[Effects of proteolytic enzymes on demineralization of enamel]

Papain, trypsin and collagenase were used in the experiment for the study of their effects on the demineralization of enamel surface by organic acids in vivo. No effect of any of the enzymes was observed. The use of papain and trypsin in treating tooth surfaces in vitro, no matter whether sodium bisulfite was used, showed no effect on the demineralization of the enamel by mixed organic acids. But, by the analysis of amino acids in the enzyme solutions before and after treating tooth surface, it was shown that some proteinous substances were destroyed. Accordingly, it can be suggested that the enzyme takes no part in the destruction of the inorganic tooth substance.

Control of rat glomerular epithelial cell growth in vitro

The interaction of cultured rat GEC1 with several growth factors was explored in order to obtain a better understanding of in vivo factors which might stimulate GEC proliferation. GEC proliferated in response to EGF but not IGF-1, MSA or PDGF. Specific, saturable receptors for EGF were detected in saturation and competition binding studies utilizing 125I-EGF with an approximate Kd of 1.7 nM and 86,000 binding sites per cell. TGF-beta inhibited GEC growth in a time and dose dependent manner with a brief early exposure resulting in prolonged growth inhibition which was not reversible by EGF. Exposure to TGF-beta sufficient to maximally inhibit growth had no effect on EGF binding to GEC. More prolonged exposure to TGF-beta, however, did result in an increase in the apparent number of EGF receptors on GEC but no change in Kd. These studies suggest that EGF and TGF-beta released by inflammatory cells or platelets during the course of glomerular injury may play a role in modulating glomerular cell proliferation.

[Biological characteristics of Psoralea corylifolia L]

A study has been made on the biological characteristics of Psoralea corylifolia under general cultivating conditions. To search for the laws of growth and development so as to facilitate further studies on the cultivating techniques for higher production of Psoralea corylifolia.

Anti-lipid peroxidation and protection of ginsenosides against cerebral ischemia-reperfusion injuries in rats

The correlation between protective effect of ginsenosides Rb + R0 and brain endogenously-derived prostacyclin synthesis, thromboxane A2 formation and lipid peroxidation were estimated in rats. Ginsenosides Rb + R0 100 mg/kg iv 30 min before 4-vessel occlusion elevated 6-keto-PGF1 alpha level, declined thromboxane B2 and brain edema formation, reduced the rise of lipid peroxides and suppressed the reduction in both creatine phosphokinase (CK) and superoxide dismutase (SOD) activities in brain tissue after 40-min ischemia followed by 1-h reperfusion. Furthermore, these improvements were partially abolished by pretreating with iv indomethacin. It is concluded that ginsenosides possess protective effect on cerebral ischemia-reperfusion injury of rats and ginsenosides Rb + R0 are the active principles. The underlying mechanism of protection is ascribed partially or mainly to the facilitated synthesis and release of prostacyclin, reduced formation of thromboxane A2 and inhibited generation of free radicals and subsequent lipid peroxidation.

[Effect of electro-acupuncture of zusanli on unit discharges in the lateral hypothalamic area induced by stomach distension]

Previous studies in our laboratory have shown that some unit discharges of the neurons in Feeding Centre of the lateral hypothalamic area (LHA) may be inhibited by distending stomach. The present study was performed to observe the effect of electro-acupuncture of "Zusanli" point on the discharge-inhibitory reaction induced by distending stomach in rats. Among 52 unit discharges observed, 36 (69.2%) showed that electro-acupuncturing "Zusanli" point abolished the inhibitory reaction induced by distending stomach. The durations of the effect range from 5 to 15 minutes. These results indicate that the somatic input from "Zusanli" plant may influence the reactivity of Feeding Centre of LHA to the activity of stomach.

[Types of left ventricular hypertrophy and their functional changes in essential hypertension]

104 patients of hypertensive left ventricular hypertrophy (LVH) were studied by two-dimensional echocardiography. According to the changes of left ventricular wall thickness, wall mass, end-diastolic volume and ejection fraction, they were divided into three types (concentric, dilated, disproportionate): (1) Concentric LVH 83 cases (79.8%) with thickened ventricular wall and augmented mass. (2) Dilated LVH 13 cases (12.5%) with left ventricular cavity enlarged and both ventricular mass and volume increased, ejection fraction decreased. (3) Disproportionate LVH 8 cases (7.7%), similar to hypertrophic cardiomyopathy with excess increase in interventricular septal thickness. The thickness ratio between interventricular septal and left ventricular posterior wall was greater than or equal to 1.3.

