The internal variability of the mesothelium during regeneration following trauma applied at various times of the day

A quantitative investigation of the mitotic activity (MA) dynamics, size of the cells, amount of their mutual contacts (as an index of the epithelial layer regulation) and amount of nucleoli in the nuclei of mesothelium after a trauma, performed at 9 a.m. and at 9 p.m. has been carried out. The investigation lasted for 96 h. According to statistically significant differences two zones are revealed: a nearer and a remote one. Changeability of mesothelium increases in both zones, but it is greater manifested in the nearer zone. MA dynamics in both zones demonstrates a quick growing and a similarly quick drop, except the remote zone after the morning operation, where MA decreases slower. Amount of the cells, whose nuclei contain more nucleoli than in the norm, increases before the development of the MA waves. MA increase is accompanied with decreasing size of the cells. Normalization of MA and size of the cells occur approximately simultaneously. This process is more manifested after the morning operation, and after the evening one, normalization of these signs, during the time of observation, is reached only in the remote zone. Disorganization of mesothelium, as a tissue system, precedes the MA increase. A significant difference of this sign from the control takes place only in the nearer zone after the morning operation. As a whole, the changeability of mesothelium is more manifested after the morning operation.     

Space-time characteristics of DNA synthesis in mesothelial cells of the rat after surgery at different times of the day

Differences in the DNA synthesis dynamics (according to the label index-LI) and those of mitotic activity (MA) in the mesothelium of the rat parietal peritoneum have been studied after burn performed at 9 AM, or at 9 PM. A number of peculiarities in the regeneration character are dependent on the day time of the operation. Immediately after the PM operation inhibition of both DNA synthesis and MA is manifected more distinctly and lasts longer, but then activation of the processes occurs more intensively the LI and MA values are greater than after the AM operation. Drop in the LI and MA takes place also with a greater rate after the PM operation, but their absolute values are kept higher up to the 7th day. Despite the fact that the reaction after the AM operation is comparatively weak, it is more rhythmical: against the background of general dynamics the fluctuations are more distinctly manifested, their period is nearly similar to the circadian. Increase in the proliferative activity is accompanied with a widening of the zone, where the dividing cells are situated. After the PM operation the wavy character of the process is expressed only in the pattern of the spatial organization of the regenerating mesothelium: nearly at regular intervals the area of the MA distribution becomes widen or narrow in turn. Thus, the LI and MA dynamics in the regenerating mesothelium depend on the circadian phase of the organism's state at the moment of the operation.     

Reactive growth of the mesothelium of the parietal leaf of the peritoneum]

In the process of reparative regeneration of the mesothelium caused by suturing of a portion of the jugular vein into the peritoneum defect the inflammatory mesothelial growings are formed. They have different configuration, consist only of the mesotheliumor the connective tissue covered with the mesothelium and are observed from the 4th day till 3 months after operation, being always faced to the abdominal cavity. The capacity of mesothelial cells to high mitotic activity and wedging out from the layer underlies the formation of posttraumatic structures of the mesothelium.     

The influence of environmental factors upon induced compensatory hyperplasia in the rat liver

This study has examined the influence of a controlled environment upon the nature of the compensatory hyperplasia which occurs in the rat liver after two-thirds partial hepatectomy. Rats were adapted to a reversed lighting schedule (lights off 09.30 to 21.30 h), and food was only available during the first 8 h of the dark period. Partial hepatectomies were performed at either 10.00, 16.00 or 20.00 h, and the response over the first 36 h monitored by 2-hourly measurements of the flash tritiated thymidine labelling index and the mitotic index. DNA synthesis was initiated within 16-18 h of operation, irrespective of when hepatectomies were performed, though the ensuing patterns of DNA synthesis were rather different. On the other hand, the initiation of mitotic activity was very much dependent upon the time of day that resections were carried out. Hepatectomy at 20.00 h resulted in a rise in mitotic activity some 22-24 h later, but hepatectomy at 10.00 h caused a further 6 h delay in this rise. The onset of mitotic activity appeared to be related to recent feeding, and it is proposed that in the absence of recent nutrition, DNA-synthesizing hepatocytes may have an extended tS and/or tG2.     

