Linkage analysis in two large Italian pedigrees affected with nail patella syndrome

Nail patella syndrome (NPS) or osteo-onychodysplasia, is an autosomal dominant disorder characterised by nail dysplasia, absent or hypoplastic patellae, iliac horns and nephropathy. Previous studies have demonstrated linkage of the nail patella locus to the ABO and adenylate kinase loci on human chromosome 9q34. Recently, informative recombination events placed the NPS locus within a 1-2 cM interval within D9S60 and the AK1 gene. We describe here linkage analysis performed in two large Italian pedigrees with 10 and 11 members affected, respectively. A set of highly informative markers have been analysed and the allele segregation in the two families confirmed the linkage to chromosome 9. The presence of three recombination events allows definition of the critical region with a centrometric boundary between markers D9S1881 and D9S1840 and a telomeric boundary between markers D9S315 and D9S290.

No requirement for V(D)J recombination in p53-deficient thymic lymphoma

The p53 tumor suppressor is activated in response to a variety of cellular stress signals, although specific in vivo signals that trigger tumor suppression are unknown. In mouse thymocytes, where p53 inactivation leads to tumorigenesis, several observations suggest that V(D)J recombination of T-cell receptor (TCR) loci could provide a DNA damage signal triggering p53-dependent apoptosis and tumor suppression. Inactivation of p53 would allow V(D)J driven mutation of additional cancer genes, facilitating tumorigenesis. Here, we show that mice with a p53 deficiency in thymocytes and unable to carry out V(D)J recombination are not impaired in the development of thymoma. Recombination-activating gene (RAG) deficiencies were introduced into both p53-/- mice and TgTDeltaN transgenic mice, a strain in which 100% of the mice develop thymoma due to thymocyte-specific inactivation of p53 by a simian virus 40 T-antigen variant. V(D)J recombination was dispensable for tumorigenesis since thymomas developed with or without the RAG-1 or RAG-2 gene, although some delay was observed. When V(D)J recombination was suppressed by expression of rearranged TCR transgenes, 100% of the TgTDeltaN mice developed thymoma, surprisingly with reduced latency. Further introduction of a RAG deficiency into these mice had no impact on the timing or frequency of tumorigenesis. Finally, karyotype and chromosome painting analyses showed no evidence for TCR gene translocations in p53-deficient thymomas, although abundant aneuploidy involving frequent duplication of certain chromosomes was present. Thus, contrary to the current hypothesis, these studies indicate that signals other than V(D)J recombination promote p53 tumor suppression in thymocytes and that the mechanism of tumorigenesis is distinct from TCR translocation oncogene activation.

An essential role of myosin light-chain kinase in the regulation of agonist- and fluid flow-stimulated Ca2+ influx in endothelial cells

Cytosolic Ca2+ ([Ca2+]i) plays an important role in endothelial cell signaling. Although it has been suggested that the influx of Ca2+ can be triggered by depletion of intracellular Ca2+ stores, the mechanism (or mechanisms) underlying this phenomenon needs further elaboration. In the present study, involvement of myosin light-chain kinase (MLCK) in the regulation of Ca2+ signaling was investigated in agonist- and fluid flow-stimulated endothelial cells loaded with Ca2+-sensitive dyes. Bradykinin (BK) and thapsigargin caused an increase in [Ca2+]i followed by a sustained rise due to Ca2+ influx from extracellular space and shifted total myosin light-chain (MLC) from the unphosphorylated to the diphosphorylated form. ML-9 (100 microM), an inhibitor of MLCK, abolished Ca2+ influx and prevented MLC diphosphorylation in BK- and thapsigargin-treated cells, but did not affect Ca2+ mobilization from internal stores. Fluid flow stimulation (shear stress=5 dynes/cm2) increased [Ca2+]i and enhanced MLC phosphorylation. ML-9 also inhibited Ca2+ response and MLC phosphorylation in fluid flow-stimulated cells. The Ca2+ influx in response to BK was linearly correlated with the diphosphorylation of MLC in ML-9 treated cells. Effects of ML-5 and ML-7, analogs of ML-9, to inhibit Ca2+ influx paralleled their potencies to inhibit MLCK activity. These findings demonstrate that MLCK plays an essential role in regulating the plasmalemmal Ca2+ influx in agonist- and fluid flow-stimulated endothelial cells. This study is the first to report the close relationship between Ca2+ influx and MLC diphosphorylation.