Captopril and ramiprilat protect against free radical injury in isolated working rat hearts

The protection of angiotensin converting enzyme (ACE) inhibitors, captopril and ramiprilat, against free radical-mediated myocardial injury were studied in isolated working rat hearts. Free radicals were generated by electrolysis of Krebs-Henseleit solution with 10 mA direct current for 1 min. Both captopril (360 mumol/l) and ramiprilat (12.5 mumol/l) significantly reduced the decrease of left ventricle dP/dt'max, coronary flow (CF), myocardial superoxide dismutase (SOD) and creatine kinase (CK) activities and the elevation of S-T segment of epicardial ECG as well as the rise of myocardial malondialdehyde (MDA) content caused by electrolysed perfusate. Captopril afforded a dose-dependent protection on cardiac functions with various concentrations of 45, 90, 180 and 360 mumol/l. Iloprost (30 nmol/l), a stable mimetic of prostacyclin, could also alleviate free radical-mediated myocardial injuries. All the beneficial effects of ramiprilat (12.5 mumol/l) were abolished by the administration of indomethacin (5 mumol). In contrast, captopril (90 mumol/l) still exhibited significant protective effects after indomethacin (9 mumol) was administered, though these protective effects were insignificantly weakened. In order to assess the role of sulfhydryl (-SH) group in the effects of captopril, a SH-containing drug S8 and a disulfide DG4, both are deficient in ACE inhibitory properties in vitro, were examined. Data showed that S8 (180 mumol/l) provided a significant protection while DG4 showed no protective effect. It is concluded that ACE inhibitors can protect against free radical-induced myocardial damage. Ramiprilat, a non-SH-containing ACE inhibitor, inhibits free radical-induced damages mainly by stimulation of prostacyclin synthesis and/or release. In addition to this effect, captopril, a SH-containing ACE inhibitor, may exert additional anti-free radical effects by a mechanism which is probably related to the sulfhydryl group.

Dental caries in adult and elderly Chinese

This paper reports on a study of dental caries conducted among 1744 urban and rural Chinese (from 20 to 80 years old), who were selected by means of a systematic stratified sampling procedure. The prevalence of one or more decayed or filled teeth ranged from 48 to 90% in urban residents, and from 51 to 97% in rural residents, depending on age. The mean number of decayed or filled teeth ranged from 1.2 (+/- 1.9) among 20-29-year-olds, to 6.2 (+/- 5.5) among 70+-year-olds, and was highest among rural residents. Among 20-29-year-olds, the main components of the DFT were enamel lesions and fillings. Among 30-49-year-olds, the DFT consisted mainly of enamel lesions and filled teeth, as well as teeth with lesions involving the pulpal tissues. In subjects over the age of 50 years, lesions involving pulpal tissues were the predominant type, followed by root-surface lesions. In subjects below the age of 50 years, most of the caries experience derived from coronal surfaces, particularly occlusal surfaces. Root-surface caries was predominantly a feature of persons aged 50 years and above. Despite a large number of surfaces being at risk of root-surface caries, less than 10% of the surfaces were so affected. Although cross-sectional in nature, these data indicate that when the oral hygiene standards are poor, caries lesions continue to develop and progress throughout life. With age, dental caries becomes a substantial oral health problem in this population of adult and elderly Chinese, despite the availability of some dental services.

Tooth mortality and prosthetic treatment patterns in urban and rural Chinese aged 20-80 years

The study describes tooth mortality levels and pattern of prosthetic treatments in a sample of 1744 Chinese aged 20-80 yr who are residents of Beijing area. Complete edentulousness was rarely seen before the age of 60 yr. Beyond this age up to 26% were edentulous, depending on age and sex. The mean number of teeth present ranged from 10.0 to 29.7 depending on age, sex, and area of residence. Below the age of 60 yr very few persons had experienced extensive loss of teeth but thereafter the number of teeth missing was substantially increased. Prosthetic treatments in the form of partial dentures, crowns, and bridges were frequently observed even in the younger age groups. In all age groups the number of teeth exhibiting caries lesions involving the pulp was much higher than the number of teeth exhibiting extensive mobility. Although many people retain a high number of teeth even late in life our findings indicate a substantial need for, in particular, relief of pain services. Concurrently, emphasis must be placed on preventive programs aiming at interfering with ongoing disease.

