[Study on composition of plaque fluid in individuals with no oral hygiene]

OBJECTIVE

To study the change of composition in long-term plaque fluid after sucrose rinse and the cariogenicity of plaque.

METHODS

43 subjects, who had no regular oral hygiene and no tooth brushing at least for one year, were selected. According to their caries status, 27 as caries-free group and 16 as caries-positive group. Plaque were obtained before and at 7 minutes after a 10% sucrose rinse. Additionally, plaque samples of 15 and 30 minutes after sucrose rinse from 11 subjects were collected. The pH value and the concentrations of organic acids and inorganic ions in plaque fluid were measured.

RESULTS

At 7 minutes after sucrose rinse, pH and the concentration of ammonium were significantly decreased, and the concentrations of lactic acid and formic acid were significantly increased. All these changes were similar to those of short-term plaque. No significant difference with any single component of plaque fluid was found between caries-free group and caries-positive group, neither before sucrose rinse nor after sucrose rinse.

CONCLUSIONS

Changes of the composition in the plaque fluid were basically similar between long-term and short-term plaque, but single component in plaque fluid could not reflect the cariogenicity of plaque.

[A study on formation of N-(nitrosomethyl) urea in experimental pig stomach gavaged with fish sauce]

OBJECTIVE

To study formation of N-(nitrosomethyl) urea (NMU), which is categorized as N-nitrosamides -- a sort of strong chemical carcinogen, by perfusion with fish sauce via pig stomach fistula, which is used daily as cooking flavor by local residents in Changle County, Fujian Province, a highly-prevalent area for gastric cancer.

METHODS

Fistulization was performed in fasting experimental pigs' stomach, and their gastric juice was suctioned 30 minutes after perfusion with fish sauce and sodium nitrite via fistula. Gastric juice specimen was purified and concentrated and determined for NMU with high performance liquid chromatography-photolysis pyrolysis-thermal energy analyzer.

RESULTS

NMU was detected in the pig stomach at pH 1 - 2, where NMU formed. Formation of NMU depended on the amount of nitrite added in a dose-dependent relationship. Level of NMU in gastric juice reached 25.4 and 7.97 micromol/L, respectively, when 3.48 and 0.87 mmol of sodium nitrite were fed into the stomach. No NMU could be detected, as 0.22 mmol of sodium nitrite fed.

CONCLUSION

Under the condition of pH 1 - 2 and presence of sodium nitrite, NMU was synthesized in the stomachs of experimental pigs fed with fish sauce via gastric fistula. It is postulated that N-nitrosamides, such as NMU could be formed endogenously in the stomachs of local residents who consume fish sauce often and have a higher exposure to nitrite in their stomachs.

Diabetes-induced vascular dysfunction in the retina: role of endothelins

AIMS/HYPOTHESIS

Vasoactive factors like endothelins, by virtue of the microvascular regulation as well as by other effects, possibly play important parts in the pathogenesis of diabetic retinal microangiopathy. We investigated retinal vascular dysfunction in streptozotocin-induced diabetes and its relation with endothelins in short- and long-term diabetes.

METHODS

Diabetic rats with or without an endothelin receptor antagonist (bosentan) treatment were investigated after 1 month and 6 months of follow-up. Retinal blood flow was measured and compared with age- and sex-matched non-diabetic control animals. Retinal tissues were analysed for endothelin-1, endothelin-3, endothelin A and endothelin B mRNA. Distribution of endothelin-1 and endothelin-3 was investigated by immunocytochemistry and that for endothelin receptors by ligand binding and autoradiography.

RESULTS

Diabetic animals showed hyperglycaemia, glycosuria, elevated glycated haemoglobin values and reduced body weight gain. Retinal blood flow showed an increased resistivity index, an indicator of vasoconstriction, after 1 month of diabetes which was prevented by treatment with bosentan. This functional change in diabetes was eliminated after 6 months of follow-up. The retina from the diabetic animals showed increased mRNA expression for endothelin-1, endothelin-3 and endothelin A after one month. In addition, endothelin B mRNA expression was increased after 6 months. Furthermore, endothelin-1 and endothelin-3 immunoreactivity and endothelin receptor concentrations were increased in the retina of diabetic rats.

