Hepatocellular iron accumulation and increased cell proliferation in polychlorinated biphenyl-exposed Sprague-Dawley rats and the development of hepatocarcinogenesis

Polychlorinated biphenyls (PCBs) are liver-tumor promoters in rodents, but the underlying mechanisms have not been fully elucidated. Tissue sections from the PCB bioassay reported by Mayes et al. 1998, Toxicol Sci., 41-66, were evaluated by histopathological techniques that included immunohistochemistry. In females, and to a much lesser extent in males, iron accumulation in hepatocytes was found at the 26th-week sacrifice, which was pronounced in the mid- and high-dose Aroclor-1254 and -1260 groups. At 52 weeks, large accumulations of iron were also present in Kupffer cells of females, and dose-related increases in proliferating cell nuclear antigen (PCNA) hepatocyte labeling indices were found in both males and females. These changes preceded the formation of liver tumors, which were not generally found until 78 weeks. Glutathione S-transferase placental (GSTP) positive foci were present at 52 weeks in high-dose Aroclor-1254 and -1260 female groups, and small foci were found in some Aroclor 1254-exposed female rats at 26 weeks, along with centrilobular hepatocytes expressing GSTP. The results of this study suggest that PCB-induced iron accumulation in hepatocytes is an early event that may be related to tumor formation, especially in female rats. In both males and females, increases in cell proliferation at 52 weeks were statistically significantly correlated with tumor incidences at termination among the various PCB dosage groups. Consequently, iron accumulations producing oxidative damage, and enhanced cell proliferation resulting in tumor promotion may be components in the mode of action for PCB-induced hepatocarcinogenesis in rodents.

Ion-beam-sputtering/mixing deposition of calcium phosphate coatings. I. Effects of ion-mixing beams

Ion-beam-sputtering/mixing deposition was used to produce thin calcium phosphate coatings on titanium substrate from the hydroxyapatite target. The mixing beam could be either Ar(+) or N(+) ions. It was found that as-deposited coatings were amorphous. No distinct peak of the hydroxyl group was observed in FTIR spectra of the coatings, but new spectral peaks, brought about during the deposition process, were present for CO(3)(2-). Scanning electron microscopy revealed that the deposited coatings had a uniform and dense structure. The calcium-to-phosphorous ratio of these coatings varied between 2.0 and 3.0. Compared with the calcium phosphate coatings produced by Ar(+) beam-mixing deposition, the calcium phosphate coatings produced by N(+) beam-mixing deposition exhibited a higher dissolution rate in the physiologic saline solution and showed a lower proliferation rate of osteoblast cells.

Epithelial membrane protein 2, a 4-transmembrane protein that suppresses B-cell lymphoma tumorigenicity

A murine homologue of the epithelial membrane protein 2 (EMP2) gene was identified in a search for genes associated with B-cell lymphoma tumorigenicity by using suppression subtractive hybridization. Expression of EMP2 messenger RNA in primary mouse tissues was limited to certain epithelial cell types and the peritoneal lymphoid compartment. EMP2 was expressed in the poorly tumorigenic DAC B-lymphoma cell line but was significantly down-regulated in a subline selected for in vivo tumor formation in Balb/c mice. Recombinant restoration of EMP2 expression in the subline suppressed its tumorigenicity, suggesting that loss of EMP2 was a causal factor in the malignant phenotype. Recombinant overexpression of EMP2 was studied in B lymphoma and NIH3T3 cells. EMP2 in both cell types induced cell death on serum deprivation. EMP2-induced cell death correlated with the expression level of EMP2 protein and was prevented by caspase inhibitors Z-VAD and Z-DEVD. These findings for the first time describe an apoptotic effect of a GAS3 family gene in lymphocytes. They also suggest that EMP2 may influence B-lymphoma tumorigenicity through a functional tumor suppressor phenotype. (Blood. 2001;97:3890-3895)

Functionally graded calcium phosphate coatings produced by ion beam sputtering/mixing deposition

Ar+ ion beam sputtering/mixing deposition was used to produce thin calcium phosphate coatings on titanium substrate from hydroxyl-poly-calcium sodium phosphate (HPPA) and HPPA + Ti targets. Three types of coatings (one type of monolayer coating and two types of functionally graded coating) were manufactured. It was found that as-sputtered coatings were amorphous. No distinct hydroxyl band was observed in the FTIR spectra, but new absorption bands were determined for CO3(2-), which resulted during the deposition process. Compositional gradients from the surface to the interior (i.e. adjacent to the substrate) were achieved for the functionally graded coatings. Post-deposition heat treatment indicated that the bonding strength between the coating and the substrate was improved by the use of functionally graded structures.

A focal embolic model of cerebral ischemia in rats: introduction and evaluation

Cerebral thromboembolism is the most common type of acute stroke in the clinical setting. In the present study, we have described a focal embolic model of cerebral ischemia in rat. Cerebral ischemic injury in two different sizes was induced by injection of two different volumes of pre-formed clots into the middle cerebral artery (MCA). Neurological deficits were assessed at 1 and 24 h, respectively, after the MCA embolization. The brain infarction was evaluated with 2,3,5-triphenyltetrazolium chloride (TTC) staining at 72 h following embolic stroke. The incidence of gross hemorrhage was also identified on the TTC-stained brain sections. This study consisted of two groups. In the first group 10 microl of pre-formed clot was injected into MCA (n=10), and in the second group 5 microl of clot was injected (n=10). Embolizing a pre-formed clot resulted in an infarction in the territory irrigated by the MCA. Embolization with the different volume of clots resulted in different sizes of brain infarction, 32.1+/-2.9% (mean+/-S.E.) in the 10-microl group versus 23+/-4.5% (mean+/-S.E.) in the 5-microl group (P<0.05). The infarction size as well as neurological deficits correlated well with the volume of the clot injected. These results thus show that with the procedure described here a reliable and reproducible ischemic injury is produced in the brain. The model is relevant to thromboembolic ischemia in patients, and may offer a useful tool to investigate mechanisms underlying ischemic brain injury. It may also be used to test thrombolytic agents in ischemic brain injury.

Comparative studies on the concentration of rare earth elements and heavy metals in the atmospheric particulate matter in Beijing, China, and in Delft, The Netherlands

Atmospheric particulate matter (APM) was collected at three sampling sites in Beijing, China, from February to June 1998. The concentrations of rare earth elements (REE) and cobalt (Co), zinc (Zn), copper (Cu), cadmium (Cd) and lead (Pb) in the APM were determined by inductively coupled plasma mass spectrometry (ICP-MS). The results obtained in Beijing, China, were compared to that obtained in Delft, the Netherlands, in 1997. The influence of coal combustion was considered. The results demonstrated that the content of APM, the concentrations of REE and Co, Zn, Cd, Pb in the APM in Beijing, China, were higher than that in Delft, the Netherlands. From the ratios of La to Ce, and La to Sm, which may be used as tracers for the origin of the REE, it is concluded that the origins of REE in China differ from those in the Netherlands.