Influence of duration of exposure to styrene oxide on sister chromatid exchanges and cell-cycle kinetics in cultured human blood lymphocytes in vitro

Styrene-7,8-oxide, an intermediate of styrene, is a known alkylating mutagen. The present study was carried out to investigate the influence of duration of exposure to styrene-7,8-oxide (styrene oxide) on induction of sister chromatid exchanges (SCEs) and inhibition of cell-cycle kinetics using cultured human blood lymphocytes in vitro. Phytohemagglutinin-stimulated whole-blood lymphocyte cultures obtained from heparinized whole blood from healthy donors were exposed to 100 microM styrene oxide for 22, 36, 48 and 72 h. A reduction of SCEs induction with increase in duration of exposure to styrene oxide was observed, i.e. a clear significant inverse relationship between exposure time and frequencies of SCEs induction due to styrene oxide was obtained. Styrene oxide induces significant elevations in unscheduled DNA synthesis DNA repair as well as S-phase synthesis in human blood lymphocytes in vitro, depending on the duration of exposure. The decrease in the induction of SCEs due to styrene oxide with increasing duration of its exposure may be principally due to an increased DNA repair and partly due to an increasing metabolic transformation to styrene glycol with increasing duration of its exposure as well as to some extent due to cell death at the maximum period of exposure. i.e. 72 h. Although the proliferations of lymphocytes exposed to 100 microM styrene oxide were significantly inhibited at different durations of exposure, no linear relationship between the replication index and the duration of exposure was noticed (r = 0.47, p > 0.05). Similarly, there was no relationship between replication index and SCE frequency (r = -0.36, p > 0.05), suggesting that these two parameters may reflect two different endpoints for the cytogenotoxic effects of styrene oxide.

Regulation of bradykinin-stimulated cation entry into endothelial cells by tyrosine kinase

In endothelial cells, bradykinin stimulates the release of intracellular Ca2+, which is followed by the entry of extracellular Ca2+ into the cells. However, the mechanism underlying the Ca2+ entry is not well understood. To investigate the possible implication of tyrosine kinases in bradykinin-mediated Ca2+ signaling in endothelial cells, cultured porcine aortic endothelial cells were loaded with fura-2/AM, and Mn2+ influx into the cells was determined by the quenching of fluorescence intensity of fura-2 at 360 nm excitation. The tyrosine kinase inhibitors genistein and herbimycin A attenuated not only Ca2+ influx but also Mn2+ influx from the extracellular space without affecting the release of Ca2+ from internal stores in bradykinin-treated cells. In contrast to tyrosine kinase inhibitors, the tyrosine phosphatase inhibitor vanadate stimulated Ca2+ influx as well as Mn2+ influx. On the other hand, both an inactive analog of genistein, daidzein, and an inhibitor of diacylglycerol (DAG) kinase, ethylene glycol dioctanoate, were without effect on [Ca2+]i following the stimulation of agonist. These findings suggest that tyrosine kinase is involved in the regulation of cation influx in endothelial cells.

Roles of inhibitors of myosin light chain kinase and tyrosine kinase on cation influx in agonist-stimulated endothelial cells

Agonist-stimulated Ca2+ influx is critically important to mediate the function of endothelial cells. It has been suggested that release of Ca2+ from internal stores activates Ca2+ influx across the plasma membrane. In the present study, we investigated the effects of ML-9, a myosin light-chain kinase (MLCK) inhibitor, and genistein, a tyrosine kinase inhibitor, on the agonist stimulated Ca2+ response in porcine aortic endothelial cells loaded with a Ca2+-sensitive dye, fura-2. ML-9 almost completely abolished Ca2+ influx, whereas genistein only partially attenuated Ca2+ entry. Both of them did not affect the mobilization of Ca2+ from internal stores. In contrast, genistein was more potent in the inhibition of Mn2+ influx than ML-9. These findings indicate the different selectivity for Ca2+ and Mn2+ in the cation entry pathway in agonist-stimulated endothelial cells.