The role of ACTH(5-8) and beta-MSH(5-8) fragments in the organization of the self-stimulation reaction

The experiments on rats have shown that intraperitoneal administration of ACTH5-8 fragments in a dose of 40 ng per kg altered considerably the character of self-stimulation reaction and the behaviour of rats. Searching activity and self-stimulation reaction were intensified, with the latter characterized by the onset of aversive components, that disappeared 24 hours later. Activation depended on the site of stimulation. Two phases of activity were noted (the first 0.5-1 h and the second 4.5-6 h after ACTH5-8 injection). beta-MSH5-8 fragment, when injected intraperitoneally in a dose of 20 ng per kg, had no effect on self-stimulation reaction and the behaviour of animals.     

Effect of adaptation to high-altitude conditions on the circadian rhythm of the epithelial mitotic activity in the convoluted kidney tubules in white rats

It has been established in experiments on 280 white randombred male rats weighing 100-120 g that the lifting of the animals from the valley (820 m above the sea level) to the mountains (3379 m above the sea level) brings about within the first day marked suppression of the mitotic activity of the epithelium of involuted renal tubules. This activity increases beginning from the end of the first week, approaches the control value by the 30th day of adaptation and almost completely returns to normal by the 60th day of the animals' stay in the mountains. The circadian rhythms of the mitotic activity appeared undisturbed and was monophasic in nature.     

Change in cerebral bioelectric activity during whole body hypothermia and regional cooling of the head]

Two series of experiments were conducted on dogs. In the first series of experiments dogs were subjected to deep hypothermia with an external chilling of the organism; in the second series-to the isolated deep hypothermia of the head with the maintenance of normothermia in the organism. Bioelectrical activity of the brain and circulation minute volume were recorded in the animals of both series. As revealed, depression of the bioelectrical activity was more pronounced and a prevalence of slow waves was observed in general hypothermia; at the same time a more even reduction of the electrical activity in all the EEG frequencies under study was seen in the series with local hypothermia. A reduction of the circulation minute volume was also more pronounced in the first series of experiments; in the authors' opinoin this was associated with the difference in the character of the EEG evolution with the same depth of hypothermia of the brain.     

Effect of saline solutions administered parenterally in different postoperation phases on the regeneration of rat liver after partial hepatectomy

Two series of experiments were carried out on female laboratory rats with a mean pre-operation weight of 250 +/- 30 g, fed up to the time of the experiment on a standard laboratory diet with water ad libitum. In the first series the rats were subjected to 65-70% partial hepatectomy (PH) or to laparotomy (LAP) and their serum Na+, K+, Cl- and total calcium concentrations were determined 6, 12, 18 and 24 h after the operation. At given postoperation intervals the serum Na+, Cl- and total calcium concentrations in hepatectomized animals were lower than in the intact controls, while the K+ concentration was higher. In the second series of experiments, the rats were given infusions of physiological saline or Ringer solution at different intervals (1-6, 7-12, 1-12 and 1-24 h) after PH. Specific DNA activity in the liver, the hepatocyte mitotic index, the total DNA content of the liver and other indicators show that physiological saline infusions had an inhibitory, or at most a neutral effect on the initiation of liver regeneration, while the effect of the infusion of Ringer solution on the initiation of liver regeneration, in most of the given intervals, was indifferent. The regeneration response depends on the post-PH phase in which the solution is infused.     