Recursive solution for beam dynamics of periodic focusing channels

We present recursive analysis for beam dynamics of periodic focusing channels based on the Fourier coefficients of the focusing function. Formulas for orbit stability and the envelope function are derived. The results should be useful for numerical calculation and for developing analytical understanding of channels employing extended focusing elements. Applications to muon ionization cooling channels are discussed.

Patency of cerebral microvessels after focal embolic stroke in the rat

In patients with thrombotic stroke, the occluded artery often reopens over time. This results through a natural dissolution of the occluding material, and fragments of the material may move downstream to obstruct distal arteries. The current study was undertaken to investigate the patency of brain microvessels at varying time intervals after injection of a preformed clot into the right internal carotid artery of rats. Cerebral microvessels in brain sections were visualized using immunohistochemistry for fibronectin (detecting existing microvessels) and Evans blue (visualizing perfused microvessels). The percentage of patent microvessels was calculated as the number of Evans blue-positive microvessels divided by the number of fibronectin-positive microvessels. In normal control animals, results showed that 98% +/- 3% (mean +/- SD) of microvessels in the cortex and 94% +/- 14% in the striatum were patent. In the ischemic animals, immediately after clot injection, microvessels in the cortex and striatum were occluded, mainly in the territory irrigated by the middle cerebral artery. One hour after clot injection, microvessels had reopened in most of the cortex but remained occluded in some portions of the striatum, possibly as a result of downstream movement of fragments formed from the original clot. By 3 hours after clot injection, microvessels in the cortex were patent in all animals, whereas in the striatum microvessels were patent in 50% of the animals. In the other 50%, small striatal perfusion deficits persisted. At 24 hours after clot injection, microvessels were patent in both the cortex and striatum of all animals except one. These findings suggest that intracerebral clots dissolve spontaneously in a relatively short period of time, but that fragments formed from the clot may obstruct more distal blood vessels. It is likely that clot fragments lodge in arteries with lower blood flow and poor collateral perfusion, where they continue to cause ischemia for a longer duration. These results may in part explain the resistance of the striatum to neuroprotective strategies used for the treatment of focal cerebral ischemia.

Molecular dynamics simulations of the gramicidin A-dimyristoylphosphatidylcholine system with an ion in the channel pore region

To investigate the process of ion permeation in an ion channel systematically, we performed molecular dynamics (MD) simulations on a gramicidin A (GA)-phospholipid model system with an ion in the channel pore region. Each of the three types of ions (Ca2+, Na+ Cl-) was placed at five different positions along the channel axis by replacing a water molecule. MD simulations were performed on each system at constant pressure and constant temperature. The MD trajectories showed that the Ca2+ and Na+ ions could stably fluctuate in the pore region, but the Cl- ion was pushed out because of the unfavorable interaction with the channel. This result is consistent with experimental data. It was also found that the conformation of the GA channel underwent a significant change due to the presence of the ion, and the two ends of the GA monomer were more flexible than its middle region. In particular, the dramatic change of local pore radius near the ion indicated this kind of deformation. The strong interaction between the ion and carbonyl oxygen atoms of GA was the major contributor to this change. Furthermore, it was found that the ethanolamine group of the GA molecule was the most flexible group in the GA channel and often observed to block the entrance of GA. These results imply that the deformation of channel structure plays a very important factor in ion permeation, and the ethanolamine group may play a key role in regulating ion entry into the pore. In conclusion, our results indicate that the ion has a dominant influence on the structure of the GA channel and that the flexibility of the ion channel is a crucial factor in the ion permeation process.

Child rotavirus infection in association with acute gastroenteritis in two Chinese sentinel hospitals

Rotavirus gastroenteritis is an important pediatric disease in China. In a survey of rotavirus infection at two sentinel hospitals in China (Beijing Friendship Hospital and Changchun Children's Hospital), 296 cases were detected. A total of 283 (95.6%) cases of rotavirus infection occurred in children under 5 years of age. Serotype G1 (62%) was most prevalent followed by G2 (28.5%), G3 (5%) and G4 (2%). Mixed infections (n = 8, 3%) were rate, and 16 isolates (5.5%) remained non-typeable. A consistent epidemic occurred during the winter. Rotavirus was responsible for about 61.8% of diarrhea-related hospitalizations in children under 5 years of age, with a mean hospital stay of 5.6 days (1.0-21 days). The estimated rate of rotavirus-attributed hospitalizations was 16/1000 children under 5 years of age per year. Rotavirus-related death is rare in Changchun and Beijing. The present findings suggest that a rotavirus vaccine for the prevention of severe disease and a reduction of treatment costs would be of significant benefit to China.

Dose-dependent neuroprotection with tiagabine in a focal cerebral ischemia model in rat

Enhancement of the inhibitory activity of GABA may protect ischemic neurons. We evaluated the neuroprotective effect of tiagabine, a novel GABA agonist, in reversible focal cerebral ischemia rats subjected to 2h middle cerebral artery (MCA) occlusion. Tiagabine was given at 10, 20 and 40 mg/kg, i.p., 2 h after the onset of reperfusion. We found that post-ischemia treatment with tiagabine improved neurobehavioral outcome and reduced brain infarction volume in a dose-dependent manner. The data suggest that post-ischemic administration of tiagabine is neuroprotective in the focal cerebral ischemia model.

Overexpression of murine fizzy-related (fzr) increases natural killer cell-mediated cell death and suppresses tumor growth

Fizzy-related (fzr) is a recently identified 7WD domain family member implicated in cell cycle regulation of Drosophila and yeast. In this study, the murine homologue of fzr was isolated by suppression subtractive hybridization as a gene with decreased expression during malignant progression of a murine B-lymphoma cell line. Retroviral overexpression of fzr in B-lymphoma cells reduced tumor formation. Those tumors that did arise had diminished or extinguished retroviral Fzr. Surprisingly, fzr overexpression dramatically increased B-lymphoma cell susceptibility to natural killer cell (NK) cytotoxicity, a host-resistant mechanism for tumor formation in this model system. These findings implicate fzr as a new category of genes suppressing B-cell tumorigenesis and suggest a novel role for fzr in the target cell interaction with NK cells.