CONCLUSION/INTERPRETATION

The results from this study indicate that the endothelin system is of importance in mediating retinal changes in diabetes although mechanisms of the endothelin system alteration as well as their effects might vary depending on the duration of diabetes. [Diabetologia (1999) 42: 1228-1234]

Corneal topographical changes following strabismus surgery

PURPOSE

To study corneal topographical changes after strabismus surgery.

METHODS

Computer-aided corneal topography was used in 43 strabismus patients (45 eyes) one or two days prior to and six or seven days after strabismus surgery. The spherical and cylindrical equivalents were calculated based on the simulated keratometry.

RESULTS

After the surgery, only the changes at 3 mm in the inferior quadrant were statistically significant. The changes at 3 mm in the rest quadrants and the changes at 7 mm were not significant. Significant changes in spherical equivalent were found post-operatively. Neither the horizontal nor the vertical meridional equivalent showed significant changes after surgery.

CONCLUSIONS

The results of corneal topographical changes following strabismus surgery in our preliminary study indicated the little effect of strabismus surgery on corneal curvature and corneal astigmatism.

Chromogranin A in the central nervous system of the rat: pan-neuronal expression of its mRNA and selective expression of the protein

Chromogranin A, a glycoprotein stored in secretory granules of neuroendocrine cells, displays a widespread distribution throughout the central nervous system of a variety of species. In situ hybridization histochemistry was employed to investigate the localization of chromogranin A mRNA in the central nervous system of the rat. The previously characterized monoclonal antibody, LK2H-10, was employed in an immunohistochemical study to compare the topographic localization of the chromogranin A protein with that of its mRNA. Although the latter, as revealed by in situ hybridization, displayed a ubiquitous, pan-neuronal localization throughout the rat brain, LK2H-10 immunoreactive cell bodies and axon terminals were disposed in a widespread, but highly regionally differential, distribution. This discrepancy suggests that chromogranin A is processed in a regionally differential fashion in the rat brain to yield one or multiple variant forms, one of which is specifically recognized by LK2H-10. Catecholaminergic cell groups consistently displayed LK2H-10 immunoreactivity. LK2H-10 immunopositive axon terminals were prominent in the circumventricular organs. In addition, LK2H-10 immunoreactivity was also detected in a subset of astrocytes which demonstrated a widespread, but anatomically restricted, pattern of distribution. Consequently, the variant of chromogranin A labelled by LK2H-10 represents a novel neurochemical marker for regionally differential astrocytic diversity.

Parathyroid hormone-related proteins is abundant in osteoarthritic cartilage, and the parathyroid hormone-related protein 1-173 isoform is selectively induced by transforming growth factor beta in articular chondrocytes and suppresses generation of extracellular inorganic pyrophosphate

OBJECTIVE

Parathyroid hormone-related protein (PTHrP) is a major, locally expressed regulator of growth cartilage chondrocyte proliferation, differentiation, synthetic function, and mineralization. Because mechanisms that limit cartilage chondrocytes from maturing and mineralizing are diminished in osteoarthritis (OA), we studied PTHrP expression by articular chondrocytes.

METHODS

PTHrP was studied in normal knee cartilage samples and cultured articular chondrocytes, and in cartilage specimens from knees with advanced OA, obtained at the time of joint replacement.

RESULTS

PTHrP was more abundant in OA than in normal human knee articular cartilage. Both demonstrated PTH/PTHrP receptor expression. PTHrP 1-173, one of three alternatively spliced PTHrP isoforms, was exclusively expressed and induced by transforming growth factor beta in cultured chondrocytes. Chondrocytes mainly used the GC-rich P2 alternative promoter to express PTHrP messenger RNA. Inhibition by PTHrP 1-173, but not by PTHrP 1-146 or PTHrP 1-87, of inorganic pyrophosphate (PPi) elaboration suggested selective functional properties of the 1-173 isoform. Exposure to a neutralizing antibody to PTHrP increased PPi elaboration by articular chondrocytes.

CONCLUSION

Increased expression of PTHrP, including the 1-173 isoform, has the potential to contribute to the pathologic differentiated functions of chondrocytes, including mineralization, in OA.