Death attributed to the toxic interaction of triazolam, amitriptyline and other psychotropic drugs

A 71-year-old man was found dead in a car into which exhaust fumes had been introduced. His wife who was in the same car recovered consciousness following hospitalization. She claimed that they had both attempted suicide by taking a large number of sleeping pills. Autopsy revealed no significant external injuries or medical disorders that would have led to the husband's death. The concentrations of alcohol and carbon-monoxide hemoglobin in his whole blood were 0.26 mg/ml and < 10%, respectively. Therefore, poisoning by carbon monoxide from the exhaust fumes was ruled out, and further toxicological examinations were undertaken. Triazolam, pentobarbital, amitriptyline and bromazepam were all detected in the tissues of the victim; whole blood concentrations were 45.60, 386.4, 521.2 and 166.7 ng/g, respectively. Triazolam (7.350 ng/g) and pentobarbital (288.2 ng/g) were also detected in the whole blood of the wife, collected 17 h after admission to hospital. When evaluating these results in the light of existing literature, we concluded that the victim and his wife had indeed attempted suicide by taking triazolam and pentobarbital. However, only the man had died of triazolam poisoning due to its apparently lethal combination with amitriptyline and other psychotropic drugs which had been prescribed to treat his depression.

Effects of tetrahydroprotoberberines on dopamine D2 receptors in ventral tegmental area of rat

AIM

To compare the actions of tetrahydroprotoberberines (THPB) on dopamine (DA) D2 receptors in the ventral tegmental area (VTA) of rat.

METHODS

Extracellular single unit recording technique was used in i.v. gallamine-paralyzed rats.

RESULTS

Eleven THPB analogs tested completely attenuated the apomorphine (Apo, 20 micrograms.kg-1)-induced inhibition on VTA DA cell firing activity. The OH group on C2 at THPB was linked with the reversal of Apo-induced inhibition. Their reversal potencies (ED50, microgram.kg-1) for D2 receptors were: THPB-143 (5.6) > SPD (8.5) > Iso (17.0) > THP (33) > THB (48) > THPB-18 (66) > THPB-1 (179) > THPB-19 (408) > THPB-126 (510) > THPB-104 (1019) > THPB-10 (4815).

CONCLUSION

Among these 11 THPB, the 2-hydroxyl-THPB (THPB-143) showed the strongest antagonistic action on D2 receptors.

[Blockade of (+/-) 12-chloroscoulerine on feed-back regulation of dopamine D2 autoreceptors]

AIM

To verify whether (+/-) 12-chloroscoulerine (CSL) is antagonist or agonist effect to D2 autoreceptors.

METHODS

The levodopa content accumulated in the rat striatum was measured by HPLC-ECD, and the DA neuron firing activity in the substantia nigra zona compacta (SNC) was recorded.

RESULTS

The accumulated levodopa content induced by CSL 40 mg.kg-1 was much more than that of 1,4-butyro-lactone (BL) group (P < 0.01). After i.p. injection of apomorphine (Apo) 5 mg.kg-1, the levodopa content was decreased below that of BL group (P < 0.05). The Apo inhibition on levodopa content was completely reversed by CSL (40 mg.kg-1, i.p.) and then increased the levodopa content (2.5 +/- 1.1 micrograms.g-1) over that of Apo group (0.7 +/- 0.3 microgram.g-1, P < 0.01). In the electrophysiologic recording, Apo (15 micrograms.kg-1, i.v.) induced the decrease of SNC DA cell firing rate nearly to zero. At the accumulated dose of CSL up to 80 micrograms.kg-1 (i.v.), the inhibition of Apo was attenuated and the firing activity was restored to predrug level.

CONCLUSION

CSL showed an antagonistic action, an action to D2 autoreceptors.

