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Biomedical subjects

R Schubert

Publications and source records attributed to R Schubert.

At least 19 recordsLinked to original sources
PubMed1992

Familial rectal pain: a type of reflex epilepsy?

We studied 2 members of a family suffering from paroxysmal attacks elicited by tactile stimuli. The attacks consist of burning pain of the stimulated body part, followed by either complete collapse or tonic posturing. Noxious stimuli provoke episodes regardless of their somatic location, whereas it is only necessary for nonnoxious stimuli to be applied to specific trigger zones, such as the rectum, to provoke attacks. Episodes are most commonly precipitated by bowel movement, leading to extreme fear of defecation and resultant fecal retention. An ictal electroencephalographic video recording revealed only slowing of the background; however, serum prolactin was significantly elevated postictally. The attacks were completely suppressed by carbamazepine and resumed on discontinuing the medication. These attacks may represent a form of reflex epilepsy manifested by autonomic nervous system dysfunction.

Adult↗
PubMed1991

First results on the incorporation and excretion of 15N from orally administered urea in lactating pony mares.

Two lactating pony mares were given oral offers of 20 g 15N urea [95 atom-% 15N-excess (15N')] on 6 subsequent days. About 80% of the consumed 15N' were excreted via urine and faeces, but only about 2% via milk. The 15N' secreted via milk-lysine only amounted to 0.04% of the 15N' intake. The recovery was about 90% in each case. Tissues with active metabolism had an unexpectedly high labelling (greater than 0.3 atom-% 15N'). The low extent of the conversion of oral urea N into milk-lysine speaks against an essential participation of the enteral synthesis in meeting the amino acid requirement of lactating mares. It was already concluded from this results that the determination of the amino acid requirement will be necessary for this group of performance.

Administration, Oral↗
PubMed1991

[The dynamics of bone apposition in different animal species--a comparative study].

The time of the bone apposition was compared in rats, rabbits and guinea pigs with the aid of enzyme-activity measurements, determination of the proportion of minerals and the judgment of the cell generation. For this intention a defect was made in the distal femur epiphyses at the three species. The animals were observed for a term of 15 weeks. The results showed little differences with regard to the speed of the bone apposition in the three called species. The bone metabolism of rats was higher than those of the other ones. A clear reference value for the enzyme activity to a define point of time of the mineralization could not be ascertained.

Alkaline Phosphatase↗
PubMed1991

[3D displays for craniofacial surgery].

3D visualisation from tomographic image sequences has turned out to be a useful addition to diagnosis and surgical planning in craniofacial surgery. However, its clinical use still suffers from the very large variety of different methods and parameters from which the surgeon may choose. This is true not only of the data acquisition but also for of documentation of the results. Furthermore, there is no standardisation of procedures according to classes of malformations. This paper presents a systematic investigation of these problems. It proposes a standardisation of craniofacial malformations and describes an optimisation of the procedure of 3D visualisation. The procedure described has become a standard tool for craniofacial surgery in our hospital.

Cleft Lip↗
PubMed1990

["Implant"--software for the documentation of statement and course in the special dentist hour consultation of implantology].

A programsystem is presented which supports the attending physician on entering symptoms of clinical and paraclinical parameters. The system runs on personal computer with Z-80 CPU under dBASE II. The program consists of six parts: 1. simple patient data, 2. oral documentation, 3. diagnostical base program, 4. sketch of therapeutics, 5. dispensaire documentation. It aims on the reduction on routine work (e. g. data in- and output) and simple statistical analysis (view of success of several implantationsystems).

Dental Implantation↗
PubMed1989

Non-leaky vesiculation of large unilamellar vesicles (LUV) induced by plasma high density lipoproteins (HDL): detection by HPLC.

Interaction of large unilamellar phosphatidylcholine vesicles (LUV, 75nm) and plasma high density lipoproteins (HDL) resulted in a non-leaky vesiculation of LUV. This vesiculation was detected by a HPLC-system consisting of a combination of three TSK-gel columns (6000PW, 5000PW, 3000SW). With increasing incubation time liposomal [14C]PC, entrapped [3H]inulin, and apoprotein of HDL origin decreased. The decrease was accompanied by a formation of new particles, consisting of liposomal PC and apoprotein. These particles also enclosed [3H]inulin, reflecting a hydrophilic inner space. The formation of the particles reached a maximum after one day of incubation. Retention time was 21 minutes for LUV, 28 minutes for the new particles, and 36 minutes for HDL. In vesicles with membranes consisting of phosphatidylcholine and 30% cholesterol no interactions were observed.