[The influence of implantal autograft bone in total cleft palate on maxillary growth an experiment study in dogs]

OBJECTIVE

To test the hypothesis that implant autograft bone in total cleft palate at primary cleft palate repair which may resists the disturbance of maxillary growth by cleft and denud bony wound.

METHODS

40 dogs were randomly divided into four groups: three control groups and one experimental group. The first control group was unoperated, the second group had a surgically created cleft plate, the third group also had a surgically created cleft palate. Using a two-flap procedure immidiately, the experiment group had a surgically created cleft palate, but the palate was recontracted by implanting a piece of autograft rib bone with two-flap repair. All animals were sacrificed on the 34th week after operation (43 weeks postnatal). Thirty-four metricranial variables were measured directy from the cleaned skulls.

RESULTS

The method is useful for maxillary growth and development by bone implant in total cleft palate, but it can cause maxillary deformity.

CONCLUSION

Clinical doctors should be cautious in using the method of primary-delay bone grafting in reparing total cleft of cleft palate.

Characterization of N-(Nitrosomethyl)urea in Nitrosated Fermented Fish Products

To characterize chemical carcinogens in acidic-nitrosated fish sauce sample, N-nitrosamides in the sample were separated by two kinds of reversed-phase HPLC columns, and with detection by photolysis-pyrolysis-thermal energy analyzer. A strong chromatographic peak at t(R) 12 or 4.5 min, same as that for N-(nitrosomethyl)urea (NMU), was obtained on PRP-1 or C(18) HPLC column from fish sauce sample with 10 mM trifluoroacetic acid as the basic mobile; acetonitrile, as organic modifier after the sample was nitrosated by 5 mmol/L of sodium nitrite (final concentration) at 37 degrees C and pH 2.0 for 1 h. No response above t(R) could be observed from the nitrosated sample in the detection system without photolysis. Such a peak could not be obtained from the unnitrosated fish sauce either. These results indicated that the component was NMU. Furthermore, this component, NMU, could also be detected in the nitrosated human gastric juice sample spiked with fish sauce. The formation of NMU in the sample was pH- and nitrite-dependent. This paper provides direct evidence that NMU formation could occur in fish sauce from the high-risk area for stomach cancer and in the fish sauce spiked human gastric juice during nitrosation under simulated gastric conditions.

[A study of human papillomavirus infection during pregnancy and transmission of virus to fetus]

To study the human papillomavirus (HPV) infection during pregnancy and transmission of virus to fetus, samples such as, cervical secretion, peripheral blood, amniotic fluid, neonatal umbilical blood from 96 women with normal pregnancy were screened for HPV DNA by polymerase chain reaction (PCR), and HPV DNA in condyloma acuminata tissues, amniotic fluid of 31 pregnant women were detected by PCR as well. The results showed HPV DNA positive rate of condyloma acuminata tissues was 92.32%, of cervical secretion in normal pregnant group, was 35.71%, of peripheral blood was 57.69%. The HPV DNA maternal-fetus transmission rate was 44.44%, the transmission rate via placenta was 60%. It is concluded that HPV DNA can be found not only in condyloma acuminata tissues, but also in genital tract, peripheral blood of pregnant women, Besides the transmission route of genital tract, there is also the blood-placenta route.

[An experimental study of the growth pattern and mechanisms of surgically induced cleft palate and palatoplasty on maxillary growth in dogs]

The authors observed the changing process of length, width and height of maxillary growth in experimental animals, the experimental animals were divided into the unoperated control group, the surgical induced cleft palate group, the repaired cleft palate group and the group of implanted autograft bone in total hard palate. The method of a serial dorsoventral and lateral cephalograms were used in the study. The experimental result showed: the rate of maxillary growth began to change from two to four weeks and finished in the eighteenth week after operation. There was a remarkable different rate of maxillary growth among the four groups. The track of premaxillary growth had a difference between unoperated control group and the others. The experimental result suggested that the direction of growth in nasal septal cartilage and the conduction of force from premaxillary to maxillary were inhibited. It is a main reason for maxillary growth disturbance of the cleft palate who had or had not surgery.