Inhibition of agonist-induced Ca2+ entry in endothelial cells by myosin light-chain kinase inhibitor

Identification of the signal which links the depletion of Ca2+ stores to a Ca2+ entry pathway in the plasma membrane remains to be determined. In the present study, effects of ML-9 and wortmannin, inhibitors of myosin light-chain kinase (MLCK), on agonist-stimulated Ca2+ response were investigated in porcine aortic endothelial cells loaded with the Ca(2+)-sensitive dye fura-2. Bradykinin (BK) caused a rapid increase in [Ca2+]i, followed by a sustained increase due to the influx of Ca2+ from the extracellular space. ML-9 almost completely abolished the sustained increase in [Ca2+]i in BK-stimulated cells, while it did not affect the mobilization of Ca2+ from intracellular stores. ML-9 also abolished the sustained increase in [Ca2+]i caused by thapsigargin. Wortmannin mimicked the effect of ML-9 on the thapsigargin-stimulated Ca2+ response. These findings document for the first time the involvement of MLCK inhibitor in Ca2+ signaling in endothelial cells.

(-)-Stepholidine acts as a D1 partial agonist on firing activity of substantia nigra pars reticulata neurons in 6-hydroxydopamine-lesioned rats

(-)-Stepholidine (SPD), a novel dopamine (DA) D1 and/or D2 receptor antagonist in normosensitive animals, shows agonistic effects on D1 receptors in rotational behavior of 6-hydroxydopamine (6-OHDA)-lesioned rats. To further characterize the pharmacological properties of SPD, we investigated the effects of SPD on firing activity of substantia nigra pars reticulata (SNR) neurons in different sensitive models. In control rats, the selective D1 agonist SKF38393 (4 mg/kg, i.v.) induced inconsistent changes (i.e. increase, decrease or no change) in firing of SNR neurons. These effects were completely antagonized by SPD (i.v.), regardless of the changes induced by SKF38393. SPD (4 mg/kg), per se, increased firing by 30.9 +/- 14.4%. In reserpinized rats, SKF38393 also induced SPD-reversible inconsistent changes as in control rats. Nevertheless, SPD per se produced no alteration in firing of SNR neurons. In 6-OHDA-lesioned rats, 5/6 SNR neurons were inhibited by SKF38393. The inhibition was completely abolished by Sch23390, a selective D1 antagonist (0.5-2 mg/kg), but partially reversed by SPD (1-16 mg/kg). Moreover, SPD (4 mg/kg) itself caused SNR increased or decreased neuron firing, and these effects were completely reversed by Sch23390 (0.5-2 mg/kg) in 8/12 neurons recorded. These results suggest that SPD acts as a partial agonist to D1 receptors in 6-OHDA-lesioned rats, but as an antagonist to D1 receptors in normal and reserpinized rats.

Sensitive determination of bromazepam in human tissues using capillary gas chromatography-mass spectrometry

A reliable and sensitive gas chromatographic-mass spectrometric method was devised to determine the levels of bromazepam in human tissues. Bromazepam was extracted from body tissues using a three-step solvent extraction procedure. N-Desmethyldiazepam served as the internal standard. Selected ion monitoring with m/z 317 for bromazepam and m/z 270 for internal standard was used for quantitation. Calibration curves in all body tissues were linear over the concentration range from 50-500 ng/g. The lower detection limit in body tissues was 2-5 ng/g and the absolute recovery in body tissues was 27.8-68.0%. This method was used to determine the levels of bromazepam in tissues of an autopsied individual who had been prescribed psychotropic drugs and who was found dead in a car.

(-)-stepholidine vs 12-chloroscoulerine enantiomers on firing activity of substantia nigral dopamine neurons

AIM

To compare the potencies between (-)-stepholidine ((-)-SPD) and 12-chloroscoulerine (CSL) enantiomers on firing of substantia nigra (SN) dopamine (DA) neurons.

METHODS

Extracellular single unit recordings in paralyzed rats.

RESULTS

In rats, (-)-SPD, (-)-, ( +/- )-, and (+)-CSL attenuated i.v. apomorphine (Apo, 10 micrograms.kg-1)-induced inhibition on firing of DA cell, and their ED50 values were 15.1 (11.9-19.4), 7.8 (7.0-8.7), 12.6 (2.0-17.9) micrograms.kg-1, and 2.9 (2.6-3.3) mg.kg-1, respectively. Thus, (-)-CSL was 1 time more potent than (-)-SPD and 371 times more potent than (+)-CSL on D2 receptors. In reserpinized rats, (-)-SPD, (-)-, ( +/- )-, and (+)-CSL blocked the inhibition caused by i.v. 4 mg.kg-1 SKF-38393, with ED50 values of 0.53 (0.51-0.55), 0.51 (0.43-0.60), 1.2 (0.7-2.0), and 5.9 (4.9-7.1) mg.kg-1, respectively. The potency of (-)-CSL was similar to that of (-)-SPD on D1 receptors and 11 times higher than that of (+)-CSL.