Diethylnitrosamine exposure-responses for DNA ethylation, hepatocellular proliferation, and initiation of carcinogenesis in rat liver display non-linearities and thresholds

In previous exposure-response studies, we have documented non-linearities for some of the early effects in rat liver of diethylnitrosamine (DEN) and a near no-effect levels for initiation of promotable liver neoplasms at the lowest cumulative exposure of 0. 5 mmol/kg body weight; this in spite of formation of DNA adducts and induction of hepatocellular altered foci (HAF). To extend these investigations, in an initiation segment, young male F344 rats were administered four exposures of DEN ranging from a cumulative total of 0.25 mmol, which is half of the previously used low exposure, up to 2 mmol per kg body weight, an effective initiating exposure. These exposures were achieved by once weekly intragastric instillations of one-tenth the total exposures for up to 10 weeks. The initiation segment was followed by a 4 week recovery segment, to allow for remission of acute and subchronic effects of DEN, after which the groups were maintained on 0.06% phenobarbital in the diet for 24 weeks to promote liver tumor development in order to assess initiation. During and after initiation and at the end of recovery, selected groups were studied for several crucial effects involved in hepatocarcinogenicity. The low exposure produced a low-level of DNA ethylation at both 5 and 10 weeks of exposure, measured as O(4)-ethylthymidine, the most persistent promutagenic ethylation product. At the 5 week interval, the adduct values of the higher exposures were less than proportional to the increment of exposure, suggestive of nonlinearity. Assessment of cellular proliferation by staining for proliferating cell nuclear antigen revealed that the lowest exposure did not increase the replicating fraction of hepatocytes during the initiation (10 weeks) or recovery (4 weeks) segments, whereas in the three higher exposure groups, proliferation was increased in relation to dose and time. Preneoplastic HAF expressing glutathione S-transferase-placental-type were present at low multiplicity in control livers and their multiplicity was increased in all exposure groups by the end of exposure, at which time the increase in the high exposure group was disproportionately greater than the increment of exposure. After phenobarbital administration in the promotion segment, all exposure groups exhibited further HAF increases at 39 weeks. At the end of the promotion segment, no hepatocellular neoplasm was found in 80 controls or in 40 rats in the low exposure group. In the mid-low exposure group, which was the previously studied low exposure, only one adenoma was found, yielding a 3% incidence, while in the two higher exposure groups, 32 and 80% of rats exhibited liver neoplasms, which were increased disproportionately greater than the increments of exposure. Thus, the findings document non-linearities of early DEN effects and at the lowest cumulative dose, a no-effect level (NEL) or threshold for initiation of promotable liver neoplasms. These findings provide a conceptual basis for understanding why low-level exposures to DNA-reactive carcinogens may convey no cancer risk.

Essential amino acids affect interstitial dopamine metabolites in the anterior piriform cortex of rats

The anterior piriform cortex (APC) is essential for the anorectic reactions to an amino acid-imbalanced diet, and it also responds to repletion of the limiting amino acid. In the present study, we examine the dynamic changes of the interstitial dopamine metabolites in the APC following feeding of either an amino acid-corrected or -imbalanced diet. Microdialysates, collected from the APC, were analyzed using HPLC with electrochemical detection. The concentrations were 19.7 +/- 4.8 microg/L for 3, 4-dyhydroxyphenylacetic acid and 25.1 +/- 4.4 microg/L for homovanillic acid, respectively, in the baseline dialysates. After diet treatments, no significant changes occurred in 3, 4-dyhydroxyphenylacetic acid in the corrected (n = 7) or imbalanced (n = 9) groups vs. the basal group (n = 7). However, after feeding the threonine-corrected diet, the concentration of homovanillic acid was significantly less (P < 0.01) than after the basal and imbalanced diets. The homovanillic acid level in the corrected group was already significantly lower than in the basal group by 20 min (P < 0.05), and reached its lowest level at 70 min (P < 0.05). The concentrations of homovanillic acid in the corrected group remained at this low level until the end of the experiment. The present results introduce the idea that the dopaminergic system is involved in the feeding responses to essential amino acid repletion.

Constructing the suitable initial configuration of the membrane-protein system in molecular dynamics simulations

A method for constructing the suitable initial configuration of the membrane-protein system for molecular dynamics (MD) simulations is presented. This method could provide some hydrated initial configurations and help us to determine the best surface area of the system by contracting the surface area and comparing the optimized lowest energy of the system by energy minimization. The gramicidin A (GA) channel in;the fully hydrated dimyristoylphosphatidylcholine (DMPC) bilayer was used as our model. Three configurations with different surface areas were selected and applied for one 400 ps and two 300 ps MD simulations at constant pressure and temperature. All simulations were fairly stable without any constraints. Through analysis of the MD trajectories we found that the system with the best surface area was more stable than the other two systems, whose sizes were changed in the simulations. Further analysis of the bilayer normal length and the order parameters of the lipid alkyl tails indicates that the system with the best surface area shows some characteristics of the L(alpha) phase, while both the smaller and the larger size systems have distinct deviations from the L(alpha) phase that we expect. This illustrates that the correct surface area and the suitable initial configuration have an important influence on the phase of the membrane in the MD simulation. In addition, by comparing the root mean square differences of GA relative to the initial structure and interaction energy between different components of the system for all three systems, we find that the state of the DMPC bilayer has exerted a significant influence on the structure of GA. All these results demonstrate the validity of our method for constructing the initial configuration of the membrane-protein system for MD simulations.

Morphological changes of spermatozoa in proximal vas deferens after vasectomy

AIM

To investigate the morphological changes of spermatozoa in the proximal vas deferens after vasectomy.

METHODS

Proximal vas deferens fluids were collected from 79 fertile men (group A) and 64 vasectomized men (group B) during the operations of vasectomy or vasovasostomy. Sperm morphology in the proximal vas deferens was analyzed after staining with the modified Papanicolaou method.

RESULTS

The percentage of spermatozoa with a normal oval head from group B (50. 7% +/- 21.7%) was significantly lower than that of group A (75.2% +/- 11.1%). The data in group A was similar to those of normal semen and therefore represents the physiological condition of the proximal vas deferens sperm of fertile men. There were no significant differences in the percentages of normal oval heads in group B with the time since vasectomy.

CONCLUSION

After vasectomy, the spermatozoa in the proximal vas deferens and epididymis were continuously degenerating and being replenished by spermatozoa coming from testis. The obvious morphological degeneration occurred in the sperm tail and spermatozoa with a small oval head and amorphous heads were increased.

The role of humic substances in drinking water in Kashin-Beck disease in China

We conducted in vitro and in vivo assays in a selenium-deficient system to determine if organic matter (mainly fulvic acid; FA) is involved in a free radical mechanism of action for Kashin-Beck disease. Cartilage cell culture experiments indicated that the oxy or hydroxy functional groups in FA may interfere with the cell membrane and result in enhancement of lipid peroxidation. Experiments with rats demonstrated that toxicity from FA was reduced when the hydroxy group was blocked. Induction of lipid peroxidation by FA in liver and blood of rats was similar to that exhibited by acetyl phenyl hydrazine. FA accumulated in bone and cartilage, where selenium rarely concentrates. In addition, selenium supplementation in rats' drinking water inhibited the generation of oxy-free radicals in bone. We hypothesized that FA in drinking water is an etiological factor of Kashin-Beck disease and that the mechanism of action involves the oxy and hydroxy groups in FA for the generation of free radicals. Selenium was confirmed to be a preventive factor for Kashin-Beck disease.

Determination of the thermogenesis curves and studies of the thermodynamics and thermokinetics of seed germination

The thermogenesis curves of the germination of different rice and tree seeds were determined and studied by using a newly constructed microcalorimeter. The thermogenesis curves of the germination of the seeds demonstrate the existence of physiological triphasic patterns, which include imbibition, activation and growth stages in the germination process. The thermodynamics and thermokinetics of the main growth phase of the growth stage in the germination process have been studied. The growth heat effect (deltaH), the growth rate constant (k), the growth inhibitory factor (s) and deceleration rate constant (beta) have been determined and calculated, In addition, the experimental thermokinetic equations of the growth stage in the seed germination process have been established.