Carbon Radioisotopes↗
PubMed1989

Preparation of hemoglobin-containing liposomes using octyl glucoside and octyltetraoxyethylene.

Hemoglobin (Hb) was encapsulated in phosphatidylcholine vesicles by removal of the detergent n-octyl beta-D-glucoside (OG) or n-octyltetraoxyethylene (C8E4) out of mixed detergent-lipid micelles in Hb solution. Three types of apparatus were used for dialysis. Dialysis buffer flow rates, the surface area of the dialysis membranes, and detergent-lipid interactions determined the rate of dialysis, which influenced liposome size and lamellarity. Slow dialysis led to the formation of multilamellar liposomes, at increased dialysis rates Hb liposomes became smaller and unilamellar. Hb was enclosed at highest concentrations in larger liposomes, which included the negatively charged lipid phosphatidylserine or phosphatidic acid as a membrane component. Co-encapsulation of the allosteric factor inositol hexaphosphate led to oxygen dissociation curve values almost identical to those of whole blood. The oxygen-release capacity of Hb liposome suspensions in the physiological partial pressure range was comparable to whole blood. Storage of Hb liposomes for 2 months leaves oxygen-carrying characteristics virtually unchanged, with met-Hb levels increasing to only 11% of total Hb. Preparation of Hb liposomes by dialysis of octyl glucoside or C8E4 is a mild and efficient method for encapsulation of Hb. Since these Hb liposomes can be produced in scale-up batch sizes, they are a candidate for use as an oxygen-carrying blood surrogate.

Blood Substitutes↗
PubMed1989

The legumin gene family: structure and evolutionary implications of Vicia faba B-type genes and pseudogenes.

We have characterized several Vicia faba genes encoding methionine residue-free group B subunits of the 11S or legumin storage proteins. The respective gene subfamily consists of 10 to 15 members, six of them having been studied by DNA sequence analysis. Four functional genes (LeB2, LeB4, LeB6, LeB7) are highly homologous in their coding region and 0.3 kb of their 3' flanking sequences. On the other hand, two pseudogenes (psi LeB1, psi LeB5) have accumulated a large number of mutations including an identical 0.7 kb internal deletion; they are both flanked by a repetitive element. Analysis of sequence changes show that transitions are nearly double as frequent as transversions. CpG is the most infrequent dinucleotide whereas TpA is significantly underrepresented in exon sequences. End points of deletions are correlated with short direct repeats and preferentially found in the two introns. Our studies indicate that the Vicia faba legumin B gene subfamily contains a group of expressed, highly homologous genes as well as more diverged pseudogenes.

Amino Acid Sequence↗
PubMed1989

[Ruminal 15N-straw degradation in sacco and the in vivo digestibility of 15N from straw in the sheep and pony].

The nylon-bag method was applied for determination of the rumen degradation of dry matter and nitrogen of 15N-labelled wheat straw. For the experiment 4 wethers fitted with a rumen cannula were used. The bags containing 15N straw were introduced into the rumen and withdrawn 3, 6 or 12 h after incubation. In a second experiment the apparent 15N-digestibility of the same straw was determined in wether and pony. The dry matter disappearance varied between 6 and 23%. For 15N-labelled straw the disappearance of 15N was higher than that of total N. 12 h after incubation 71% of 15N and only 25% of total N were disappeared. It was calculated that after incubation rumen microbial-N in the nylon bag increased from 31% (3 h) to 45% (6 h) and 61% (12 h) resp. The apparent 15N digestibility amounted 53 +/- 2% for wethers and 51 +/- 2% for ponies.

Animal Feed↗
PubMed1989

The use of arginine brilliantgreen glucose peptone broth (ABGP medium) as a primary culture medium for Pseudomonas aeruginosa.