CONCLUSION

CSL enantiomers are D1/D2 mixed antagonists as (-)-SPD. (-)-CSL is the most, while (+)-CSL is the least, potent one among them.

Effect of desipramine on spontaneous activity of hippocampal CA1 neuron after transient cerebral ischemia in rats

AIM

To study the spontaneous firing of CA1 neurons in rat hippocampus after transient cerebral ischemia and the effect of desipramine (Des) on the post-ischemic electric activity of CA1 neurons.

METHODS

Single-unit extracellular recordings were performed in rats on d 3 after 10 min of cerebral ischemia by occlusion of 4 arteries. Des and saline were injected into a tail vein. The histological changes of CA1 neurons was assessed by the neuronal density of the CA1 sector.

RESULTS

The spontaneous firing rate of CA1 neurons on d 3 after ischemia was enhanced in comparison with the control value. Des (0.2 and 0.4 mg.kg-1, i.v., n = 5 & 6, respectively) reduced dose-dependently the increase of firing rate with maximal inhibition by 6 min (58% & 85%) to 9 min (69% & 94%) (vs vehicle group, P < 0.01). About 50% cells in CA1 region showed necrotic changes.

CONCLUSION

Des antagonized the hyperexcitability of CA1 neurons after cerebral ischemia.

[Studies on function of vegetative nervous system in cardiopathic patients with heart-qi deficiency syndromes and heart-yin deficiency syndromes]

To explore the changes of the function of vegetative nervous system in the patients with the syndromes of Heart-Qi Deficiency (HQD) and Heart-Yin Deficiency (HYD), 53 cases of heart diseases were divided into HQD and HYD, the duration between heart beats, differences of blood pressure in the lying and standing position, and urine-catecholamine/24 hrs was determined separately, and compared with control group. The results showed that the duration between heart beats and heart rate in the lying position in those patients of HQD didn't manifest significant difference with control group. But in 78.9% of patients, the differences of heart rate in expiration/inspiration, surpassed 15 beats per minute, and the proportion of 30/15 was less than 1.03. Compared with control group, the difference was significant (P < 0.01). Meantime, the differences of heart rate of lying/standing position was less than 15 beats per minute, and the difference of blood pressure had an increasing tend in 47.4% of the cases. Those patients of HYD didn't show any difference in the above indexes. Urine-catecholamine/24 hrs in both of the two groups surpassed that of control group (P < 0.01). In short, this study showed that syndromes of HQD and HYD both displayed disturbed function of the vegetative nervous system, and their types and severities were correlated with the difference of Syndromes.

Agonistic actions of pergolide on firing activity of dopamine neurons in substantia nigra compacta area

AIM

To study the potency of pergolide as a D2 receptor agonist on the firing activity of substantia nigra compacta (SNC) dopamine (DA) neurons compared with that of bromocriptine and to determine whether pergolide has the nature of D1 receptor agonist in vivo.

METHODS

Extracellular single unit recording techniques.

RESULTS

Both pergolide and bromocriptine decreased the spontaneously firing rate of "sensitive" and "insensitive" DA cells. In regard of ID50 values, pergolide (11.9, 95% fiducial limits, 5.7-25.1 micrograms kg-1) was more potent than bromocriptine (7.8, 95% fiducial limits, 3.3-18.5 mg kg-1). The discharge inhibition of pergolide was attenuated following the injection of selective D2 receptor antagonist spiperone 0.25 mg kg-1 or selective D1 receptor antagonist Sch-23390 1-2 mg kg-1. However, the inhibition caused by bromocriptine was not always attenuated by spiperone.

CONCLUSION

Pergolide is 650 times more potent than bromocriptine at D2 receptors, and possesses D1 receptor agonist characteristics in vivo.

