Biomedical subjects
Publications and source records attributed to Y Tong.
By means of HPLC method, yunaconitine and talatisamine contained in 10 samples of folk drug Caowu (aconite) have been analysed. The result shows that in 3 species both yunaconitine and talalisamine are present, and in 7 species only yunaconitine is found. The contents and HPLC chromatograms of these alkaloids vary with the samples.
It has been recently demonstrated that sex steroids can negatively regulate beta-endorphin content as well as proopiomelanocortin (POMC) mRNA levels in the rat basal hypothalamus. In order to verify whether or not all the POMC neurons are equally affected by sex steroids, we arbitrarily divided the arcuate nucleus rostro-caudally into four equal portions and used an in situ hybridization technique to evaluate POMC gene expression in these different regions of the arcuate nucleus in the female rat. It was shown that ovariectomy induced an increase in mRNA levels in the most rostral region of the arcuate nucleus, an effect which was reversed by the concurrent administration of estradiol and dihydrotestosterone. On the other hand, estrogen administration to ovariectomized animals produced a marked depression of mRNA levels in all the regions of the arcuate nucleus with the exception of the most caudal one. These results suggest that sex steroids exert their action in subpopulations of POMC neurons.
Twelve loci have previously been identified in tomato (Lycopersicon esculentum) that control the intensity and distribution of anthocyanin pigmentation; these are useful genetic markers because they encode phenotypes that are readily visualized in the hypocotyls of emerging seedlings. In order to obtain molecular probes for tomato anthocyanin biosynthesis genes, we isolated two cDNAs which encode chalcone synthase (CHS), one of the key enzymes in anthocyanin biosynthesis, from a tomato hypocotyl cDNA library. By comparing their nucleic acid sequences, we determined that the two CHS cDNAs have an overall similarity of 76% at the nucleotide level and 88% at the amino acid level. We identified hybridization conditions that would distinguish the two clones and by Northern analysis showed that 1.5 kb mRNA species corresponding to each cDNA were expressed in cotyledons, hypocotyls and leaves of wild-type seedlings. Hybridization of the cDNAs at low stringency to genomic blots indicated that in tomato, CHS genes comprise a family of at least three individual members. The two genes that encode the CHS cDNAs were then placed onto the tomato genetic map at unique loci by restriction fragment length polymorphism mapping. We also assayed the activity of CHS and another enzyme in the anthocyanin pathway, flavone 3-hydroxylase, in hypocotyl extracts of wild-type tomato and a number of anthocyanin-deficient mutants. Five mutants had reduced CHS activity when compared to the wild-type controls. Of these, three were also reduce in flavone 3-hydroxylase activity, suggesting a regulatory role for these loci. The other two mutants were preferentially reduced in CHS activity, suggesting a more specific role for these loci in CHS expression.
The ontogeny of proopiomelanocortin (POMC) gene expression in the intermediate lobe of the pituitary was studied in rats of both sexes using quantitative in situ hybridization performed on fixed pituitary sections. Electron microscopic studies revealed in the adult animal the hybridization signal was found in all the secretory cells of the intermediate lobe and only in the POMC cells in the anterior lobe, thus indicating the specificity of the technique used. Hybridization signal was first detected on day 15 of gestation and progressively increased during foetal life. After birth, POMC and mRNA levels markedly increased so that, in one-day old animals, they were 4.5-fold higher than at the end of gestation. Thereafter, mRNA concentrations steadily increased to reach a plateau at 60 days of age in both sexes. No sexual dimorphism was observed at any ages. The results indicate that the development of intermediate lobe cells occurs mostly after birth. They are consistent with previous results indicating a 200-fold increase in the levels of POMC-derived peptides from birth to adulthood.