[An experimental study of the influence and mechanism of surgically induced cleft palate and palatoplasty on teeth and dental arch in dogs]

The dogs were selected as the experimental subjects in this study. The authors continuously observed the maxillary teeth and dental arch form in preoperation and 2, 4, 6, 10, 14, 18, 22, 26, 30, 34 weeks of post operation to all the animals. 40 puppies were divided into four groups, which were unoperated control group, surgically induced cleft palate group, cleft palate repaired group and cleft palate implanted bone group. The experimental result showed: there were remarkable differences at rate of itself growth between deciduous dentition and permanent dentition in the four groups. The result suggested that the cleft palate was a reason for disturbances of dental arch development, an exposed bone wound in hard palate of maxillary after palatoplasty was an important reason that it made maxillary dental arch growth problem heavier, authors could prevent the disturbs the transverse development of the maxillary dental arch from cleft palate who had or had not repaired by implanted bone in total cleft palate.

Kilohertz femtosecond UV-pumped visible beta-barium borate and lithium triborate optical parametric generator and amplifier

We demonstrate optical parametric generation and amplification of femtosecond pulses in the entire visible range using type-I phase-matched beta-barium borate and lithium triborate crystals pumped by the frequency-doubled output of a Ti:sapphire regenerative amplifier at 395 nm. The output is tunable from 470 to 770 nm with a pulse width of ~170 fs at a repetition rate of 1 kHz and a maximum output energy of ~1.1 muJ/pulse. The visible optical parametric amplifier output was then frequency doubled and sum frequency mixed with the fundamental output of Ti:sapphire at 790 nm to produce UV pulses with a conversion efficiency of greater than 25%. The second harmonic generated UV pulses are tunable from 240 to 380 nm with a maximum pulse energy of ~260 nJ/pulse.

[Comparison of total N-nitrosamides in fasting gastric juice from subjects in high and low risk areas for gastric cancer]

OBJECTIVE

The status of human exposure to N-nitrosamides (NAD) is almost unknown, although they are probably carcinogenic to human stomach. This study is to elucidate the relationship between NAD exposure and causes of gastric carcinomas (GC).

METHODS

The total amount of natural NAD was detected with a photohydrolysis-TEA method (184 nmole/l, detection limit) in fasting gastric juice samples from subjects aged 35-68 by fibroendoscope both in a high and low risk area for GC with the same geographical and socioeconomic conditions in Shangdon Province, China.

RESULTS

A) More NAD-positive samples in the high risk area (Linqu County, n = 176) were observed than in the low risk area (Chongshan County, n = 99), the difference was significantly after age-adjustment (40.9% vs. 30.3%, P = 0.0324). B)84% of samples was pH < or = 3 in Chongshan, whereas only 48% in Linqu (P < 0.001). In the acidic samples more NAD-positive ones in Linqu were found than in Chongshan (46.2% vs 27.4%, P < 0.01). NAD-positive rate was higher in samples with pH > or = 5 than those with pH < or = 3 only in the low but not in the high risk area. C)NAD-positive rate was also higher in samples from subjects with chronic atrophic gastritis (CAG) with or without dysplasia than those from normal subjects and from those with superficial gastritis or CAG with intestinal metaplasia both in the high and low risk areas.

CONCLUSION

The results suggest that human endogenous exposure to NAD in the high risk area for GC be higher than that in the low risk area; CAG and dysplasia may play a role in human gastric carcinogenesis by N-nitrosamides.

[Observation of compensatory head posture in superior oblique muscle paralysis]

PURPOSE

Superior oblique muscle paralysis is the most common disease in clinic. We analysed the cause, machanism and regularity of compensatory head posture in superior oblique muscle paralysis.

METHODS

All of 27 cases with superior oblique muscle paralysis aere examined regularly, and special muscle, binocular single vision function with synoptophore examined. Bielschowsky test was made.

RESULTS

In our cases, the incidence rate of compensatory head posture was 40.7%, which had relations with age when a patient had disease, period and function of binocular single vision.

CONCLUSION

The existance of binocular single vision function is the physiological bases leading to compensatory head posture, and the patients whose ages are older than 3 years and the course is less than 10 years may present the compensatory head posture. So we should pay attention to early diagnosis and training to restore the binocular single vision function.