Technetium-99m N,N'-bis(2-mercapto-2-methylpropyl)-2-aminobenzylamine: technetium-99m complexes of a novel bis(aminoethanethiol) ligand

A new N2S2 ligand system, N,N'-bis(2-mercapto-2-methylpropyl)-2- aminobenzylamine, U-BAT, 1, containing uneven amine groups (two amine groups with different pKa values) for complexing [TcVO]3+, was prepared. The reaction of this novel ligand with [99mTc]pertechnetate, in the presence of stannous tartrate as the reducing agent, produces the neutral and lipid-soluble [99mTc]TcVO(U-BAT), TcS2C15H23N2O, 2. However, when the same reaction was carried out at a higher pH, 9-10, and with 30 min of heating (100 degrees C), a second neutral but more lipid-soluble complex, [99mTc]TcVO(OU-BAT), TcS2C15H21N2O, 3, was isolated. The X-ray crystallography data of the 99Tc complexes show square pyramidal coordination with N2S2 as the base and the Tc = O in the apical position. Compound 3 can be derived from 2 by an oxidation of the ligand to form an imine. After iv injection into rats, the neutral and lipid-soluble technetium-99m complexes showed significant brain uptake, 1.54 and 1.07% dose/organ at 2 min for [99mTc]TcVO(U-BAT) and TcVO(OU-BAT), respectively. The novel Tc chemistry of this new ligand system may provide a useful foundation for designing Tc complexes with a built-in redox mechanism.

Cytogenotoxicity of N-acetyl-S-(1/2-phenyl-2-hydroxyethyl)-cysteine (NAPEC) in cultured human blood lymphocytes

N-Acetyl-S-(1/2-phenyl-2-hydroxyethyl)-cysteine (NAPEC) is a cysteine conjugate derived from the glutathione conjugate of styrene oxide. The dose- and time-dependent effects of NAPEC on SCEs and cell kinetics were studied in cultured human blood lymphocyte in vitro. Different concentrations of NAPEC (0-1500 microM) were added into the lymphocyte cultures. After 36 h of exposure, both the induction of SCEs and cell-cycle delay were increased with increasing concentrations of NAPEC. When the lymphocyte cultures were exposed to 1000 microM NAPEC for 22, 36 and 72 h during a total of 72-h culture period, no significant differences in the induction of SCEs or cell-cycle delay were noticed due to 3 exposure times. These results suggest that NAPEC possesses the potential to induce SCEs and to inhibit cell-cycle progression and such potential seems to be independent of duration of exposure to NAPEC.

Ciliary neurotrophic factor is an endogenous pyrogen

Fever is initiated by the action of polypeptide cytokines called endogenous pyrogens, which are produced by the host during inflammation, trauma, or infection and which elevate the thermoregulatory set point in the hypothalamus. Ciliary neurotrophic factor (CNTF) supports the differentiation and survival of central and peripheral neurons. We describe the activity of CNTF as intrinsically pyrogenic in the rabbit. CNTF induced a monophasic fever which rose rapidly (within the first 12 min) following intravenous injection; CNTF fever was blocked by pretreatment with indomethacin. The fever induced by CNTF was not due to contaminating endotoxins. Increasing doses of CNTF resulted in prolongation of the fever, suggesting the subsequent induction of additional endogenous pyrogenic activity. After passive transfer of plasma obtained during CNTF-induced fever, endogenous pyrogen activity was not present in the circulation; CNTF also did not induce the endogenous pyrogens interleukin 1, tumor necrosis factor, or interleukin 6 in vitro. Nevertheless, a second endogenous pyrogen may originate within the central nervous system following the systemic injection of CNTF. Of the four endogenous pyrogens described to date (interleukin 1, tumor necrosis factor, interferon, and interleukin 6), CNTF, like interleukin 6, utilizes the cell-surface gp 130 signal-transduction apparatus.