In order to evaluate the possibility that ANF might be associated with brain maturation, we have studied the distribution of ANF binding sites as a function of brain development in the rat. Using in vitro autoradiography, we have observed that ANF binding first appeared before the 13th day of foetal life. In some brain structures, the changes in ANF binding concentration and distribution were dramatic during maturation. In 13-day old foetus, specific ANF binding was observed in cerebral cortex and olfactory bulb. On the 17th day of foetal life, two labeled layers were observed in the cerebral cortex: the basal layer (cortical plate) and the superficial layer. With further development, the ANF binding of the cortical plate decreased whereas the labeling increased in the superficial layer so that 9 days after birth a strong labeling was observed in the superficial layer of the cortex. Thereafter the density of ANF binding rapidly diminished and almost no specific labeling could be detected in the cortex of adult animals. In the hippocampus and amygdaloid complex, ANF binding was first detected at birth and increased rapidly in the following days to reach maximal concentration 5 days after birth. Then, the binding gradually decreased with age and completely disappeared in adult animals. In some other structures, such as the habenula, cerebellum, thalamus and some hypothalamic nuclei, the specific ANF binding appeared around the time of birth, increased until adulthood was reached, and then remained stable. These results indicate that ANF binding sites are transiently associated with some brain structures during maturation and suggest that ANF might be involved in brain development.
We have recently reported that, in the rat pituitary, prolactin (PRL) is synthesized and stored in two different cell types: the typical PRL cell characterized by the presence of large irregular secretory granules and another cell type containing small round secretory granules. Since the secretion of PRL is stimulated by estrogens, we decided to investigate the effect of gonadectomy and estradiol (E2) replacement therapy in female rats on both cell types using a combination of in situ hybridization and immunostaining. Gonadectomy induced a marked decrease in hybridization signal and an almost complete disappearance of the classical PRL cells. The most abundant PRL cells were the small-granule-containing cells and other PRL cells characterized by the presence of both small and large granules. These changes in the PRL cell population were completely prevented by E2 administration to castrated animals. These studies indicate that E2 cannot only regulate PRL mRNA but also induce important morphological changes in PRL cell types.
The aim of the present study was to investigate the potential of restriction endonuclease analysis (REA) for the identifying and typing of Actinobacillus actinomycetemcomitans (Aa). Bacterial chromosomal DNA was extracted and digested with BamHI, HindIII, Sal I and Xho I respectively and separated by agarose gel electrophoresis. DNA fragment patterns of Aa and Haemophilus aphrophilus differed strikingly from each ether. The patterns of Aa FDC Y4 and Aa ATCC 29523, belonging to two different serotypes, also differed notably. Among the 4 enzymes used, Sal I and Xho I gave the most satisfactory results. The results of our work suggested that REA could be used to identify and type Aa. REA is stable, sensitive, accurate and reproducible. The method might be valuable in molecular epidemiologic studies on periodontopathic organisms.
The first upper molars in 140 young adult wistar rats were moved buccally by fixed appliance. The phenomena of tooth movement and its periodontal tissue changes has been investigated systematically. The results indicate that the tooth movement can be divided into three periods: rapid movement reversal movement and slow persistent movement. The compression of the periodontium was the main cause of the rapid movement; The rising of the tissue pressure caused by tissue edema probably resulted in the reversal movement and the remoulding of the alveoli at the pressure side caused the slow, persistent movement. This experiment also indicates that the total distance of tooth movement at the end of each experiment is not related to the magnitude of the force applied. In general, the heavy force makes the extent of the necrosis larger and the time necessary for tissue recovery longer. The above phenomena suggest that in clinical practice, it is important to acquire rapid, effective tooth movement while avoiding undue tissue injury.
Three alkaloids contained in Aconite roots, aconitine, mesaconitine and hypaconitine, were determined by HPLC. 15 samples (8 species) of Aconite roots were analysed. The results reveal that most of them contain the three alkaloids in different contents, and some of them contain one or two alkaloids.
The distribution of atrial natriuretic factor (ANF) binding sites was investigated in the central nervous system of the frog Rana ridibunda using the technique of in vitro receptor autoradiography by means of [125I]-labeled ANF-28. The anatomic distribution of ANF recognition sites was determined on Kodak ARX films apposed onto tissue sections, and their distribution was examined in greater detail by analysis of autoradiograms generated by using emulsion-coated sections. The highest levels of ANF binding sites were found in the olfactory bulb, the dorsal pallium, the septum, the habenular nucleus, the dorsal infundibular nucleus, the interpeduncular nucleus, and in the tectum. Moderate levels of ANF binding sites were observed in the thalamus and throughout the mesencephalon, whereas low levels were detected in the lateral and medial pallium, the medial forebrain bundle, and the nucleus rotondus. In the pituitary gland, the neural and distal lobes were densely loaded with ANF binding sites, whereas no autoradiographic labeling was observed in the pars intermedia. In general, there was a good correlation between the location of ANF receptors and the distribution of ANF-containing neurons, as previously determined by immunocytochemistry. Together these results support the view that ANF may act as a neurotransmitter or a neuromodulator in various regions of the frog brain.
