the shoulder. In our hospital the rotatory osteotomy according to Weber proved good; in accordance with the findings it can be combined with other procedures. The surgical procedures and our results are explained. In our opinion, this surgical treatment will effect, besides known results (rotation of head defect to lateral), an essential stabilisation of the joint, by means of strain exercised on M. infraspinatus and the upper part of M. teres minor.

Adolescent↗
PubMed1985

[Surgical treatment of osteochondrosis dissecans of the knee joint].

There are numerous methods for surgical treatment of osteochondrosis dissecans of the knee. These methods and their indications are pointed out. In our clinic screw-fixation of dissecates respectively of osteocartilaginous grafts proved good. Surgical procedure, after-treatment and results are reported.

Adolescent↗
PubMed1985

[Spontaneous femoral condyle necrosis of the knee joint (Ahlbäck disease)].

The aetiology of Morbus Ahlbäck (spontaneous osteonecrosis of the femoral condyles of the knee joint) is still unknown. Sudden onset of pain characterises the beginning of complaints. Only scintimetry results in early diagnosis. Larger osteonecroses are to be treated surgically, for example by osteotomy. In extensive osteonecroses we prefer alloarthroplastic replacement (mostly unicondylar).

Aged↗
PubMed1984

[Treatment of tuberculosis of the wrist. 89 long-term course studies and presentation of the current therapeutic concept].

The decrease in the incidence of tuberculosis may today readily result in a lack of attention being paid to the extrapulmonary forms of this disease in the differential diagnosis of bone changes. Today massive joint destruction can be prevented with the aid of anti-tuberculous chemotherapy, the early establishment of the diagnosis (for example arthrotomy) and surgical intervention (synovectomy or excision of focus, osteosynthesis). On the basis of our patients treated between 1947 and 1982 we describe the diagnostic and therapeutic procedures followed over the last decades. The results are discussed. Our present therapeutic concept is explained.

Adolescent↗
PubMed1982

[Problems in the evaluation of results following reconstruction of peripheral nerves from the viewpoint of the clinician and the patient].

Between 1969 and 1977 in a total of 395 patients severed peripheral nerves were reconstructed by microsurgical technique. In 30% of cases primary repair was carried out, in 22% secondary reconstruction, and in 48% a free transplantation. The least favorable results occurred after secondary reconstruction of sensory nerves; the best after direct suturing without tension. Comprehensive consideration of the results is not helpful in terms of prognosis. Statistics for special groups have to be established taking into consideration the preoperative findings, the situation of the patient, and the type of postoperative treatment.

Adolescent↗
PubMed1982

[Tendon sutures with a new monofilament synthetic absorbable suture material (PDS-suture of 6-0 strength). Results of animal experiments].

The absorbable synthetic suture (PDS suture 6-0 with spatula needle) was examined by experiments on the tendon of the M. flexor digitorum pedis communis of the hare. A total of 34 tendon sutures was prepared histologically and evaluated. The new suture material is distinguished by greatly extended absorption time, low foreign body reaction and an improved tensile strength. With this suture, the conditions in which absorbable suture material can be used are increased. This is particularly true of so-called bradytrophic tissue.

Animals↗
PubMed1981

[Transplantation of nervus peroneus by microsurgery (author's transl)].

From 1969-1977 at the Erlangen University Surgical Clinic 15 transplantations of the nervus peroneus were performed. 10 patients could be followed up within a time of 2-5 years after operation. As to the sensibility in most cases only protective sensibility could be achieved; as to the motor function the results were likewise poorer than in the upper limb. Beside our own results those of other authors were reported. Possible causes of the relatively bad prognosis of the Nervus peroneus were shown.

Accidents↗
PubMed1981

[The operative treatment of epidermolysis bullosa hereditaria (author's transl)].

After demonstrating four clinical patterns of epidermolysis bullosa hereditaria the operative procedure will be discussed in two cases. One is a now 16-year-old male, the other a 18-year-old girl, who suffer from this disease. While removing the affected skin in a first operation, the defect is covered by a split skin graft taken from a non-affected area. In a second operation or in repeated operative procedures, not only must the affected skin be removed but also any existing scars and contractures. Children who suffer from this form of epidermolysis bullosa hereditaria present a severe problem. For all who deal with this problem, the painstaking preoperative preparation as well as the choice of the most suitable anaesthetic are as important in every respect as the operation itself and the postoperative and psychosocial care.

Adolescent↗
PubMed1977

A-V block.

Explore the source record for details and available documents.

Atrioventricular Node↗
PubMed1975

Sodium + potassium-activated ATPase of mammalian brain. Regulation of phosphatase activity.

1. The K+-nitrophenylphosphatase activity associated with mammalian brain (Na+ + K+)-ATPase displays K+ activation curves that have intermediary plateaus and maxima in the presence of less than saturating concentrations of Na+. Zero Na+ and saturating Na+ produce sigmoid K+-activation curves with low and high K+ affinities respectively. 2. ATP inhibits K+-activated nitrophenylphosphatase through both competitive and non-competitive mechanisms. ATP is synergistic with Na+ in the mechanism which converts the enzyme from low to high K+ affinity. 3. The Na+ and K+ interactions can be accounted for by equations which describe a model with separate regulatory sites for Na+ and K+ and with K+- requiring catalytic site which is only accessible in one of the two principal conformational stages of the enzyme. 4. The effects of ATP can be accounted for by the same model through interactions at a single nucleotide binding site. Inhibition which is competitive with K+ and non-competitive with substrate arises from stabilization of the inactive enzyme conformation. Inhibition which is non-competitive with K+ and competitive with substrate results from interactions with the active enzyme conformation. The synergism between Na+ and ATP appears to arise as a consequence of the formation of phosphoryl enzyme. 5. A model for (Na+ + K+)-ATPase is discussed which involves in-phase coupling of subunit interactions as suggested by these studies.

Adenosine Diphosphate↗