Study of stabilizing CaF2:Dy ultraviolet sensitivity by double annealing treatment

The intrinsic thermoluminescent response to ultraviolet radiation of CaF2:Dy phosphor is enhanced by pre-irradiation high-temperature annealing treatment. The thermoluminescent response is stabilized by adding a medium temperature annealing treatment after the previous annealing. The experimental results show that the annealing treatment of 1 h 850 degrees C high-temperature annealing followed by 1 h 350 degrees C medium-temperature annealing is the optimum treatment to have high thermoluminescent response and good stability. The results also show that (1) the thermoluminescent response to 253.7 nm ultraviolet radiation is increased and stabilized, (2) the thermoluminescent sensitivity and glow curve distribution to 235.7 nm ultraviolet radiation are retained, and (3) the thermoluminescent response to 253.7 nm ultraviolet is linear from 3 to 1 x 10(3) Jm(-2), but there is no linear response with respect to 365 nm ultraviolet.

Hydrogen peroxide induces premature acrosome reaction in rat sperm and reduces their penetration of the zona pellucida

Recent studies have demonstrated that mammalian sperm are capable of generating reactive oxygen species (ROS) and that this activity is significantly accelerated in subfertile subjects. The observed decrease in penetration of zona-intact oocyte might be explained by chemical-induced ROS-related early onset of capacitation and premature acrosome reaction, but the mechanism is not clear. We determine whether zona-intact oocyte penetration capability in rat epididymal sperm was affected by premature acrosome reaction in rat sperm treated with hydrogen peroxide (H2O2) and calcium ionophore A23187 or H2O2 and lysophosphatidyl choline. Chlortetracycline fluorescence assay was used to study the status of acrosome reaction on epididymal sperm. The sperm-oocyte binding and penetration assay was used to evaluate the capability for zona pellucida penetration. There was a positive linear correlation between the frequency of acrosome-reacted sperm and capability of sperm-oocyte binding and penetration in zona-free oocytes. In the zona-intact oocytes, the sperm-oocyte penetration rate was suppressed as the proportions of acrosome-reacted sperm increased. In summary, this study showed that premature acrosome reaction reduced rat sperm's capability of penetrating zona-intact oocytes. However, this reduction is not seen in zona-free oocytes. These findings may provide a basis for understanding the effects of sperm ROS generation on zona pellucida penetration in male reproductive toxicology.

Lead-induced changes in spermatozoa function and metabolism

The relationships between sperm reactive oxygen species (ROS) generation, the capacitation process and acrosome reaction, and the spermoocyte penetration rate (SOPR) were investigated to understand the effect of lead toxicity on sperm functions and the mechanisms of these effects. Male Sprague-Dawley rats received weekly intraperitoneal injections of 20 mg or 50 mg lead acetate/kg or 20 mg or 50 mg sodium acetate/kg (control) for 6 wk. Serum testosterone was measured by radioimmunoassay. In cauda epididymal spermatozoa, the chemiluminescence was measured to evaluate the sperm ROS generation. Chlortetracycline fluorescence assay was used to study the status of capacitation and acrosome reaction on fresh cauda epididymal spermatozoa and after 2, 4, or 24 h of incubation with 5 mg/ml bovine serum albumin. In lead-exposed rats, the serum testosterone levels were reduced, and the percentage of capacitation and the chemiluminescence were significantly increased in fresh cauda epididymal spermatozoa. The serum testosterone levels were negatively associated with the percentage of acrosome-reacted spermatozoa. Sperm chemiluminescence was positively correlated with the percentage of both capacitated and acrosome-reacted spermatozoa. The SOPR was negatively associated with the percentage of both capacitated and acrosome-reacted spermatozoa. In summary, this study showed that male rats exposed to lead had decreased serum testosterone levels and that this metal produced early onset of capacitation by one of the pathways of ROS generation. These effects might consequently result in premature acrosome reaction and reduced zona-intact oocyte-penetrating capability.