Inhibition of norepinephrine release in the rat ventromedial hypothalamic nucleus in essential amino acid deficiency

Effects of dietary amino acid deficiency on interstitial levels of norepinephrine (NE) were assessed in the ventromedial hypothalamic nucleus (VMH). Microdialysates, collected from the VMH, were analyzed using high pressure liquid chromatography with electrochemical detection (HPLC-EC). Ingestion of an amino acid imbalanced diet, which causes a rapid deficiency of the limiting amino acid, induced a significant decrease in the NE concentration from the VMH. The changes in the NE concentration appeared 60 min after diet ingestion and the lowest NE level was observed at 180 min. The present results suggest that ingestion of an amino acid imbalanced diet inhibits NE release in the VMH and support the hypothesis that the VMH plays a role in the integration of signals for the feeding responses to changes in essential amino acid availability.

Nonlinearities in 2-acetylaminofluorene exposure responses for genotoxic and epigenetic effects leading to initiation of carcinogenesis in rat liver

The dose responses for several effects of low-level limited exposures to 2-acetylaminofluorene (AAF) in the livers of male Fischer 344 rats were measured and a subsequent phenobarbital tumor promotion regimen was used to manifest initiation of carcinogenesis. Three doses over a 10-fold range yielding cumulative total exposures of 0.126, 0.42, and 1.26 mmol AAF/kg body weight were achieved by daily intragastric instillation for up to 12 weeks with interim terminations. This was followed by 24 weeks administration of 500 ppm phenobarbital (PB) in the diet to promote liver tumor development. At 12 weeks at the end of AAF administration, all exposures produced adducts in liver DNA, measured by 32P postlabeling, and the level of adducts increased with exposure, except that the high exposure did not produce a dose proportional increase. Measurement of arylsulfotransferase activity, a key enzyme in the metabolic activation of AAF, revealed that in livers from the high exposure animals, the enzyme was inhibited. To assess for toxicity, the centrilobular zone of glutamine synthetase-positive hepatocytes was quantified immunohistochemically at 12 weeks. The area of the zone was reduced in the high exposure group and there was a trend to reduction in relationship to exposure. The two lower exposures to AAF produced no increase in cell proliferation, whereas the high exposure resulted in a marked increase, about 8-fold over controls. Initiation was assessed by induction of hepatocellular altered foci (HAF) that expressed the placental form of glutathione S-transferase. AAF induced HAF in the high exposure group, 9-fold at 8 weeks and 170-fold at 12 weeks compared to controls. In rats maintained on PB for 24 weeks after exposure, the multiplicity of HAF increased in controls and comparably in the low and mid exposure groups, but remained at the about the same high level in the high exposure group. The high exposure produced a substantial incidence of benign neoplasms by 12 weeks, and with promotion by 36 weeks, all rats developed hepatocellular neoplasia. In the mid exposure group, only one adenoma occurred at 36 weeks in 17 rats, while in the low exposure group, no liver tumor occurred in 23 rats. Thus, these findings document nonlinearities for some of the effects of AAF, with supralinear effects at the high exposure for cell proliferation and induction of HAF, and a no-observed-effect level for induction of promotable liver neoplasms at the lowest cumulative exposure of 0.126 mmol/kg, in spite of the formation of DNA adducts. We conclude that the effects of this DNA-reactive hepatocarcinogen leading to initiation exhibit nonlinearities and possible thresholds.

CD1 presents antigens from a gram-negative bacterium, Haemophilus influenzae type B

Human CD1 is a family of nonpolymorphic major histocompatibility complex class I-like molecules capable of presenting mycobacterial lipids, including lipoarabinomannan (LAM), to double-negative (DN; CD4(-) CD8(-)) as well as CD8(+) T cells. Structural similarities between LAM and the capsular polysaccharides of gram-negative bacteria led us to consider the latter as candidate CD1 ligands. We derived two CD1-restricted DN T-cell populations which proliferated to Haemophilus influenzae type b (Hib) antigen. One T-cell population also proliferated to proteinase K-treated Hib antigen, suggesting that it recognized a nonpeptide. Our work thus expands the universe of T cell antigens to include nonpeptides distinct from mycobacterial lipids and suggests a potential role for CD1-restricted T cells in immunity to Hib.

A surgical approach to extensive tumors in the pterygopalatine fossa extending into the maxillary sinus

PURPOSE

This article describes a surgical approach to extensive tumors in the pterygopalatine fossa extending into the maxillary sinus.

TECHNIQUE

The Barbosa approach was modified by adding a lateral incision in the mandibular gingivobuccal fold from the canine tooth to the retromolar area.

RESULTS

This technique allowed a large, inferiorly based flap to be raised, which includes the parotid gland. The masseter and temporalis muscles was divided horizontally, and the ascending ramus of the mandible was osteotomized between the mandibular angle and the sigmoid notch and reflected to expose the tumor in the pterygopalatine fossa and maxillary sinus.

CONCLUSION

This technique is especially useful to tumors in the pterygopalatine fossa extending into the maxillary sinus.

Investigating the dielectric effects of channel pore water on the electrostatic barriers of the permeation ion by the finite difference Poisson-Boltzmann method

In this paper, the finite difference Poisson-Boltzmann (FDPB) method with four dielectric constants is developed to study the effect of dielectric saturation on the electrostatic barriers of the permeation ion. In this method, the inner shape of the channel pore is explicitly represented, and the fact that the dielectric constant inside the channel pore is different from that of bulk water is taken into account. A model channel system which is a righthanded twist bundle with four alpha-helical segments is provided for this study. From the FDPB calculations, it is found that the difference of the ionic electrostatic solvation energy for wider domains depends strongly on the pore radius in the vicinity of the ion when the pore dielectric constant is changed from 78 to 5. However, the electrostatic solvation energy of the permeation ion can not be significantly affected by the dielectric constant in regions with small pore radii. Our results indicate that the local electrostatic interactions inside the ion channel are of major importance for ion electrostatic solvation energies, and the effect of dielectric saturation on the electrostatic barriers is coupled to the interior channel dimensions.

Performance evaluation of filtered backprojection reconstruction and iterative reconstruction methods for PET images

The filtered backprojection (FBP) algorithm and statistical model based iterative algorithms such as the maximum likelihood (ML) reconstruction or the maximum a posteriori (MAP) reconstruction are the two major classes of tomographic reconstruction methods. The FBP method is widely used in clinical setting while iterative methods have attracted research interests in the past decade. In this paper we studied the performance of the FBP, the ML and the MAP methods using simulated projection data. The experiment showed that the MAP algorithm generated superior image quality in terms of the bias, the variance, and the average mean squared error (MSE) measures.