The basalis of the primate endometrium: a bifunctional germinal compartment

Radioautographic analysis of epithelial and stromal cell proliferation in the primate endometrial functionalis and basalis (rhesus monkey) has identified horizontal zonal patterns of mitotic activation and inhibition during natural menstrual cycles. At 1 h after a single i.v. injection of [3H]thymidine, mitotic activity in endometrial biopsies (hysterotomy) was determined on 9 days from the late proliferative to the late luteal phase (-2 days to + 14 days relative to the estrogen [E2]peak). Labeling indices (LIs) were determined within glandular segments of the 4 horizontal endometrial zones: Transient functionalis Zone I (luminal epithelium) and Zone II (uppermost gland); Germinal basalis: Zone III (middle gland) and Zone IV (basal gland). The size of the dividing epithelial populations (LI) differed zonally. During E2 dominance (-2 days to +3 days), the epithelial LIs of functionalis I (10 +/- 0.3%) and II (9.8 +/- 1.0%) were greater than those of basalis III (5.8 +/- 0.2%) and basalis IV (3.7 +/- 0.8%). During progesterone (P) dominance (+5 days to +14 days), epithelial mitosis was strongly inhibited in functionalis I (4.3 +/- 1.9%), functionalis II (0.8 +/- 0.2%), and basalis III (1.4 +/- 0.5%). Thus germinal basalis III was linked functionally with transient functionalis I and II by periovulatory uniformity in epithelial proliferation and postovulatory mitotic inhibition. A unique mitotic pattern set basalis IV apart from other zones by a steady rise in LI from 1% (-2 days) to 11% (+10 days). The LIs for stromal fibroblasts remained quite uniform in basalis IV but varied in other zones. Thus the postovulatory primate basalis was a distinct bipartite compartment in which the mitotic rate in basalis IV glandular epithelium increased steadily whereas that of basalis III was strongly inhibited. The remarkable enhancement of epithelial mitotic activity in basalis IV may reflect expansion of the stem-progenitor cell population for gestational growth or for post-menstrual regeneration.     

Differentiation of mesothelial cells during their reparative regeneration

The investigation on regenerative processes of mesothelium of the parietal peritoneum was performed in 120 white mice under the effect of certain irritants producing lesions various in depth and intensity. Nuclear-cytoplasmic relations and ultramicroscopic cellular rearrangement were studied during the process of differentiation of the mesothelial regenerate. Two periods of the regenerative process are stated and it is demonstrated that rearrangement of the mesothelial cells and the mode of their division depend on intensity of the lesions. When the peritoneal lesion is severe, at the first stages of regeneration (the 1st period) rearrangement of cells towards their hypertrophy and increased functional activity is predominant in the mesothelium. Further (the 2d period), the number of mitotically dividing cells is increasing in the mesothelial regenerate and in rearrangement of the mesothelial cells the processes connected with a partial loss of their signs of specialization predominate. The transition from one period into another is gradual and duration of each depends on intensity of the lesion.     

Mitotic chromosomes are constrained by topoisomerase II–sensitive DNA entanglements

We have analyzed the topological organization of chromatin inside mitotic chromosomes. We show that mitotic chromatin is heavily self-entangled through experiments in which topoisomerase (topo) II is observed to reduce mitotic chromosome elastic stiffness. Single chromosomes were relaxed by 35% by exogenously added topo II in a manner that depends on hydrolysable adenosine triphosphate (ATP), whereas an inactive topo II cleavage mutant did not change chromosome stiffness. Moreover, experiments using type I topos produced much smaller relaxation effects than topo II, indicating that chromosome relaxation by topo II is caused by decatenation and/or unknotting of double-stranded DNA. In further experiments in which chromosomes are first exposed to protease to partially release protein constraints on chromatin, ATP alone relaxes mitotic chromosomes. The topo II–specific inhibitor ICRF-187 blocks this effect, indicating that it is caused by endogenous topo II bound to the chromosome. Our experiments show that DNA entanglements act in concert with protein-mediated compaction to fold chromatin into mitotic chromosomes.     

Dexyribonucleic acid polymerases of BHK-21/C13cells. Relationship to the physiological state of the cells, and to synchronous indution of synthesis of deoxyribonuleic acid.