Effects of vitamin E and/or C on reactive oxygen species-related lead toxicity in the rat sperm

This study was undertaken to investigate whether treatment with vitamin E (VE) and/or vitamin C (VC) protects rat sperm by inhibiting reactive oxygen species generation induced by lead (Pb) exposure. Male Sprague-Dawley rats were assigned to the following five groups: vitamin-unsupplemented; 150 mg VE/kg chow supplemented; 300 mg VE/kg chow supplemented; 500 mg VC/l drinking water supplemented and 150 mg VE/kg chow + 500 mg VC/l drinking water supplemented group. Rats in each group were divided into Pb-unexposed and Pb-exposed subgroups, received weekly intraperitoneal injection of 10 mg sodium acetate or 10 mg Pb acetate/kg for 6 weeks, respectively. The blood and sperm Pb levels were analyzed by graphite furnace atomic absorption spectrophotometer. Chemiluminescence was measured to evaluate the generation of sperm reactive oxygen species (ROS). Motility and sperm-oocyte penetration rate (SOPR) were measured. In Pb-unexposed rats, epididymal sperm counts, motility, ROS, and SOPR were not different in the five supplemented groups. Lead exposure might decrease the defense capacity of sperm to the oxidative stress and therefore elevate the ROS generation, reduce sperm motility, and reduce SOPR. Supplementation with VE and/or VC reduced ROS generation, prevented loss of motility and capacity of oocyte penetration in Pb-exposed rats. This study suggests that supplementation with VE and/or VC inhibits Pb-related ROS generation, protects spermatozoa from loss of motility and oocyte penetration capability.

Lead exposure causes generation of reactive oxygen species and functional impairment in rat sperm

The relationships between blood lead, sperm lead, sperm reactive oxygen species (ROS) level, and sperm fertile capability were investigated to understand the effects of lead exposure on sperm function and the mechanism of these effects. Male Sprague-Dawley rats, 7 weeks old, were randomly divided into control group and lead-treated group. The controls and lead-treated animals received intraperitoneal injection of 10 mg sodium acetate and 10 mg lead acetate/kg body weight, respectively, weekly for 6 or 9 weeks. The blood lead and epididymal sperm lead were analyzed by graphite furnace atomic absorption spectrophotometer. Chemiluminescence was measured to evaluate the generation of sperm ROS. Sperm-oocyte penetration rate (SOPR) was measured to evaluate sperm function. After 6 weeks of lead exposure, the rats had average blood lead levels of 32 microg/dl, sperm lead levels of 0.67 +/- 0.11 microg/10(9) sperm, unchanged epididymal sperm counts, percent of motile sperms, and motile epididymal sperm counts compared with control animals. However, after 9 weeks of lead exposure, the rats had average blood lead levels of 48.0 +/- 4.3 microg/dl, sperm lead levels of 0.88 +/- 0.16 microg/10(9) sperm, statistically lower epididymal sperm counts, and lower motile epididymal sperm counts. There was a good correlation between the blood lead and sperm lead(r2 = 0.946, P < 0.001). The sperms of lead-exposed rats produced significantly higher counts ofchemiluminescence than did those from the control rats (P < 0.001). The chemiluminescence counts were positively associated with sperm lead level (r2 = 0.613, P < 0.001). Epididymal sperm counts, motility and motile epididymal sperm counts were negatively associated with sperm chemiluminescence (r2 = 0.255, 0.152, and 0.299; P < 0.01, 0.05, and 0.01, respectively). The SOPR were positively associated with epididymal sperm counts, motility and motile epididymal sperm counts (r2 = 0.136, 0.285, and 0.264; P < 0.05, 0.01, and 0.001, respectively). The sperm chemiluminescence was negatively associated with SOPR (r2 = 0.519, P < 0.001). It is concluded that lead exposure probably affected the sperm function by activating one of the pathways of ROS generation.