Enhancement of experimental colon cancer by genistein

Several phytochemicals and micronutrients that are present in fruits and vegetables are known to exert cancer chemopreventive effects in several organs, including the colon. Among them, the soybean isoflavonoid genistein received much attention due to its potential anticarcinogenic, antiproliferative effects and its potential role in several signal transduction pathways. The present study was designed to investigate the effect of genistein on azoxymethane (AOM)-induced colon carcinogenesis and to study its modulatory role on the levels of activity of 8-isoprostane, cyclooxygenase (COX), and 15-hydroxyprostaglandin F2alpha dehydrogenase (15-PGDH) in the colonic mucosa and colon tumors of male F344 rats. At 5 weeks of age, groups of male F344 rats were fed control (AIN-76A) diet or a diet containing 250 ppm genistein. Beginning 2 weeks later, all animals except those in the vehicle-treated groups were given weekly s.c. injections of AOM (15 mg/kg body weight) for 2 successive weeks. All rats were continued on their respective dietary regimen for 52 weeks after AOM treatment and were then sacrificed. Colon tumors were evaluated histopathologically. Colonic mucosae and tumors were analyzed for COX, 15-PGDH, and 8-isoprostane levels. Administration of genistein significantly increased noninvasive and total adenocarcinoma multiplicity (P < 0.01) in the colon, compared to the control diet, but it had no effect on the colon adenocarcinoma incidence nor on the multiplicity of invasive adenocarcinoma (P > 0.05). Also, genistein significantly inhibited the 15-PGDH activity (>35%) and levels of 8-iosoprostane (50%) in colonic mucosa and in tumors. In contrast, genistein had no significant effect on the COX synthetic activity, as measured by the rate of formation of prostaglandins and thromboxane B2 from [14C]arachidonic acid. The results of this investigation emphasize that the biological effects of genistein may be organ specific, inhibiting cancer development in some sites yet showing no effect or an enhancing effect on the tumorigenesis at other sites, such as the colon. The inhibition of 8-isoprostane levels by genistein indicates its possible antioxidant potential, which is independent of the observed colon tumor enhancement, yet this agent may also possess several biological effects that overshadow its antioxidant potential. The exact mechanism(s) of colon tumor enhancement by genistein remain to be elucidated; it is likely that its colon tumor-enhancing effects may, at least in part, be related to inhibition of prostaglandin catabolic enzyme activities.

Assessment of chronic toxicity and carcinogenicity in rats of Wingstay 100, a rubber antioxidant/antiozonant

The chronic toxicity and carcinogenicity of Wingstay 100 (W 100), a rubber antioxidant/antiozonant, were studied in Fischer 344 (F 344) rats in two chronic studies. Earlier genetic studies indicated that the product had weak activity in a bacterial mutation assay, but lacked activity in chromosomal aberration assays. In an one year study, both genders of F 344 rats were exposed to 53, 310 or 1900 ppm in NIH-07 diet for 52 weeks, and sacrifices were made at 38, 52 and 64 weeks. No test substance related deaths occurred, although the high dose of 1900 ppm caused a decrease in body weight gain and food consumption in both genders. Red blood cell mean corpuscular volume was significantly increased at 38 weeks, accompanied by a significant decrease in mean corpuscular hemoglobin concentration. At 52 weeks, the red blood cell count and hemoglobin values were also significantly decreased in high dose animals of both genders. Total bilirubin and cholesterol were increased in high dose animals of 38 and 52-week sacrifices. During the 3 month recovery, hematology parameters, bilirubin and cholesterol returned to control values. Total protein was reduced in high dose animals of both genders, throughout the entire exposure and recovery periods. W 100 also produced increases in relative liver, spleen, heart and kidney weights in high dose animals. Both genders of all W 100 groups exhibited significant increases in urothelial cell proliferation (measured by PCNA) and adaptive hyperplasia. No regenerative hyperplasia, preneoplasia, or neoplasia were present. There was microscopic evidence of extramedullary erythropoiesis in the spleen and liver of high dose animals in both genders, otherwise no other pertinent microscopic finding was evident. In parallel, an accelerated bioassay (ABA) was conducted, which is a mechanistic initiation/promotion carcinogenicity study designed to assess tumor induction and promotion potential of a test substance in major organs of carcinogenesis. The present study was conducted in male F 344 rats for 38 weeks. The target sites chosen for the ABA were liver and urinary bladder and the dose for W 100 was 1900 ppm previously established to be a toxic dose. The liver tumor initiator was diethylnitrosamine (DEN), and the urinary bladder initiator was N-butyl N-(4-hydroxybutyl) nitrosamine (BBN). The initiators were administered during the first 14 weeks followed by the promoters. The promoters, phenobarbital (PB) for the liver and nitrilotriacetate (NTA) for the urinary bladder, were administered during the last 24 weeks of the study after the test substance. The study had 11 test groups including a negative control. The critical comparisons for initiating activity were conducted between groups 3 (PB) and 6 (W 100 + PB) for the liver and groups 8 (NTA) and 11 (W 100 + NTA) for the urinary bladder. The critical comparisons for promoting activity were conducted between groups 2 (DEN) and 5 (DEN + W 100) for the liver and groups 7 (BBN) and 10 (BBN + W 100) for the urinary bladder. There were 26 and 38-week sacrifices. In this study, most body weight reductions were due to DEN. At 26 weeks, significant increases in liver weights were present in all PB-exposed groups. Significant increases in renal weights occurred in all NTA, BBN and DEN groups. A similar organ weight pattern was present at 38 weeks. At 26 weeks, there were hepatocellular (33%) and urothelial (67%) tumors present in positive control groups (DEN/DEN + PB/BBN/BBN + NTA). In contrast, in the DEN + W 100 (5) and the BBN + W 100 (10) groups no tumors were present indicating absence of promotion. In addition, no tumors were present in groups 6 (W 100 + PB) or 11 (W 100 + NTA) indicating absence of initiation. At 38 weeks, the incidences of hepatocellular adenomas and carcinomas in positive control group (DEN) was 44%. The incidence of urothelial adenomas and carcinomas was 67% in group 7 (BBN). In contrast, groups 5 (DEN + W 100) or group 10 (BBN + W 100) had

Effects of tea, decaffeinated tea, and caffeine on UVB light-induced complete carcinogenesis in SKH-1 mice: demonstration of caffeine as a biologically important constituent of tea

Oral administration of green or black tea inhibited UVB light-induced complete carcinogenesis in the skin of SKH-1 mice. Green tea was a more effective inhibitor than black tea. Oral administration of decaffeinated green or black tea resulted in substantially less inhibitory activity than did administration of the regular teas, and in one experiment, administration of a high-dose level of the decaffeinated teas enhanced the tumorigenic effect of UVB. Oral administration of caffeine alone had a substantial inhibitory effect on UVB-induced carcinogenesis, and adding caffeine to the decaffeinated teas restored the inhibitory effects of these teas on UVB-induced carcinogenesis. In additional studies, topical application of a green tea polyphenol fraction after each UVB application inhibited UVB-induced tumorigenesis. The results indicate that caffeine contributes in an important way to the inhibitory effects of green and black tea on UVB-induced complete carcinogenesis.