A new medium is described for the isolation of P. aeruginosa organisms which have been damaged by chlorination. This medium utilises the fact that with arginine. P. aeruginosa produces a strongly alkaline reaction resulting in an easily identified colour change from gray-green to blue-violet. The indicators used for this purpose are bromothymol blue and cresol red. The medium may be used with either the membrane filter or the liquid enrichment technique. Incubation is at 37 degrees C for 24 or 48 h.

Anti-Infective Agents, Local↗
PubMed1989

[A method for the standardized in vitro testing of biomaterials with bacterial cultures].

The preclinical investigation of potential biomaterials requires a comprehensive profile of biological parameters. In the present paper a new in vitro test will be described which allows a standardized testing of the effect of biomaterials on the proliferation of bacteria. For this test eluates of solid materials, granulates or powders of potential biomaterials were prepared. These eluates were mixed a bacterial culture containing a definite number of microbes and incubated for 4-20 hours at 37 degrees C. The effect on bacterial growth was determined photometrically.

Biocompatible Materials↗
PubMed1989

Activation and blocking effects of divalent cations on the calcium-dependent potassium channel of high conductance.

Using the patch-clamp technique the action of internal barium- and magnesium-ions on the calcium-dependent potassium channel in the membrane of vascular smooth muscle cells from the media layer of the human aorta was studied. Under symmetrical potassium conditions in excised inside-out patches bathed in the standard solution containing EGTA, the addition of barium as well as magnesium led to a concentration-dependent shift of the activation-curves to negative values of the membrane potential compared with the control, a block of single channel activity by barium, whereas no inhibitory effects by magnesium were registered. Thus, these results suggest that the process of channel activation of the calcium-dependent potassium channel of high conductance depends not merely on calcium but also on other divalent earthalkali ions.

Barium↗
PubMed1988

Structural changes in vesicle membranes and mixed micelles of various lipid compositions after binding of different bile salts.

Binding equilibria of common bile salts (BS) and different mixtures of membrane lipids were correlated with BS-induced structural changes of large unilamellar vesicles, with transition of vesicles to mixed micelles (MM), and with successive transformations of MM. At very low BS concentrations, in the outer vesicle monolayer definite BS/lipid aggregates are formed, the size and BS binding strength of which depend on the BS and lipid species involved. At increasing BS concentrations, binding to the membranes is hampered, and above a critical BS content, membrane stress due to asymmetric BS binding leads to formation of transient membrane holes, as shown by inulin release from the vesicles. Independent of the BS and lipid species, membrane solubilization starts at a ratio r = 0.3 of bound BS/lipid. Increasing phosphatidylserine, phosphatidylethanolamine, and cholesterol contents stabilize the lecithin membrane against BS to different degrees and in different ways, whereas the destabilization by sphingomyelin is probably due to the enhancement of the membrane gel-liquid transition temperature. Conjugation of the BS with glycine or taurine has a modulating effect on membrane hole formation, rather than on lipid solubilization. Diphenylhexatriene fluorescence anisotropy indicates a BS-induced drop of the internal membrane order and its restoration during membrane solubilization. At higher concentrations ursodeoxycholate induces additional condensation, whereas the other BS cause internal disorder in the MM. Above ratios r of approximately 8:1, we found a release of BS from these MM and suggest a rodlike structure for them. The results were discussed with respect to BS/membrane interactions during lipid excretion from the liver cell.

Bile Acids and Salts↗
PubMed1988

[The glutamic acid decarboxylase disc test. An approach for the simplification and speeding up of E. coli detection].

Although E. coli is certainly one of the best known and most widely examined bacterial species only few of their characters and properties were found suitable for the distinction of this species from other species especially from the coliform organisms. One of these rare characters is l-glutamic acid decarboxylase. The demonstration of the action of this enzyme, however, has hitherto been difficult and time consuming. A micro-method is described which permits the demonstration of l-glutamic acid decarboxylase--the glutamic acid decarboxylase disc test (gd-disc-test). The conditions and procedures required are described in detail. The validation of this test was done demonstrating in presence of gamma-aminobutyric acid by paper chromatography.

Chromatography, Paper↗