Measurement of the radiation doses absorbed by jaw bones during irradiation of nasopharyngeal cancers

BACKGROUND

Nasopharyngeal carcinoma (NPC) occurs more frequently for Chinese than for other ethnic groups. The most common treatment for NPC is radiotherapy, but there is no report of the doses of radiation absorbed by the mandibular and maxillary bones, although exposure to radiation is one of the most important references for those patients who need to have oral surgical treatments.

METHODS

Thermoluminescent dosimeter (TLD) was used to measure radiation absorbed by a rando phantom and cancer patients.

RESULTS

The results showed that the doses absorbed by the mandible and maxilla depend on the dose applied, field size, and field shape. In the rando phantom, the range of absorption in the mandible was, for the central incisor 1.89-3.36 Gy, canine 1.96-3.78 Gy, bicuspid 2.24-14.14 Gy, second molar 4.34-31.92 Gy, internal pterygoid muscle region 70 Gy. In the maxilla the range was, for the central incisor 2.17-2.94 Gy, canine 2.24-3.36 Gy, bicuspid 3.15-4.41 Gy, second molar 7.00-7.42 Gy. In nasopharyngeal carcinoma patients, the mean radiation absorbed by the bicuspid vestibular region of the mandible was 3.09 Gy, by the bicuspid vestibule of the maxilla 3.35 Gy and by the midline vestibule 2.31 Gy. The radiation doses absorbed by maxilla and mandible from the incisor to the second premolars were less than 20% of the dose to the primary tumor.

CONCLUSIONS

The doses absorbed by the mandible and maxilla are relatively low in NPC patients receiving radiation therapy.

Role of oxidative DNA damage in hydroxychavicol-induced genotoxicity

Chewing betel quid has been linked to the development of oral cancer. In Taiwan, fresh Piper betle inflorescence is uniquely added to betel quid, and hydroxychavicol is the major phenolic components of P.betle inflorescence. In this study, we tested the mutagenic potential of hydroxychavicol in Salmonella typhimurium TA97, TA98, TA100 and TA102 with and without Aroclor-1254 induced S9 fraction. The results showed that hydroxychavicol was positive in S.typhimurium TA102 without metabolic activation. This increase in revertants was partially inhibited by catalase and superoxide dismutase. In Chinese hamster ovary (CHO-K1) cells, hydroxychavicol induced chromosome aberrations in a dose-dependent manner (10-50 microM) and the majority were chromosome-type aberrations. Hydroxychavicol also significantly increased the frequency of micronuclei in CHO-K1 cells up to 3-fold at a concentration of 40 microM. In addition, hydroxychavicol dose-dependently (0.1-20 microM) induced copper-dependent strand breaks in plasmid DNA. We further tested the oxidative DNA damage potential of hydroxychavicol by measuring 8-hydroxydeoxyguanosine (8-OH-dG) formation in CHO-K1 cells following an 18-h incubation and found that hydroxychavicol (6.25-100 microM) induced 8-OH-dG levels dose-dependently. The increase of 8-OH-dG formation was positively correlated (r = 0.79) with the hydroxychavicol-induced cytotoxicity. In conclusion, hydroxychavicol may exert its genotoxic potential through oxidative DNA damage.

Arrhythmias after cardioverter-defibrillator implantation: comparison of epicardial and transvenous systems