Increase of interleukin-1beta mRNA and protein in the spinal cord following experimental traumatic injury in the rat

Interleukin-1 beta (IL-1beta) is a major mediator of inflammation and a growth promoter for many cell types that could play an important role in the consequences of traumatic spinal cord injury (SCI). In the present study, the expression of IL-1beta and its mRNA was determined in the rat spinal cord following a standardized contusion injury. IL-1beta mRNA, measured with quantitative RT-PCR, was significantly increased in the lesion site by 1 h after SCI (35.2 +/- 5.9 vs. 9.1 +/- 2.1 pg/mg RNA, n = 3, P < 0.05) and remained significantly higher than in the normal spinal cord for at least 72 h post-injury (p.i.). IL-1beta mRNA levels in tissue immediately caudal to the lesion site did not change after the injury. IL-1beta protein levels, measured by an ELISA, were determined at the lesion site and in cerebrospinal fluid (CSF) and serum samples. IL-1beta levels in the CSF and serum were much lower than in the spinal cord. At the lesion site, IL-1beta was increased significantly by 1 h p.i., peaked at 8 h (32.3 +/- 0.1 vs. 7.6 +/- 1.9, ng/g tissue, n = 5, P < 0.05) and remained significantly higher than normal through at least 7 days p.i. These results suggest that the increased IL-1beta mRNA and protein levels are an early and local response at the lesion site that could trigger other, later, responses to traumatic SCI.

Chemoprevention of colon carcinogenesis by dietary perillyl alcohol

Epidemiological studies suggest that consumption of diets containing fruits and vegetables, major sources of phytochemicals and micronutrients, may reduce the risk of developing cancer of the colon. Several phytochemicals and micronutrients present in fruits and vegetables are known to exert cancer-chemopreventive effects in several organs, including the colon. Monoterpenes such as d-limonene and perillyl alcohol derived from orange peels and lavender, respectively, have been shown to possess chemopreventive properties against mammary, liver, and/or lung carcinogenesis. The present study was designed to investigate the efficacy of dietary 40 and 80% maximum tolerated dose (MTD) levels of perillyl alcohol on azoxymethane (AOM)-induced colon carcinogenesis. The effect of this agent on the process of apoptosis in colon tumors was also investigated. Prior to the efficacy study, the MTD of perillyl alcohol was determined in male F344 rats in a 6-week subchronic toxicity study and found to be a 2.5-g/kg diet when added to the AIN-76A diet. At 5 weeks of age, groups of male F344 rats were fed control (AIN-76A) diet or diets containing 1 and 2 g perillyl alcohol/kg diet, representing 40 and 80% MTD levels, respectively. At 7 weeks of age, all animals except those in the vehicle-treated groups were given two weekly s.c. injections of AOM (15 mg/kg body weight/week). All animals were continued on their respective dietary regimen for 52 weeks after AOM treatment and then sacrificed. Colon tumors were evaluated histopathologically using routine procedures. Perillyl alcohol at the 1-g/kg level significantly inhibited the incidence (percentage of animals with tumors) and multiplicity (tumors/ animals) of invasive adenocarcinomas of the colon, whereas perillyl alcohol at 2 g/kg diet inhibited the incidence of total adenocarcinomas of the colon and small intestine as compared to the control diet. Our studies also indicate that the colon tumors of animals fed perillyl alcohol exhibited increased apoptosis as compared to those fed the control diet. These results demonstrate the potential chemopreventive activity of perillyl alcohol against colon carcinogenesis. The chemopreventive activity of perillyl alcohol is mediated through the tumor cell loss by apoptosis.

Exploring the interaction between D-xylose isomerase and D-xylose by free energy calculation

The numerical quadrature thermodynamic integration method is used to investigate enzyme-substrate interaction of D-xylose isomerase. A screening function for the coulombic interaction is introduced into the simulation to correct the effect of finite cut-off radius for the non-bonded interaction. The binding free energy difference for D-xylose with D-xylose isomerase and its N184D mutant has been calculated, and the result 3.9 +/- 1.2 kJ/mol agrees well with experimental data of 4.38 kJ/mol. In addition, the structure and dynamics of enzyme-substrate complex were simulated for mutant and wild-type enzyme, respectively. Analysis of the structures and intramolecular interactions of the complexes were found to be valuable for understanding the reaction mechanism of the enzyme D-xylose isomerase.

Diethylnitrosamine exposure-responses for DNA damage, centrilobular cytotoxicity, cell proliferation and carcinogenesis in rat liver exhibit some non-linearities

The exposure-responses for several effects of limited exposures to diethylnitrosamine (DEN) in the livers of male Fischer 344 rats were measured and phenobarbital promotion was used to enhance expression of initiation of carcinogenesis. Five doses ranging from a cumulative total of 0.5 to 4 mmol DEN per kg body weight were given as weekly i.p. injections for 10 weeks. This was followed by 4 weeks recovery, after which the groups were maintained on either a basal diet or 0.05% phenobarbital (PB) to promote liver tumor development. All doses of DEN produced ethylation in liver DNA, which increased with dose. Indicative of toxicity, the centrilobular zone of glutamine synthetase-positive hepatocytes was reduced in relationship to exposure up to a cumulative exposure of 3 mmol/kg. The two lower exposures to DEN produced no increase in cell proliferation, whereas higher exposures resulted in marked increases, approximately 4-fold between 1.0 and 2.0 mmol/kg cumulative. At the end of the recovery period (14 weeks), hepatocellular altered foci (HAF), which expressed the placental form of glutathione S-transferase, were induced by all exposures, with an increase of approximately 4-fold between the exposures of 1.0 and 2.0 mmol/kg being the greatest. In rats maintained on basal diet or PB for 24 weeks after exposure, HAF increased further and with exposures of 2.0 mmol/kg and above, all rats developed hepatocellular carcinomas. With 1.0 mmol/kg, no liver tumor occurred in 12 rats without promotion, whereas in those given PB, two adenomas and two carcinomas were present in 12 rats. At the lowest exposure of 0.5 mmol/ kg, no tumor occurred in rats on basal diet, although HAF increased approximately 7-fold. With PB promotion, only one adenoma developed in 12 rats and HAF increased another 2-fold. Thus, the findings document non-linearity for some of the effects of DEN and a near no-effect level for initiation of promotable liver neoplasms at the lowest exposure in spite of a substantial induction of HAF.

Production of tumor necrosis factor in spinal cord following traumatic injury in rats

Production of tumor necrosis factor (TNF) in the spinal cord following traumatic injury has been studied. In these experiments, the level of TNF was examined in the homogenate of the spinal cord, cerebrospinal fluid (CSF) and serum (n = 56). TNF could be detected in the injured spinal cord but not in the normal spinal cord. The TNF level increased in the spinal cord after the injury. At the lesion site, a maximal TNF concentration was observed 1 h after the injury, and the TNF concentration remained at this level until 8 h after the injury. Thereafter, it decreased gradually. However, TNF still could be detected 72 h after the injury. No TNF could be detected in the CSF and serum, collected from rats both with and without spinal cord injury (SCI). This study thus suggests that TNF is produced locally in the spinal cord following traumatic injury, and this TNF production is caused by the injury. The present results also demonstrate that TNF production is an acute and rapid reaction in the spinal cord following traumatic injury.

