[Studies on the toxicity of a new synthetic drug SC1001-aminum]

SC1001A is a new sedative, hypnotic and anti-epileptic drug. Screening for possible mutagenicity of the agent consisted of a battery scheme of short-term mutagenic tests with different hereditary detecting end points. Three assays were with in the scheme: Ames test (for detecting gene mutation in vitro), micronucleus test (for detecting chromosomal aberration in vivo) and CHL (Chinese hamster lung cell line) test (for detecting chromosomal aberration in vitro). In addition, a routine teratogenicity study on SC1001A was carried out in mice. They were given daily at 3-dose levels (exposed to up to 33% of the LD50 by gastric incubation from the 6th through the 15th day of gestation. SC1001A gave uniformly negative results in all three mutagenic assay systems. Results of the teratogenic experiment showed that only the pregnant rate in bred mice in the moderate dose group and the mean maternal body weight gain of the dams during gestation in the low dose group were significantly lower than those in the corresponding control group. A clear dose-response relationship was not demonstrated. All dose levels of SC1001A used caused no adverse effects on the number of survival fetuses per litter, growth or development of the fetal mice. No malformations in the external appearance, of the internal organs and of the skeletal systems in fetal mice were observed. The above-mentioned results indicated that SC1001A induced neither gene mutation nor chromosomal damage both in vitro and in vivo. There was no evidence of teratogenesis. Therefore, it is estimated that SC1001A is probably comparatively safe as a pharmaceutical product for human beings in usual dosage.

[Studies of the determination of selenium by hydride generation atomic absorption spectrometry]

Potassium ferricyanide has a masking effect of Cu2+, Ni2+ and other interferential ions in the determination of selenium by hydride generation atomic absorption spectrometry. Interference was not observed in the determination of 5ng/ml of Se(IV) in the presence of 10micrograms/ml of Cu2+ under recommended conditions. The stability of analyte and potassium borohydride solutions in storage was also studied.

[Prevention and treatment of emphysema in the guinea pig with ligustrazine]

This study demonstrated that ligustrazine possesses inhibitory effect obviously on elastic enzyme in vitro, and it can be used to prevent and treat emphysema instead of serum. Using light microscope and electron microscope, the authors observed morphological indexes and analyzed the indexes with stereology and statistics in lung tissues of guinea pigs. The results showed that there was no obvious difference between the ligustrazine administration group and the saline control group as pathological changes were not found in the ligustrazine administration group under microscope. The shapes of elastic proteins were the same under electron microscope observation. Aerosol inhalational method induced emphysema model of elastic enzyme in guinea pig could be improved with ligustrazine treatment.

[Anti-inflammatory effect of aconitines]

Aconitines are the total alkaloids isolated from the main root of Aconitum carmichaeli. They have marked suppressive effect on the swelling of rat's hind paw induced by injections of fresh egg protein, carrageenin, histamine and 5-HT, on the mouse's ear oedema induced by bimethylphenyl, on the exudate and proliferation of granulation tissue of granuloma pouch induced by croton oil, on the leukocyte migration and on the contents of PGE in the exudate of the swelling hind paw induced by injecting carrageenin. Aconitines have been found useful in inhibiting significantly such immune inflammations as reversible passive Arthus reaction, rat's delayed skin hypersensitivity and adjuvant arthritis. They have also a noticeable analgesic effect.

Components of high-level vision: a cognitive neuroscience analysis and accounts of neurological syndromes

Neuroanatomical, neurophysiological, and computational constraints are used to motivate a set of hypotheses about the functional organization of high-level vision. A set of processing subsystems is posited that underlies the later stages of visual object recognition and identification; these subsystems have been implemented in a running computer simulation model. The model is damaged in a variety of ways, and its performance on a set of tasks is observed. Dysfunctions arise from disruptions of the subsystems, disruptions of their interconnections, compensations by intact subsystems, and diminished activational capacity. The most common dysfunctions of high-level vision following brain damage are then reviewed, and accounts are offered by reference to the stimulation model. According to the theory and model, each type of dysfunction can arise from numerous underlying causes, all of which are potentially distinguishable by empirical methods.