Surgery for implantable cardioverter-defibrillators can cause postoperative exacerbation of ventricular and atrial arrhythmias. It is not known whether the techniques of electrode implantation (epicardial vs transvenous) influence the incidence of arrhythmia exacerbation. We reviewed the postoperative course of 229 consecutive patients who received either epicardial (n = 119) or transvenous (n = 110) implantations from 1984 to 1994. Exacerbation of ventricular tachycardia (VT) was defined as an increase in the number of sustained VTs during the postoperative versus the preoperative 2 weeks. Of the entire cohort, 18 patients (8%) developed exacerbation of VT after operation, which was more frequent in patients with epicardial than with transvenous implantations (12% vs 4%, p < 0.03, odds ratio 3.5, 95% confidence interval 1.0 to 13.2). New-onset atrial fibrillation occurred in 15% of patients with epicardial versus 1% of those with transvenous implantations (p = 0.00005, odds ratio 19.4, 95% confidence interval 2.7 to 86.7). These differences persisted after excluding patients with concurrent cardiac surgery. Preoperative occurrence of arrhythmias was the strongest independent predictor for postoperative occurrence (p < 0.01 for VT, p < 0.0001 for atrial fibrillation). Epicardial implantation (p = 0.03) and a history of myocardial infarction (p = 0.04) were independent predictors for postoperative VT exacerbation, whereas epicardial implantation (p < 0.05) and concurrent coronary bypass surgery (p = 0.0001) were independent predictors for postoperative new atrial fibrillation. Perioperative discontinuation of antiarrhythmic drugs did not influence postoperative VT exacerbation. Epicardial implantation was associated with longer length of hospital stay than transvenous implantation (p = 0.0005), independent of age, left ventricular ejection fraction, and concurrent cardiac surgery.

[An investigation of radiation exposure on pediatric patients and doctors during cardiac catheterization and cineangiography]

Cardiac catheterization and cineangiography are invasive diagnostic radiological examinations which exposure the patient to a relatively high radiation dose, the largest radiation dose of any diagnostic examination. Sixty-one infants and children, aged 28 days to 15 years, were randomly selected into this study to assess such questions regarding cardiac catheterization in children as; (1) How much the pediatric patient's and doctor's radiation exposure is during a routine cardiac catheterization and cineangiography? (2) What difference are there in exposure to various areas of the body? (3) How much radiation exposure is related to cineangiography compared with fluoroscopy? (4) How much radiation exposure may be reduced by lead apron worn by doctors? Thermoluminescent dosimeters containing 80 mg of CaSO4: Dy were applied to the body for the measurement of radiation exposure during cardiac catheterization. In hemodynamic assessment of catheterization (mean time 6 +/- 5 min), dosimeters were placed on various areas of the patient's skin and unexposed dosimeters were attached to mid sternum and right lateral chest during cineangiography (mean time 11 +/- 5 sec). Average skin doses over the patients' organs during catheterization and cineangiography were: eye 51 mu Gy, thyroid 746 mu Gy, sternum 5,102 mu Gy, right lateral chest 10,098 mu Gy, umbilicus 123 mu Gy and gonad 24 mu Gy. The radiation exposure during cineangiography at sternum and right lateral chest contributed to 61% and 70% of total exposure.(ABSTRACT TRUNCATED AT 250 WORDS)

Radiation exposure of pediatric patients and physicians during cardiac catheterization and balloon pulmonary valvuloplasty

Thermoluminescent dosimeters were applied to various areas of 61 pediatric patients and physicians to measure radiation doses during routine cardiac catheterization and during 4 cases of balloon pulmonary valvuloplasty. Radiation doses were measured during chest roentgenography, fluoroscopy and cineangiography. Average skin dose to the chest was 121 microGy during chest x-ray, 5,182 microGy during catheterization and 641 mGy during valvuloplasty. For the eyes, thyroid and gonads of the patients, the exposure during routine catheterization was equal to 0.4, 6 and 0.2 chest x-rays, respectively. Radiation dose of the operator was 3 microGy for the eyes and 6 miCroGy in the thyroid. About 56% of the operator's dose could be reduced by thyroid shields, and 80% by lead aprons. The assistant received only 1 microGy outside the thyroid shield. Therefore, we have concluded that the patients' dose during routine catheterization is largely based on our experimental results, but the dose is acceptable based on the risk factor analysis. The skin dose to the right lateral chest of the patient during valvuloplasty is extremely high, perhaps as high as the equivalent of 1,000 chest x-rays. Besides the clinical benefits of valvuloplasty, the long-term radiation-related hazards to the patient should be carefully monitored.