[Effect of qigong on heart-qi deficiency and blood stasis type of hypertension and its mechanism]

Comparative study was performed on the Heart-Qi Deficiency and Blood Stasis type (HQDBS) of hypertensive patients treated with Qigong. The results showed that the clinical symptoms alleviated, cardiac morphology and function, hemorheology and erythrocyte deformity were improved. After one year of practicing Qigong, plasma histofibrinogen activation inhibitor (PAI) and VIII factor related antigen (VIII R: Ag) levels decreased, while plasma tissue fibrinolytic activator (t-PA) and anti-thrombogen III (AT-III) levels increased. Capillary blood velocity of nailfold microcirculation raised from 0.2940 +/- 0.0206 mm/s to 0.3045 +/- 0.0236 mm/s, the diameter and length of afferent limb tended to increase. The above data indicated that Qigong could benefit HQDBS. This might be the mechanism by which HQDBS type of hypertension was treated.

A study of the mechanism of butachlor-associated gastric neoplasms in Sprague-Dawley rats

Long term administration of butachlor to Sprague-Dawley rats in a previous bioassay, resulted in the induction of gastric neoplasms which occurred only in the highest dose group (3000 ppm in the diet), primarily in females and specifically in the fundic region. The tumors were a composite of highly undifferentiated enterochromaffin-like (ECL) cells and mucus producing cells with morphologic characteristics unlike those previously described in the rat stomach. Mucosal atrophy of marked intensity was a consistent feature of the gastric mucosa in animals from the highest dose group. An additional long term study was conducted in female Sprague-Dawley rats at dietary levels of 0, 100, 1000 and 3000 ppm to explore the mechanism(s) involved in the formation of these neoplasms. Cell proliferation was evaluated in both fundic and pyloric regions of the stomachs of rats at multiple time periods from 14 days to 26 months. Mucosal thickness was determined in the fundic region at the same time intervals as were used for cell proliferation studies. Gastric pH and gastric acid production were measured after approximately 21 months of exposure. Serum gastrin levels were analyzed at 14, 60, and 120 days and at 6, 18 and 20 months. Cholecystokinin (CCK)/gastrin receptor binding studies were conducted on samples of four tumors and pooled fundic mucosa from five animals in the control group. Cell proliferation was increased in both the neck and base regions of the fundic mucosa at nearly all time points measured from 14 days to 26 months. The magnitude of the changes in the base region were substantially greater than those in the neck region. Fundic mucosal thickness was decreased beginning at the 30-day time point and continued at all intervals, being less than one half that of controls at 20 and 26 months. Gastric pH in rats from the highest dose was elevated to nearly twice control levels at 21 months. Gastric acid secretion was dramatically decreased in animals from the 3000 ppm group and was moderately decreased in the 1000 ppm group at 21 months. Hypergastrinemia was observed at the 3000 ppm level only, beginning at 120 days with progression to extremely high levels by 18 months. CCK/gastrin receptor binding was demonstrated in all tumors studied, at levels comparable to or higher than that of the pooled control sample. All changes involved only the fundic region, the site of tumor formation. Tumors occurred only in animals from the 3000 ppm level, the only level at which hypergastrinemia occurred.(ABSTRACT TRUNCATED AT 400 WORDS)

Analysis of spermatozoa from the proximal vas deferens of vasectomized men

This study assessed the condition of spermatozoa from the proximal vas deferens of men after vasectomy. The fluids of both proximal vas deferens were collected from 67 vasectomized men by cannulating the vas deferens at the time of vasectomy reversal. Selected sperm parameters were analysed after incubation of the spermatozoa for 30 min at 37 degrees C. Sperm concentration in the proximal vas from vasectomized men (16,312 +/- 21,496 million per ml, geometric mean: 7948 +/- 398 million per ml) was significantly higher than that of fertile men and was maintained at a constant level independent of the duration of vas obstruction. The means of sperm motility (36.2 +/- 26.2%), spermatozoa with normal morphology (50.7 +/- 21.7%), sperm viability (53.0 +/- 25.3%) and hypo-osmotic swelling test (HOS-test, 53.9 +/- 21.7%) were statistically lower than the respective values for normal fertile men. There was no significant correlation between the duration of vas obstruction and the above semen parameters. In 46.4% of vas fluids all spermatozoa were immotile and this condition was more common after 3 years of vasectomy. Immotile spermatozoa in the proximal vas fluids at the time of vasectomy reversal may be an important factor for predicting semen quality and fertilizing ability after vasovasostomy. There were no significant differences in the results of sperm-cervical mucus penetration test (CMPT) between spermatozoa from vasectomized and fertile men. Antisperm antibodies on the surface of spermatozoa from the vas of vasectomized men were determined by the immunobead test (IBT; 78.6% for IgG, 32.1% for IgA) and sperm cervical mucus contact test (SCMC, 36.4%).(ABSTRACT TRUNCATED AT 250 WORDS)

Paternity identification in twins with different fathers

If a female has sexual intercourse with two males at short intervals within the same ovulatory period, superfecundation may occur. This article reports two cases of paternity identification in twins. The results showed that each twin had come from a different father. Thus, great attention should be paid to such a situation when the twin paternity identification is asked for.

Dose response of promotion by butylated hydroxyanisole in chemically initiated tumours of the rat forestomach

The antioxidant food preservative butylated hydroxyanisole (BHA) was tested in an initiation-promotion protocol in which male F344 rats (6 wk old), 27 per group, were gavaged with a single dose of 200 mg N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)/kg. After 3 wk on control diet, test diets containing 0, 60, 300, 1000, 3000, 6000 or 12,000 ppm BHA were fed until termination of the experiment at approximately 110 wk, at which time most animals had died with stomach tumours. MNNG caused a high incidence of tumours in the glandular stomach and forestomach of all groups. Administration of 12,000 and 6000 ppm BHA, but not 3000 ppm or lower doses, caused statistically significant increases in the time-related incidence of MNNG-induced forestomach tumours as analyzed by life table analysis. BHA had no effect on the incidence of tumours in the glandular stomach or oesophagus. Tumour incidences in other organs were not related to BHA dose. No increase in hyperplasia in the oesophagus was evident in the high-dose BHA-treated animals compared with the MNNG-only group. This study provides corroboration that BHA affects only forestomach tumorigenesis and that the dose for enhancement of tumorigenesis is at least 1500-fold greater than human exposure.