BHK-21/C13 cells were grown in culture under conditions that provided exponentially growing cells and quiescent cells, by modifying the concentration of serum in the growth medium. The high-molecular-weight DNA polymerase (DNA polymerase I) from exponentially growing cells accounted for 90% of the total polymerase activity; the low-molecular-weight DNA polymerase (DNA polymerase II) accounted for the remaining 10%. In quiescent cells, DNA polymerase I contributed only 39% of the total polymerase activity and DNA polymerase II 61%. The total amount of DNA polymerase I in exponentially growing cells was 11.3-fold greater than that in quiescent cells, whereas the amount of DNA polymerase II appeared to be relatively independent of the physiological state of the cells. In an extension of these experiments, cells in a quiescent state (Go cells) were stimulated by the 'serum-step-up' method of Burk (1970) to grow and to enter a synchronous wave of DNA synthesis (S-phase cells), 87% of the cells synthesizing DNA at 20 h after the 'serum-step-up'. During the synchrony experiment, the total cytoplasmic and total nuclear DNA polymerase activities each increased about 4-fold in parallel with the increase in the rate of DNA synthesis. Cytoplasmic polymerase activity was always greater than nuclear polymerase activity. The increases observed were maximal at 20 h after 'serum step-up'. By 26 h, there was a decrease in enzyme activity (8% for cytoplasmic polymerase and 16% for nuclear polymerase, both relative to the maximum at 20 h), but the rate of DNA synthesis had declined by 37% relative to the maximum at 20 h. In Go cells, DNA polymerase II (mol.wt. 46000 +/- 4000) was the predominant species, there being twice as much of it as of the total DNA polymerase I. In these cells there was little DNA polymerase IC and ID; the amounts of IA (mol.wt. 900 times 10(3)-1100 times 10(3)) and IB (mol.wt. 460 times 10(3)-560 times 10(3)) were about equal but small.     

Inhibition of chromosome separation in fertilized starfish eggs by kalihinol F, a topoisomerase I inhibitor obtained from a marine sponge

Kalihinol F, a naturally occurring diterpene from a marine sponge, Acanthella sp., inhibited chromosome separation in fertilized starfish (Asterina pectinifera) eggs but allows the first cleavage to occur, thereby forming unseparated metaphase chromosomes which were elongated between the two daughter cells. The chromosomes were eventually torn off in the embryonic cells. Most of the cells gradually lost the chromosomes during the cell cycle progression. The embryonic development halted at the morula stage just before the onset of blastulation. The mitotic failure occurred when kalihinol F was applied to a fertilized egg during the second meiotic process, but not after the completion of the second meiotic division. Kalihinol F inhibited topoisomerase I activity in vitro, but had no effects on activities of DNA polymerases alpha, beta, and gamma, and of topoisomerase II. These results suggest that the topoisomerase I plays an essential role in meiosis II in this species.     

Circadian rhythms of the parameters of the mouse esophagus epithelial cell kinetics

Circadian rhythms of the mitotic activity, DNA synthesis and the parameters of the mitotic cells of the mouse esophagus epithelium were studied during the periods of maximum and minimum proliferation. The number of mitoses and DNA-synthetizing cells increases rhythmically at 1--7 a. m. from 22 p. m. to 4 a. m., respectively. When 3H-thymidine was injected to the mice at 2 a. m., tG2min was 1h; tG2+1/2 M was 2h; tS was 7.1; tG1+1/2 M was 2h; tS was 7.1; tG1+1/2 M was 15.9h. When 3H-thymidine was injected at 2 p. m., tS rose up to 8.2 and tG1+1/2 M up to 14.8h. The mitotic cycle in both series of experiments totalled 25 h. Thus, the duration of various phases of the mitotic cycle depends on the time of the day and correlates with circadian rhythms of the mitotic activity and the number of DNA-synthetizing cells. Duration of the mitotic cycle of the cells passing through it at varying time of the day is the same and approximates the period of the circadian rhythm of mitoses and DNA synthesis in esophagus epithelium.     