Recent immunoelectron microscopic studies have shown that immunoreactive prolactin (PRL) in rat pituitary can be detected not only in typical PRL cells, characterized by large secretory granules, but also in another type of cell, which contains small secretory granules. To determine whether or not these two cell types are involved in PRL biosynthesis, we developed a procedure to investigate PRL gene expression by using in situ hybridization at the ultrastructural level. Rat pituitary was fixed and vibratome sections were incubated with a PRL [35S]-cDNA probe and subsequently flat-embedded in Araldite. Semi-thin and ultra-thin sections were processed for autoradiography. The results indicate that only the two PRL cell types were labeled. When immunolabeling for PRL was applied to ultra-thin sections, only immunopositive cells were seen to contain silver grains. In these cells the silver grains were associated with the rough endoplasmic reticulum and nucleus. When a growth hormone (GH) [35S]-cDNA probe was used as a control, only GH-secreting cells were labeled. This study confirms that the two PRL cell types are involved in biosynthesis of PRL. Moreover, this simple in situ hybridization technique provides a new approach to accurately localize mRNA in complex tissue and to investigate the subcellular distribution of mRNA under differing experimental conditions.
Estrogens are known to exert specific stimulatory effects on basal and dopamine-inhibited PRL secretion and synthesis as well as on PRL gene expression. However, dihydrotestosterone (DHT) and progesterone (P), although inactive alone, can reverse the effect of 17 beta-estradiol (E2) on PRL release both in vivo and in vitro. Using castrated male rats, we have studied the effect of E2 (0.25 micrograms), P (2 mg), or DHT (100 micrograms) administered twice daily for 14 days alone or in combination on pituitary PRL mRNA levels measured by quantitative in situ hybridization. Treatment with E2 increased the accumulation of PRL mRNA by about 2.6-fold. Administration of P or DHT alone failed to modify PRL mRNA concentrations. However, DHT could prevent by 80% the stimulatory effect of E2 on PRL mRNA levels. Similar results were obtained by dot blot hybridization assay. The effects of sex steroids on PRL mRNA were closely paralleled to pituitary PRL content measured by RIA. The present data demonstrate that the effect of sex steroids on immunodetectable PRL result from a modulation of PRL mRNA accumulation. The sexual dimorphism observed in pituitary PRL content results from a 3.5-fold greater accumulation of PRL mRNA in intact females than in male rats. These results also clearly show that quantitative in situ hybridization is a powerful tool in the investigation of the regulation of gene expression in addition to providing valuable information on the localization of specific mRNA.
Eighty-five patients with a total of 103 foci of chronic hematogenous osteomyelitis were treated in the period from 1965-1982. Only patients who had been followed for two or more years of treatment were included in the series for evaluation. All foci were treated surgically with thorough debridement. According to the management of the wounds, patients were divided into three groups: wound healing by secondary intention in cases where skin closure was impossible; primary closure of wound with or without pedicle muscle transfer in cases of a small debrided cavity or in cases where a nearby skeletal muscle is available; and closed irrigation and suction drainage of the wound cavity. After a long-term follow-up period, satisfactory results to varying degrees were obtained in each group. Closed intermittent irrigation and suction drainage with high concentrations of antibiotic solutions gave the best results. In instances of failure, the causes may be due to inadequate removal of infected sclerotic bone and sequestra, obstruction of drainage tubes, resistance to antibiotics, or inadequate systemic antibiotic treatment. The use of myocutaneous flap transference to close the postoperative wound of chronic osteomyelitis was introduced, and preliminary results are encouraging.
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