[Combined non-operative intervention for retained bile duct stones]

Basket lithotriptor, piezoelectric shock wave lithotripsy, electrohydraulic shock wave lithotripsy, and endoscopic papillosphincterotomy were used to manage respectively 10, 15, 14, and 15 patients with retained intra and extrahepatic bile duct stones that could not be removed with a Dormia basket. In these four group patients the stones ranged from 5 to 25 mm in diameter. A residual stone was fragmented with a basket lithotriptor if its diameter exceeded that of the T tube tract. Shock-wave was used when mechanical lithotripsy was unsuccessful. Endoscopic papillosphincterotomy was carried out in patients with stenosis of the sphincter, or impacted stone at the Ampulla of Vater. Combined biliary lavage, Dormia basket, and choledochoscopy after lithotripsy accelerated clearance of fragments. In these four groups, stone-free rates and reoperation rates were 90, 46.7, 85.7, and 100 percent and 10, 6.6, 14.3, and 0 percent respectively. There were no serious complications.

[Effect of qigong on plasma coagulation fibrinolysis indices of hypertensive patients with blood stasis]

The levels of plasma tissue-type plasminogen activator (tPA), plasminogen activator inhibitor (PAI), VIII factor related antigen (VIIIR:Ag) and anti-thrombin (AT-III) were determined in 40 hypertensive patients with Blood Stasis. The results indicated that the function of coagulation-fibrinolytic system was disturbed. After one year of practising Qigong, plasma PAI and VIII R:Ag levels were decreased, while plasma tPA and AT-III levels increased. It suggested that Qigong could improve the function of coagulation-fibrinolytic system.

Submicrostructure and typing of female genital condylomata

Thirty biopsies from female genital condylomata were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to study structural characteristics and typing of condylomata. It was found that cytoplasmic clearing was marked in acuminate condylomata, diffuse interstitial and epithelial proliferation in nodular condylomata (flat condylomata), and invagination of the lesions into the interstitial tissue or glandular ducts in endophytic condylomata. In nodular condylomata, SEM also showed some structural features similar to those of intra-epithelial neoplasia. Microridges on the surface of squamous cells had villiform of granular changes. On the surface of a percentage of squamous or columnar cells, there were holes with a diameter of about 3 to 5 microns. A number of giant cells were seen among other cells. The cervical squamatization zone contained groups of special cells covered with dense microvilli. TEM of nodular condylomata revealed some pictures resembling active proliferation of tumor cells, such as enlarged or irregular nuclei (large N/C ratio), evaginated or invaginated nuclear membranes, condensed chromatin attached to the inner part of the nuclear membrane, transparent nucleoplasm, and frequent nucleosomes and karyokinesis. Virus particles with the morphological characteristics of HPV (naked hexagon-like particles with an average diameter of 45-50 nm) were seen in some nuclei with markedly condensed chromatin. It is suggested that HPV-induced genital condylomata, especially nodular one (flat condylomata), entail a potential progression to malignancy.

Can the stability of protein mutants be predicted by free energy calculations?

The use of free energy simulation techniques in the study of protein stability is critically evaluated. Results from two simulations of the thermostability mutation Asn218 to Ser218 in Subtilisin are presented. It is shown that components of the free energy change can be highly sensitive to the computational details of the simulation leading to the conclusion that free energy calculations cannot currently be used to reliably predict protein stability. The different factors that undermine the reliability are discussed.

Analysis of spermatozoa from the proximal vas deferens of fertile men

Fluids from the left and right proximal vas deferens were collected from 105 normal fertile men by cannulating the vas deferens during vasectomy, and sperm parameters analysed. Sperm motility (73.1 +/- 13.3%), normal sperm morphology (75.2 +/- 11.1%), sperm viability (72.7 +/- 18.8%) and the hypo-osmotic swelling test (73.3 +/- 19.2%) were in the normal range, compared with that of ejaculated spermatozoa. However, sperm concentration in the proximal vas deferens (6274.6 +/- 5103.8 x 10(6) ml-1 was higher than that in semen. Sperm concentration in the right vas deferens was significantly higher (P < 0.05) than that in the left and the percentage of spermatozoa showing abnormal cervical mucus penetration was significantly higher (47%) for the left than for the right (18%). There were no anti-sperm antibodies on the surface of spermatozoa from the vas deferens as determined by the sperm cervical mucus contact test and immunobead test. These parameters of spermatozoa from the proximal vas may reflect those of spermatozoa from the human cauda epididymis.

Diethylstilbestrol liver carcinogenicity and modification of DNA in rats

Administration of diethylstilbestrol to female Sprague-Dawley rats at 10 mg/kg body weight daily by gavage for 1 year induced liver adenomas and carcinomas and pituitary adenomas. Using the 32P-postlabeling assay for DNA alterations, at 24 h after administration of a single dose of 100 mg/kg, modified bases were found.

Motor evoked potentials in a static load model of spinal cord injury in the rat

Motor evoked potentials (MEPs) are used to evaluate spinal cord injury. In this study, the effect of different grades of static load spinal cord injury on MEPs was examined. Rats (n = 27) were anesthetized, ventilated, and curarized. MEPs were elicited by the stimulation of the right sensorimotor cortex and recorded with a needle electrode placed in the epidural space on the left side at T10. The spinal cord injury was produced by gently placing a weight (20, 35, or 50 g) on the spinal cord at the level of T3. The compression time was 5 minutes. A group of rats in which laminectomies were performed but in which no weight was put on the spinal cord served as a control group. MEPs were recorded before, during, and after the spinal cord lesion was produced. The MEPs in the 0g group were stable. While the spinal cord was compressed, the MEP positive peak latencies increased and the amplitudes decreased and finally disappeared. MEP latencies and amplitudes correlated well with the weight used for spinal cord compression. During spinal cord compression, MEPs vanished, starting from peaks with a longer latency to peaks with a shorter latency. After decompression, the peaks reappeared in a reverse order. This study shows that MEPs are a good parameter for the functional integrity of spinal cord motor pathways in a static load type of injury model.

Congenital absence of vas deferens treated by artificial spermatocele constructed from the tunica vaginalis; report of six cases

Six patients with congenital absence of the vas deferens were treated by artificial spermatoceles (ASCs) in an attempt to collect sperm for subsequent artificial insemination (AI). The ASC was constructed from a flap of tunica vaginalis from the patient. Sperm were aspirated from the ASC each month; there was wide variation in the concentration of sperm recovered [33.0 +/- 48.2 x 10(6) mL-1 (range 0.1-200)] and motility and normal morphology of the sperm were 19.0 +/- 17.9% and 48.8 +/- 23.4% respectively. Although a total of 14 cycles of AI was performed using the aspirated sperm, pregnancy did not result. Both poor sperm recovery and poor motility contributed to this failure. The condition of the epididymis observed during scrotum examination is reported. It is suggested that in some patients with congenital absence of vas deferens, the paired Wolffian ducts may differ from each other in their development.

Thermodynamic integration calculations of binding free energy difference for Gly-169 mutation in subtilisin BPN'

The binding free energy difference for the Gly-169-->Ala-169 (G169A) mutation in subtilism BPN' complexed with a tripeptide substrate analogue is explored using the thermodynamic integration approach. The structure of the mutant enzyme-substrate complex obtained from free energy simulation is in good agreement with experimental X-ray refinement. The near perfect reversibility is obtained in the present work for ensuring the correctness of the free energy calculations. The results of the binding free energy difference are close to similar experimental data.