Effects of different styrene metabolites on cytotoxicity, sister-chromatid exchanges and cell-cycle kinetics in human whole blood lymphocytes in vitro

5 metabolites of styrene were tested in vitro for their cytotoxic effects, induction of SCEs and changes in cell-cycle progression in cultured human blood lymphocytes. Fresh heparinized peripheral blood (0.3 ml) from normal volunteers was cultured for a total of 72 h in 5 ml of RPMI 1640 medium containing 10% fetal calf serum, 0.1% garamycine, 1% glutamine and 1% phytohaemagglutinin. Styrene-7,8-oxide (SO), styrene glycol (SG), phenylglyoxylic acid (PGA), S-[1,2-phenyl-2-hydroxyethyl]-glutathione (PEG) (a glutathione conjugate of styrene oxide), N-acetyl-S-[1,2-phenyl-2-hydroxyethyl]-cysteine (NAPEC) in dimethyl sulfoxide (DMSO) were injected into the cultures 36 h after initial culture, so that the exposure time for these metabolites was 36 h. The final concentration of SO was 100 microM and those of the other metabolites were 500 microM. 24 h before harvest, BrdU (10 micrograms/ml) was added into the cultures for assessing cytogenetic endpoints. SO showed significant induction of SCEs and cell-cycle delay as well as a significant decline of cell survival. The same phenomena, but of less magnitude, were also observed with NAPEC, a cysteine derivative of SO. On the other hand, SG, PGA and PEG failed to produce any significant changes of these endpoints compared to the control. Thus, the present results have demonstrated that, in addition to SO, NAPEC possesses some cytogenotoxic potential and hence, these two metabolites together could contribute to the genotoxicity of styrene in human blood lymphocytes.

[An investigation on the freshwater crab as the host of Paragonimus in Hunan province]

Through an investigation of the freshwater crabs in 39 counties of Hunan province, 20 species of fresh water crabs were found as the intermediate hosts of Paragonimus. They belong to three genus and two families, in which 10 are new species (including 4 new subspecies). Besides, the natural infection with lung fluke metacercariae was also observed in some of the fresh water crabs.

Cytogenetic effects of low-level exposure to toluene, xylene, and their mixture on human blood lymphocytes

The present study was undertaken to investigate, both in vitro and in vivo, the genotoxic potential of short-term low-level exposure to toluene, xylene, and their mixture, for which information is limited at the present time. Five adult healthy white men were exposed for 7 consecutive hours per day over 3 consecutive days to 50 ppm toluene and 40 ppm xylene either alone or in combination in a controlled exposure chamber. Such an exposure was repeated three times at intervals of 2 weeks. Blood samples were taken before and after the termination of such exposure. Three different cytogenetic end-points were evaluated using peripheral blood lymphocytes: number of sister chromatid exchanges (SCEs), cell cycle delay, and cell mortality. No significant effects on SCEs, cell cycle delay, and cell mortality were observed following such exposure to toluene or xylene or their mixture. Similarly, exposure of human blood lymphocytes in vitro to either toluene (0-2.5 mM) or xylene (0-2 mM) or their mixture for 72 h did not result in any significant cytogenetic effects at lower concentrations, while at higher concentrations, only cell mortality was found to be significantly affected. Thus our present study indicates that simultaneous exposure to low levels (within the admissible limits) of toluene, xylene, or their mixture for a short period does not pose any potential mutagenic threat to humans.

Effect of ocular chromatic aberration on monocular visual performance

This brief review outlines the theory of ocular chromatic aberration and describes the three primary forms in which the aberration appears: chromatic difference of focus, chromatic difference of magnification, and chromatic difference of position. Our central theme is that all three aspects of chromatic aberration have as their common basis the chromatic dispersion of light. The magnitude of each form of the aberration is related to the others by simple linear formulas in which a key parameter is the location of the pupil relative to the nodal point of the eye. The way in which retinal image quality is affected by chromatic aberration is described and we assess the impact of the aberration on visual performance.