Experimental anatomical basis for a new method of revascularizing the femoral head for the treatment of avascular necrosis

Two series of experiments were performed in rabbits of both sex at the age of 2-6 months. In I series (42 rabbits) the modelling of Perthes' diseases was performed by a lesion produced in the proximal diaepiphysial femoral growth zone. Character and course of pathological processes in the femoral head and neck were studied. They were mainly correspond to 5 clinical roentgenological stages of Perthes' disease. In II series (52 rabbits) with the model of Perthes' disease the suggested operation on revascularization of the femoral head by means of a periosteal muscular graft on a feeding peduncle was applied. Histological, angiological, roentgenological investigations and the method on indication of radioactive phosphorus (P32) demonstrated good vascularizational and reparative properties of the transplant applied. In 50 patients with Perthes' disease the result of a conservative treatment were studied. In 25 patients the operation on revascularization of the femoral head by means of a periosteal muscular transplant on a feeding peduncle was applied according to the technique suggested. The analysis of the treatment results demonstrated that restoration of the femoral bone configuration and that of functioning of the coxofemoral joint occurred sooner, further progressive course of the disease was stopped, duration of treatment was shorter as compared to the conservative methods. The operation suggested could be applied together with other operative methods for treatment of Perthes' disease.     

Mitotic activity of regenerating rat liver following stimulation with alpha- and beta-adrenoreceptors

A study was made of the effect of stimulating alpha- and beta-adrenoreceptors on the mitotic activity of the rat regenerating liver following resection. Mesaton, a stimulator of alpha-adrenoreceptors, and isadrin, a stimulator of beta-adrenoreceptors, in a dose of 0.2 mg/kg were injected one hour before liver resection or 30 min, 8 and 24 h after operation. In all experimental groups, mesaton gave rise to an increase in the mitotic index without lowering the coefficient of the mitotic phases. The least pronounced stimulating effect was attained when mesaton was injected 9 hours after partial hepatectomy. Isadrin reduced the mitotic activity as judged from the decrease of the coefficient of the phases and augmentation of the number of binuclear cells. The experiments confirmed a previously advanced assumption that stimulation of alpha-adrenoreceptors favours while that of beta-adrenoreceptors reduces cell proliferation.     

Effects of ozone on meiotic chromosomes of Vicia faba.

All of the levels of ozone used in these experiments caused morphological damage to plants of Vicia faba L., but only the dose of 200 parts per hundred million for 4 h or 8 h caused chromosomal damage in the microsporocytes. Significant chromosomal damage appeared 24 h after fumigation in metaphase I and anaphase I - telophase I but no significant damage was found in anaphase II - telophase II. This observation suggests that chromosomes are more susceptible to ozone during early stages of meiosis than at later stages. Chromosomal damage was of two types: physiological, as suggested by chromosome stickiness and physical, as indicated by bridges, fragments, and micronuclei.     

Biochemical studies on goat oocytes: Timing of nuclear progression, effect of protein inhibitor and pattern of polypeptide synthesis during in vitro maturation

Temporal progression of nuclear events of goat oocytes matured in vitro was studied by adding a specific inhibitor to the culture medium at different time points, to investigate protein synthesis requirements and its pattern during in vitro maturation. Goat cumulus-oocyte complexes (COCs) were matured in vitro in TCM 199, fixed at different time intervals and stained with orcein to assess nuclear changes. The germinal vesicle (GV) stage was found to be present at 0 h, chromosomal condensation stage was observed at 8 h, metaphase I at 12 to 14 h, and metaphase II was begun after 16 h of maturation and was nearly completed at 24 h. Protein synthesis inhibitor, cycloheximide, blocked oocyte maturation at germinal vesicle breakdown(GVBD), if added to the maturation medium between 0 to 4 h, suggesting that protein synthesis is required for GVBD. The transition from metaphase I to metaphase II was also protein synthesis-dependent, as observed when cycloheximide was used between 8 to 10 h of culture. When cycloheximide was added from 12 h of culture onwards, nuclear progression to metaphase II was progressively restored, but many chromosomal abnormalities were noted. Changes in the protein synthesis pattern were studied by radiolabeling of oocytes with [(35)S]-methionine at 0, 7, 12 and 24 h of culture, corresponding with GV, GVBD, metaphase I and metaphase II stages. A polypeptide of 28.1 KDa appeared as a major band at the GV stage, and its size decreased greatly and disappeared after the GVBD stage. Three new polypeptides (35, 36.5 and 39 KDa) appeared at GVBD and were detectable at metaphase II. In conclusion, the synthesis of proteins is required for the maintenance and transition of goat oocytes from GV to metaphase II during in vitro maturation.     