Gonadal dose measurement in diagnostic nuclear medicine using thermoluminescent dosimeters

Instead of using the Medical Internal Radiation Dose Committee (MIRD) concept to calculate the gonadal dose during diagnostic examination using radiopharmaceuticals, measurements of gonadal doses using thermoluminescent dosimeters were studied. The results obtained are comparable with that calculated using the MIRD concept. Five frequently used examinations were investigated, viz., liver, brain, thyroid, bone scintigraphy and cholescintigraphy. The calibration of thermoluminescent dosimeters are fully described, and the experimental techniques are also fully presented.

A theoretical study of the effect of vitreous hemorrhage on the electroretinogram

A bioelectric field model of the electroretinogram was utilized to help determine whether the presence of blood in the vitreous could alter its electrical conductivity enough to attenuate what would have been a normal ERG. The electrical conductivities of the structures of the eye and the frequency content of the ERG were incorporated in the model. The result was that the vitreous conductivity would have to be reduced to a value below that of whole blood in order for the ERG to be significantly reduced. A reduced ERG would be due to another cause(s) and might preclude vitrectomy. According to this model, blood in the vitreous has no significant effect on conduction of the ERG to the cornea.

Red marrow dose measurement in phantom for tele-irradiation of the nasopharynx by cobalt-60 unit

This investigation is to study red marrow dose measurement for the 60Co gamma-ray treatment of nasopharyngeal carcinoma with the aid of Rando phantom. The energy of scattered radiation in space and in tissue was investigated by means of half-value layers with thermoluminescent dosimeters. Other related factors such as field size, SSD, and orientation of primary beams were also investigated. In the non-metastases cases, the red marrow dose is 26 +/- 6 rads which is about 0.40% tumor dose excluding the marrow at the NPC site. For the metastases cases, the red marrow dose is still about 0.40% tumor dose. If the red marrow at the NPC site is included, the red marrow dose is about 14.5% tumor dose for both non-metastases and metastases cases.

Erythromycin and clindamycin resistance in Corynebacterium diphtheriae from skin lesions

Erythromycin- and clindamycin-resistant Corynebacterium diphtheriae isolates were recovered from skin lesions. Resistance to erythromycin and clindamycin was induced by a subinhibitory concentration (0.03 microgram/ml) of erythromycin. Clindamycin (0.07 microgram/ml) was a more effective inducer of its own resistance than of erythromycin resistance. Erythromycin-inducible cross-resistance to vernamycin B alpha was demonstrated in disk diffusion tests.

Use of an immunoperoxidase method for identification of Bacteroides fragilis

An indirect immunoperoxidase (IP) slide test was evaluated for the laboratory identification of Bacteroides fragilis. Antigen-antibody complexes were detected with goat anti-rabbit immunoglobulin G-peroxidase conjugate with 3-amino-9-ethyl-carbazole as the peroxidase substrate. Ninety-one percent of 44 B. fragilis strains tested were IP positive (3+ to 4+ reactions) with greater than or equal to 1:160 dilutions of rabbit antiserum produced against whole cells of B. fragilis ATCC 23745. The antiserum was species specific. No cross-reactions were observed with 35 Bacteroides strains of other species or with a variety of facultative or aerobic gram-negative bacilli. Four B. fragilis strains were IP negative. One of these (VPI 2393) was the deoxyribonucleic acid (DNA) homology group II reference strain. The other three were clinical isolates. IP-negative and representative IP-positive strains were tested for DNA homology with the type strains for DNA homology groups I and II (VPI 2553 and VPI 2393). Two of the three clinical isolates were classified as DNA homology group II, and the remaining strain was classified as a group I. Capsular material known to be unique to B. fragilis was common to both DNA homology groups as indicated by reactions with purified anticapsular antiserum. The IP technique provides a suitable alternative to fluorescent microscopy for the rapid immunological identification of B. fragilis.