Novel arrangement of rRNA genes in Mycoplasma gallisepticum: separation of the 16S gene of one set from the 23S and 5S genes

Large restriction fragments from the DNA of Mycoplasma gallisepticum S6 and PG31, which were prepared by digestion with BglI, BssHII, SmaI, or XhoI and which were separated by pulsed-field electrophoresis, were hybridized with probes containing most, or different parts, of an rRNA operon of Mycoplasma capricolum. The results showed that the genomes contained three widely separated rRNA loci. One locus contained genes for all three rRNA species and another contained 23S and probably 5S rRNA genes, whereas the third appeared to have only a 16S rRNA gene.

[Pacemaker syndrome: a report of 6 cases]

Six patients suspected to have "pacemaker syndrome" were studied with hemodynamic and electrophysiologic methods. Symptoms appeared after implantation of ventricular pacemaker (VVI). Mile symptoms such as dizziness and fatigue and severe symptom of heart failure were noted. The results of the study suggested that cardiac output decreases due to loss of atrial contribution to ventricular filling and also as a result of increase of systemic venous pressure. If the patient has V-A conduction, cardiac output will decrease further. Restoration of atrioventricular synchronization is essential in the treatment of the pacemaker syndrome.

[Electrophysiologic study of concealed accessory A-V pathway]

The presence of concealed accessory A-V pathways (CAP) was demonstrated in 14 out of 18 (78%) patients with supraventricular tachycardia (SVT) and narrow QRS complexes. Such a high percentage of CAP mediated AVRT is a quite unique finding. The importance of a standard programmed electrical stimulation protocol in documenting CAP is emphasized. Careful atrial mapping and premature ventricular stimulation during SVT are very helpful for diagnosis and localization of CAP. We considered that a V-A interval of 75 ms or more on intracardiac electrogram or a R-P interval of 85 ms or more on esophageal electrogram is a good criterion for AVRT utilizing an accessory pathway.

Alterations in blood pressure of normotensive and hypertensive rats following intrathecal injections of neuropeptide Y

The effect of the intrathecal administration of neuropeptide Y (NPY) on blood pressure and heart rate of anesthetized normotensive and hypertensive rats was studied. Neuropeptide Y was observed to produce a decrease in the blood pressure of Sprague-Dawley, Wistar Kyoto (WKY), DOCA-salt, and DOCA-sham control rats. The maximum percent decrease in blood pressure of Sprague-Dawley rats was 12.8 and 15.2% in response to 0.1 and 1.0 nmol NPY, respectively. Similar changes in heart rate were observed. The depressor effect of intrathecal NPY was attenuated by prior treatment with yohimbine and propranolol but not prazosin. The depressor effect of intrathecal NPY observed in normotensive and DOCA-salt hypertensive rats was not seen in the spontaneously hypertensive rat (SHR). The studies extend to the spinal cord the list of regions and tissues where NPY can produce physiological effects. It is concluded that the effects of NPY are closely associated with sympathetic preganglionic neurons in the spinal cord that the depressor effect of NPY involves alpha 2 and beta adrenoceptors, and that a loss of the depressor effect of NPY may contribute to the development or maintenance of hypertension in the SHR.

Characterization of a potential source of barley yellow dwarf virus resistance for wheat

Resistance to barley yellow dwarf virus (BYDV) has been described in lines derived from crosses between wheat and Thinopyrum intermedium. The resistance in one such line, Zhong 4, originating in China, was expressed against two different serotypes of BYDV as measured by accumulation of virus in infected seedlings. F1 hybrids between wheat (2n = 42) and Zhong 4 (2n = 56) had 49 chromosomes and intermediate levels of virus when compared to the parent lines. Cytological and molecular hybridization studies suggested that the BYDV resistance in Zhong 4 is carried on a set of seven pairs of nonwheat chromosomes that derived from a combination of the E and X genomes present in Th. intermedium.Key words: Barley yellow dwarf virus, wheat, ribosomal DNA, Agropyron intermedium, Thinopyrum intermedium, virus resistance.