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Biomedical subjects

H Lippert

Publications and source records attributed to H Lippert.

At least 253 records · Page 14Linked to original sources

[Islet cell culture as a method of short-term preservation before islet transplantation].

Pancreatic islets were isolated by collagenase digestion of the pancreas from inbred Wistar rats and cultured at 20 mmol/l glucose and 5.3 mmol/l Mg++ for 4 days. About 1,000 cultured islets injected into the portal vein normalized the plasma glucose of severe diabetic rats induced by streptozotocin (45 mg/kg body weight). Spontaneous recovery of streptozotocin-treated rats was not observed in diabetic controls. Although the insulin response of transplanted rats after i.v. glucose injection (5 mmol per kg body weight) was significantly below control animals, the amount of insulin released was obviously sufficient to sustain a persisting normoglycemia of fed animals up to 1 year. The sufficient preservation of insulin content (I) and the rapid depletion of amylase content (A) of collagenase-treated pancreas fragments cultured for 48 h resulted in a significant rise in the I/A ratio. Because islet isolation is associated with islet loss, especially in the human pancreas, the short term culture enhances hopefully the possibilities for successful transplantation.

Animals↗

[Studies on the biomechanics of the human clavicle (author's transl)].

64 non preserved and 35 preserved clavicles were fractured in three defined positions in a bending test by a tension testing machine with electronic measurement of force. 30 non preserved bones were fractured in an axial infraction test. Force-deflection-diagrams were registered, and the values of maximum load, breaking load, ultimate deflection and energy were correlated to cross section and thickness of compacta. The significantly greater non preserved male clavicles are loadable at a higher level (medium breaking load about 1200 N) than female bones (medium breaking load abut 800 N). The breaking energy of the more flexible female clavicles is about 30% lower than those of males whereas elastic modulus of female clavicles is significant greater. Preservation has a significant influence on biomechanical properties of bones: ultimate deflection decreases; breaking energy, ultimate stress and elastic modulus increase. Breaking load is greatest in the middle portion of the clavicle, while deflection is greatest in the sternal portion. Removal of periosteum causes lower breaking load, deflection, ultimate stress and elastic modulus as well. With axial load clavicle fractures occur most frequently between middle and sternal third.

Age Factors↗

[Compression strength of human radii (author's transl)].

500 radius segments of a certain length of the corpses of 6 female and 36 male persons (medium age: 54.4 years) were chosen to determine the fracture load and the ultimate breaking stress by means of a machine testing the pressure power in a compression test. The mean fracture load is 7371 N and the average ultimate breaking stress 38 MPa. Fracture load and ultimate breaking stress of preserved specimens are significant higher than those of non preserved specimens. The bone, therefore, becomes more fragile by the preservation. Fracture load and ultimate breaking stress decrease distinctly with advancing years. The ends of the radii are clearly less capable of being strained than the middle parts of the shafts. The fracture load of the radius increases with the total length.

Adult↗

Is the low fertility rate after vasovasostomy caused by nerve resection during vasectomy?

Cross-sections of human spermatic cords and vasectomy specimens were prepared and the number and cross-sectional area of nerves were determined. On average, about one-half of all nerves in the near neighborhood of the vas deferens were resected during vasectomy. The total cross-sectional area of the nerves along the vasectomy specimens amounted to about one-half of the total area in the spermatic cord samples. The data support the hypothesis that removing nerves to the vas deferens during vasectomy could result in poor functional results after vasovasostomy, i.e., that powerful contraction of the proximal vas deferens and epididymis could be lacking.

Denervation↗

[Results of islet transplantation in diabetic dogs].

The influence of histocompatibility on islet transplantation in dogs was studied. Donors and hosts were chosen by help of the macrophage-electrophoresis-mobility test. By subtotal pancreatectomy and twice applying streptocotocin diabetes was successfully induced in recipient animals. Isolation of pancreating islets from the donor was done by means of the collagenase method combined with the Ficoll-gradient-separating technique. The grafting occurred via portal vein into the liver. Significant decrease of blood sugar during 10 weeks was observed in animals with good compatibility. This effect lasted only 14 days in cases of bad compatibility. Concentrations of insulin in the portal vein and superior caval vein 4 weeks after grafting was lower in cases with high-grade histoincompatibility. The duration of functioning of transplanted islets depends on the histocompatibility.

Animals↗

[Vagotomy and exocrine pancreatic secretion (author's transl)].

In dogs supplied with chronic pancreatic fistulas, there is no change of the basal exocrine secretion of volume three weeks after a bilateral truncular vagotomy. The normal initial reflex secretion during meal ingestion or glucose loading are abolished. On the whole, the secretory activity is reduced by about 50% after feeding. Secretions of volume and of enzyme protein are inhibited to the same extent, but that of bicarbonate is more strongly influenced. After vagotomy the inhibitory influence on all secretions of a rabidly produced hyperglycemia is reinforced. In pancreatic juice there is immunocreactive insulin activity (less than 1% fo the daily secreted amount). Insulin secreted in pancreatic juice after feeding is strongly reduced after vagotomy. This is the best reproducible proof of an influence on the exocrine pancreatic function of vagotomy.

Administration, Oral↗

[A model for different types of computers for recording, managing and evaluating data of middle ear operations (author's transl)].

A system is presented for recording, managing and evaluating data which is so simple that the clinician is able to handle it. The recording of data is done by marking on preformulated questionnaires without any coding of information by the doctor. From the documents, the key-punch operator then makes the punch cards (the alternative: marking documents that can be read directly by an optical mark page reader). The managing of data is done by an own program written in FORTRAN. It creates a tape-sentence of equal length and fixed format for each case. That means each case would contain the same variables, and the order of variables within each case would be the same. The ordering is done by means of an identification code which is derived from the employee numbering system and which makes it independent of all archive-based records. The evaluation is carried out by means of a data processing system which is available for most computers (SPSS). The preformulated questionnaires used for recordings, the program for managing the data and the evaluating procedure punch cards are described. All will be sent by demand.

Audiometry↗