Development of the photosynthetic apparatus during light-dependent greening of a mutant of Chlorella fusca

The formation of chlorophyll, cytochrome f, P-700, ribulose bisphosphate carboxylase as well as photosynthesis and Hill reaction activities were tested during the light-dependent greening process of the Chlorella fusca mutant G 10. Neither chlorophyll nor protochlorophyllide was detected in the darkgrown cells. When transferred to light the mutant cells developed chlorophyll and established its photosynthetic capacity after a short lag phase. In the in vivo absorption spectra a spectral shift of the red absorption peak position from 674 to 680 nm was indicated during the first 3 h of greening. Cytochrome f was already present in the dark-grown cells, but during the greening phase a threefold increase in the cytochrome f content could be seen. At the early stages of greening a characteristic primary oscillation in the content of cytochrome f was observed. P-700 was lacking in the dark and during the first 30 min of illumination. From the first to the second h of light a forced synthesis of P-700 took place and the time-course curve for the ratios of P-700/chlorophyll rose to a sharp maximum. The synthesis of P-700 started together with photosystem I activity and showed similar kinetics. We found the simultaneous appearance of photosystem II, photosystem I, and photosynthetic activities 30 min after the beginning of the illumination. Based on chlorophyll content they attained maximum activity after 2 h of light, but at this time photosystem I capacity proved to be remarkably higher than photosynthetic and photosystem II activities. Highest carboxylase activity existed in darkgrown cells. During the greening process the activity of the enzyme decreased continuously. After 2 h of illumination chlorophyll synthesis partially served to increase the size of the photosynthetic unit, which consequently led to a decrease in the light energy needed to saturate photosynthesis and also to a decrease of photosynthetic rate based on chlorophyll content.Abbreviations Chl chlorophyll - Cyt f cytochrome f - DPIP 2,6-dichlorophenolindophenol - EDTA ethylenediaminetetraacetic acid - GSH glutathione - LH light-harvesting - PS photosystem - RuBP ribulose bisphosphate     

An electromyographic study of uterine activity during normal and progestogen-regulated estrus in the ewe

Myometrial electrography was performed by means of chronically implanted electrodes in the base, the middle and the tubal end of both the uterine horns of six Serres ewes at normal and progestogen-regulated estrus. During the first 24 h of normal estrus, myometrial electrical activity was characterized by intermittent spike bursts (Pattern I activity), occurring at about the same frequency in the three sites of both horns (middle of the right horn: 44.13 +/- 6.07 / 30 min). This pattern was then gradually transformed so that 36 h after the beginning of estrus, there was mostly only episodic activity consisting of 18.22 +/- 3.44 bursts, lasting 6.50 +/- 2.42 mins, and recurring at 30.51 +/- 16.24 min intervals simultaneously in both horns (Pattern II activity). During Patterns I and II, the respective ratios of descendingly to ascendingly propagated bursts were 2.65 and 0.78. Pattern I activity also occurred during the first 24 h of progestogen-regulated estrus, but the frequency of the bursts of spikes although occurring in the tubal ends of both horns at about the same rate as in Pattern I at normal estrus, gradually decreased towards the uterine body, (tubal end: 44.34 +/- 4.28, middle: 40.14 +/- 5.42, and base: 33.22 +/- 4.82 / 30 min). Then Pattern I activity was transformed into a miscellaneous pattern instead of into Pattern II. In the progestogen-regulated estrus, the ratio of the descending to the ascending propagations of spikes during Pattern I activity rose to 5.11.