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Biomedical subjects

G Zajicek

Publications and source records attributed to G Zajicek.

At least 145 records · Page 8Linked to original sources
PubMed1979

Cell production in the normal and lathyrogenic rat periodontal ligament (PDL).

Thirty male albino rats weighing 200 g. each were separated into two groups. 15 rats received 0.2% 3-amino propionitrile fumarate (BAPN) in drinking water. 15 rats served as controls. Within three weeks eruption rate diminished by 50%. On the 22nd experimental day each rat received one dose of 1 microCi/g. body weight tritiated thymidine (1.9 Ci/mM). 5 rats of each group were then killed after 1 hour; 1 week and 2 weeks. The PDL cell migration rate was evaluated autoradiographically. It diminishes proportionally with the eruption rate. In the BAPN treated animals, the mean total periodontal ligament (PDL) cell count is 55.5% higher than that of the control.

Aminopropionitrile↗
PubMed1979

The growth of the autotransplanted rat incisor tooth odontogenic organ.

74 rat incisor odontogenic organs were autotransplanted intradermally into the auricle. The animals were killed in groups of four up to eight months after grafting. Out of 61 grafts examined from the third week onward, 46% exhibited a typical odontogenic organ or a well differentiated tooth with pulp, vessels and nerve fibers. In 33% only scattered epithelial islands were formed. 21% of the grafts ended as osteodentin. Following the initial trauma leading to aseptic necrosis, the most primitive odontogenic organ cells survive to generate a new tooth. The grafted odontogenic organ resumes its existence as a complex structure which mobilizes its own vascular and nervous supply from the host dermis as evident from nerve fibers which penetrated the tooth pulp. Since all original nerve fibers of the graft had to be disconnected from their cell bodies, they obviously degenerated. Thus any nerve fiber observed in the regenerating tooth pulp had to be of dermal origin.

Animals↗
PubMed1978

The adaptation of a two-compartment cell renewal system to external demands. A study of the rat incisor inner enamel epithelium.

The inner enamel epithelium (IEE) covers the labial tooth aspect as a one cell layer which, when cut sagittally, appears as a longitudinal cell column extending from the tooth origin toward the periphery. Following sudden tooth shortening, the IEE responds by an increased cell production which later declines below normal values. The perturbation affects all cell kinetic parameters; the progenitor compartment, which initially increases, diminishes in size toward end of the experiment. The cell cycle transition times, which initially decline, rise toward the end of the experiment. The mean normal daily cell production rate of 70 cell % (i.e. 70 cells are produced by 100 progenitors) increases to 111 cell % and then declines to a low of 51 cell %. The IEE response typifies the behavior of other cell renewal systems such as intestinal epithelium and epidermis.

Animals↗
PubMed1978

On the potential of the adult rat incisor odontogenic organ to differentiate into two intact teeth.

The odontogenic organ of 10 male albino rats weighing 200 g has been exposed by a longitudinal incision through the masseter muscle. Its site could be identified as a bluish elevation of the mandible. Into this region through the bone, a 2 X 2 mm. tinfoil has been inserted, deep into the odontogenic organ. The tinfoil direction was generally parallel or slightly oblique to the tooth longitudinal axis. The animals were killed after 1 month. Their lower incisors in the bony sockets were fixed and decalcified, cut sagittally and processed histologically. In 3 sockets two separate teeth could be identified, a labial and a lingual tooth. Generally only the labial tooth was covered by enamel, in one case however both teeth exhibited a regular enamel layer. Both teeth were separated by a periodontal ligament and exhibited separate tooth cavities. This experiment demonstrates the capability of the odontogenic organ to reproduce a whole new complex organ, the tooth. A phenomenon hitherto observed only in Urodela in which a severed limb regenerates from primitive pluripotential stem cells known as blastema. Contrary to the newt however, the incisor blastema reproduces continuously throughout the life of the individual and responds to the tinfoil stimulus by a production of an extra tooth.

Animals↗
PubMed1978

Plasma digoxin levels and the interbeat interval signal in atrial fibrillation.