Achromatizing the human eye

Ocular chromatic dispersion manifests itself as wavelength-dependent image planes, image sizes, and image positions, and it has been suggested that ocular chromatic aberration is the most important of the eye's optical aberrations. Most attempts to correct for the eye's chromatic aberration (achromatize the human eye) have concentrated on correcting the wavelength-dependent image planes or chromatic difference of refractive error (CDRx). There are two optical techniques that correct for CDRx (special achromatizing lenses and multiple channel display systems) by making the ocular image planes of all wavelengths coincident. A different approach simply avoids the effects of ocular CDRx by using small pupils which effectively make all images diffraction-limited irrespective of wavelength-dependent differences in image planes. Theoretical and experimental evidence shows that achromatizing lenses provide an accurate correction for CDRx. In spite of the pre-eminence of chromatic aberrations, and the effectiveness of the corrections, no obvious improvements in vision accompany correction. We show that loss of retinal image quality due to CDRx may be subthreshold (less than ocular depth of focus). We also show that achromatizing methods can introduce their own chromatic aberrations that can easily exceed those present in the uncorrected eye. The precise location of the eye with respect to the achromatizing device determines the amount of these additional aberrations. Therefore, in order to achromatize the eye effectively, careful control of eye position is essential.

Relation between the chromatic difference of refraction and the chromatic difference of magnification for the reduced eye

We provide a simple model for calculating the chromatic difference of magnification for the human eye. Spectral differences in image size are proportional to the eye's longitudinal chromatic aberration and the axial distance between the entrance pupil and nodal point. We verify that the model provides magnification estimates equal to previously published predictions, and we show the significant increase in this aberration produced by experimental use of artificial pupils.

Achromatizing the human eye: the problem of chromatic parallax

Attempts to correct the chromatic difference of focus of the human eye will introduce unwanted chromatic parallax if the eye is misaligned with the optical axis of the achromatizing system. Using geometrical optics, we show that the amount of parallax is approximately proportional to the amount of misalignment of the eye, with the constant of proportionality equal to the eye's chromatic difference of refractive error. This prediction was confirmed by the experimental determination of chromatic parallax for two commercially available achromatizing lenses. On the basis of these results, we calculated that anticipated improvements in the polychromatic modulation transfer function of the eye offered by achromatizing lenses will be canceled by approximately 0.4 mm of the misalignment between the lens and the eye. Our prediction that further misalignment would severely reduce image quality of the achromatized eye was verified by psychophysical measurements of contrast sensitivity.

Interocular differences in transverse chromatic aberration determine chromostereopsis for small pupils

Chromostereopsis has been attributed previously to interocular differences in foveal transverse chromatic aberration (TCA). We tested this hypothesis by measuring chromostereopsis as a function of the separation of small artificial pupils. We also measured the monocular transverse chromatic aberration under the same conditions. Our results show that chromostereopsis with small pupils can be precisely accounted for by the interocular difference in monocular transverse chromatic aberration. This relationship is closely predicted by a simple water eye model.

Isolation and characterization of a molecular cDNA clone of a human mRNA from interferon-treated cells encoding nucleolar protein B23, numatrin

A cDNA clone encoding human nucleolar phosphoprotein B23, numatrin, was isolated from a library prepared with mRNA from human U cells. The complete nucleotide sequence was determined; it revealed a single open reading frame of 294 amino acids that included four in-frame AUG codons as potential sites of translation initiation. Comparison of the human B23 nucleotide sequence with the rat and mouse B23 sequences revealed 91% homology (hum:rat, and hum:mus) in the coding region; the predicted B23 proteins displayed 94% amino acid identity. Northern gel blot analysis revealed a single B23 mRNA species of approximately 1.5 kb. The level of B23 mRNA in U cells was not detectably altered by treatment with either alpha or gamma interferon. Southern gel blot analysis revealed polymorphism within the human B23 gene structure, and suggested the presence of multiple B23 genes and/or extensive splicing of B23 RNA transcripts.

Does the chromatic aberration of the eye vary with age?

The longitudinal chromatic aberration of the eye has been reported to decline with age. Using three different methods, we have measured the aberration in a group of young subjects (27-33 years old) and a group of older subjects (48-72 years old). In two of the methods we used a Badal optometer, either with or without an achromatizing lens incorporated, to examine the effect of wavelength on refractive error. In the third method we used a vernier-alignment apparatus to assess chromatic dispersion directly. None of the results of the experiments performed revealed any difference in aberration between the groups. Furthermore, a linear regression of aberration against age showed no relationship between these variables. We conclude that, for human adults, the magnitude of chromatic aberration is independent of age.