[Synthesis and positive inotropic activity of 3,4-dimethoxybenzoyl-piperazine derivatives]

We designed and synthesized twelve new 3,4-dimethoxybenzoyl-piperazine derivatives. These chemical structures (TM-1-TM-12) were confirmed by means of IR, MS, H-NMR and elemental analysis. Compounds (OPC-8212 TM-1, TM-2, VPA) were tested for positive inotropic activity. The results showed that compounds OPC-8212 and VPA possessed positive inotropic activity (P < 0.05). Further pharmacological studies will be made.

[Preliminary studies on microbe-mediated N-nitrosamide synthesis]

Chemical synthesis of N-nitrosamide and influences on it by bacteria and fungi isolated from human gastric juice were studied with trace analysis method to explore the pathway of its endogenous formation. Results showed in synthesis of N-methyl-N-nitrosourea (MNU) with precursors of methylurea (0.42 mmol/L) and sodium nitrite (25 mmol/L) in a condition simulating human stomach, pH of the reaction system played an important role in the synthesis, the amount of synthetic chemical maximized at a pH of 1-3 and almost no synthesis was found at pH of 5-7. A study on the ability to synthesize MNU catalyzed by bacteria isolated from the patients with stomach cancer living in a high-risk area showed its synthesis could be accelerated by Pseudomonas aeruginosa at pH of 6-7 with its catalyzing activity existed in heat liable component of living bacteria. This is the first report showing microorganisms to catalyze the formation of N-nitrosamide from its precursors.

Social aspects of malaria in Heping, Hainan

This paper presents findings from a study conducted in Heping Town, Qiongzhong County, Hainan Province, China. The study, conducted in 1992, used qualitative as well as quantitative methods to gather social, cultural and behavioural data associated with the acquisition, transmission and prevention of malaria, and the diagnosis and treatment of disease. These methods included focus groups, key informant and other in-depth interviews, and observations, a household survey and tests of school children of knowledge of malaria. The study is among the first to our knowledge that has utilized this broad mix of methods for tropical disease research in China.

[A study on the degradation kinetics of nicotinamide powder]

The effect of temperature and humidity on the degradation of nicotinamide powder was studied below the critical relative humidity at temperatures 50-80 degrees C and relative humidities 50-80%. The rate equation of the degradation of nicotinamide under isothermal and constant humidity conditions is -dC/dt=k(Co-C)-1, where k is the apparent rate constant of degradation, Co and C are initial concentration and concentration at time t of nicotinamide, respectively. The relationship between the apparent rate constant of degradation and relative humidity RH is in K=a + m (RH), where a and m are constants. When RH are 50.35, 66.85, 75.33 and 80.35%, the apparent activation energies of degradation from Arrhenius equation are 219.94, 181.86, 168.99 and 153.89 kJ/mol, respectively. The rate equation the photodegradation of nicotinamide under room temperature is -dR/dt=K' (Ro-R)-1, where K' is the apparent rate constant of photodegradation, Ro and R are initial reflectance and reflectance at time t of nicotinamide, respectively.

[A study on pathogen antigen and serodiagnosis of Malleus and Melioidosis with McAbs]

A study on pathogen antigen and serodiagnosis of Malleus and Mlioidosis was made with McAbs which are against Ps. mallei or Ps. pseudomallei. The results showed that (1) Ps. mallei and Ps. pseudomallei express different surface antigen types respectively, and there are antigen overlapping in some degree between them; (2) Epitope 2D4 is common to Ps. mallei and Ps. pseudomallei; (3) The antibody which is similar to McAbs 4D4 or 1A9 might be a common serum antibody of Malleus and Melioidosis; and (4) McAb 3A1 is a high specific one which reacts with Ps. pseudomallei only, and with it, it is possible to resolve the immunological problem of distinguishing diagnosis between Malleus and Melioidosis.

Highly efficient ultraviolet generation at 355 nm in LiB(3)O(5)

Highly efficient generation of UV radiation at 355 nm has been achieved in a LiB(3)O(5) crystal through the frequency mixing of the fundamental and second-harmonic radiation of a Nd:YAG laser. An energy conversion efficiency of 60% has been obtained under the experimental conditions described here. Thus the usefulness of LiB(3)O(5) for frequency-conversion applications is demonstrated.