Fifty-eight patients with atrial fibrillation treated with digoxin were studied to determine the correlation between serum digoxin levels and the ventricular rate. The study was a computer-based exercise, processing a signal consisting of R-R intervals, derived by point-digitising electrocardiograms. The means, variances and centers of gravity of power-spectra from the signal were correlated with serum digoxin levels, the peripheral pulse and with each other. A poor negative correlation of -0.31 was calculated between the means of interbeat-intervals and serum digoxin levels. Other Ecg-derived rate parameters did not correlate any better with serum digoxin. The mean interbeat-interval in a group of patients with higher serum digoxin levels (2 ng/ml) was significantly (p is less than or equal to 0.05) shorter than in a group with a low level (1 ng/ml). The negative correlation and this significant difference are best explained by the gradual increase in the dose administered to non-responders by the attending physicians who did not fear over-dosage because of frequent serum level determinations. It is concluded that the serum digoxin level is a poor predictor of the ventricular rate in patients with atrial fibrillation because of marked individual differences. These are due to the poor representation by serum levels of drug concentration at the point of interest (A-V node) and the non-linearity of the chronotropic effect of digitalis.

Adult↗
PubMed1977

Urinary excretion of alpha-fetoprotein in rats on a cirrhogenic carbon tetrachloride regimen.

Alpha-fetoprotein was detected in the serum and urine of 2- to 9-mth-old rats subjected to protracted CCl4 poisoning. During the first 3 mth of the experiment, urinary excretion of AFP was found in 30-40 per cent. of the animals, increasing to 70 per cent. thereafter. The liver lesions progressed from acute parenchymal necrosis to cirrhosis, but hepatocellular carcinomas did not develop. Uptake of tritiated thymidine by the hepatocytes increased significantly but was constant throughout the experimental period. The findings are compared to the observations made during 3mDAB-induced hepatocarcinogenesis in the rat.

Animals↗
PubMed1977

Excretion of alpha-foetoprotein in the urine of rats during exposure to 3'-methyl-4-dimethylaminoazobenzene.

Female rats were maintained on standard laboratory diet, Miller's diet or Miller's diet containing 3'MeDAB. Animals fed standard or Miller's diet did not excrete alpha-foetoprotein (AFP) in their urine. Early appearance of AFP was demonstrated by examining the urine of rats on the 3'MeDAB regimen. The incidence of positive urine samples was high between the 5th and 7th week of the experiment. It thereafter declined, but from the 3rd month it steadily rose and reached a maximum of 80% at about 10 months. Though urinary excretion of AFP was irregular in individual animals, several positive urine samples were obtained from all rats followed for more than a few months. The urine of 90% of hepatoma-bearing rats contained AFP at the time of killing. The incidence of elevated serum AFP levels as determined by immunodiffusion, increased with the duration of the experiment, but was still only 70 percent in rats fed 3'MeDAB for over 34 weeks. The severity of the hepatic alterations, as well as hepatocytic uptake of [3H]thymidine, increased with time. The serum of animals fed the standard diet was negative, whereas AFP was very infrequently detected in the serum of rats given Miller's hypoprotein diet. The results demonstrate that, in a population exposed to hepatocarcinogenic agent, the recurring detection of urinary excretion of AFP is a useful indicator of the high risk of developing hepatomas.

Animals↗
PubMed1977

Role of attrition and occlusal contact in the physiology of the rat incisor: XL Kinetics of inner enamel epithelium during severely impeded eruption.

Under conditions of high impediment, the rate of eruption of the rat incisor decreases considerably as does the rate of cell production of the inner enamel epithelium (IEE). The latter is acomplished by a decrease in the size of the proliferative compartment and an increase in the generation time. A linear relation exists between IEE cell production and tooth eruption, and cell production can be estimated from eruption measurements.

Animals↗
PubMed1976

Alpha-fetoprotein and liver cell proliferation in rats fed choline-deficient diet.

Liver 3H-thymidine labelling index and serum AFP were determined in rats fed a standard laboratory or choline deficient diet. A significant increase in the rate of liver cell proliferation was evidenced in animals on the deficient diet. Furthermore, elevated serum AFP levels were detected in a proportion of these rats. It is suggested that increased synthesis of AFP corresponds to liver cell regeneration secondary to hepatic damage.

Animals↗