Sodium channel comodification with full activator reveals veratridine reaction dynamics

Veratridine association and dissociation rates were determined at single sodium channels in outside-out patches of cultured ventricular myocytes obtained from late-fetal rat hearts. In single cardiac sodium channels depolarized from -110 to -30 mV, intracellular veratridine induced a long lasting (tau = 0.48 sec) open state with small current amplitude (-0.3 pA, i.e., 1/4 of normal) and frequent closing transitions, giving it a burstlike appearance, in agreement with reports on other types of sodium channel. Veratridine-associated and veratridine-free states of a single sodium channel were monitored by comodifying it with an allosteric activator, BDF 9145 (1 microM), that induced a burst with normal open channel current amplitude (-1.2 pA at -30 mV) upon veratridine dissociation. Veratridine and BDF 9145 interacted with reciprocal synergism at the single sodium channel such that veratridine-induced bursts (called P-bursts for partially activated) alternated with BDF 9145-induced bursts (called F-bursts for fully activated) many times following a single depolarization to -30 mV. P-bursts and F-bursts within such trains of bursts had exponentially distributed durations. The reciprocal time constant for F-bursts, tau F-1, increased linearly with veratridine concentration (0.3-30 microM), whereas tau P was insensitive. We conclude, therefore, that P-bursts reflect veratridine occupancy and F-bursts reflect the veratridine-free state; if veratridine and BDF 9145 bind to a sodium channel simultaneously, veratridine exerts conformational dominance, i.e., retains its property to reduce channel conductance. For the single cardiac sodium channel activated (i.e., deprived of inactivation) by BDF 9145, we have determined a veratridine association rate constant k1 = 4.3 x 10(6) M0-1 sec-1, dissociation rate constant K-1 = 2.2 sec-1 and equilibrium dissociation constant KD = 5.1 x 10(-7) M (20 degrees, -30 mV membrane potential).

Absence of antibody to human immunodeficiency virus in long-term, socially rehabilitated methadone maintenance patients

Human immunodeficiency virus (HIV) infection has become widespread among parenteral drug abusers. We measured antibody to HIV and hepatitis B virus markers in 58 long-term, socially rehabilitated methadone-maintained former heroin addicts. None of the 58 had antibody to HIV, but one or more markers of hepatitis B virus infection were seen in 53 (91%). The duration of methadone maintenance was 16.9 +/- 0.5 years, and the median dose of methadone was 60 mg (range, 5 to 100 mg). Before methadone treatment, the patients had abused heroin parenterally for 10.3 +/- 1.7 years, and they had engaged in additional high-risk practices for HIV infection. We conclude that successful outcomes during methadone maintenance treatment are associated with sparing of parenteral drug abusers from HIV infection.

Interaction between DPI 201-106 enantiomers at the cardiac sodium channel

The modification of cardiac sodium channels by DPI 201-106, its S-enantiomeric form (S)-DPI, and its R-enantiomeric form (R)-DPI was investigated with whole-cell voltage-clamp recording in single cultured ventricular myocytes obtained from late-fetal rats. From a holding potential of -100 mV, depolarizing pulses to -30 mV of 50-msec duration were applied at 0.2 Hz. Extracellular [Na] was reduced to 70 mM; temperature was 20 degrees. Drugs were administered directly on the cell by a double-barrelled microsuperfusion system. Sodium current inactivation was progressively slowed when the concentration of DPI 201-106 was increased from 0.3 to 3 microM. At 10 microM DPI 201-106, this effect was followed by a blocking effect on peak inward sodium current (INa), and at 30 microM inward sodium current was fully blocked within 2 min. The slowing of inactivation was produced by (S)-DPI (maximally effective at 3 microM), whereas (R)-DPI had little effect on inactivation at 3 microM. Conversely, (R)-DPI reduced INa at 10 microM, whereas (S)-DPI did not reduce INa at 3 microM. The effects of both (S)-DPI and (R)-DPI were partially reversed by washout. (R)-DPI retained its blocking activity on INa when the interval between depolarizing pulses was prolonged to 90 sec. In order to test whether the different sodium channel modifications produced by (S)-DPI and (R)-DPI were mutually exclusive, the INa-reducing activity of (R)-DPI was measured in the absence of (S)-DPI and after equilibration with a maximally effective (S)-DPI concentration. In the absence of (S)-DPI, 3 microM (R)-DPI reduced INa by 35% and in the presence of 3 microM (S)-DPI, by 51%. Thus, modification by (S)-DPI of sodium channels did not prevent their block by (R)-DPI. The INa-reducing activity of (R)-DPI was even significantly augmented by (S)-DPI after a 1-sec depolarization to -30 mV. During such prolonged pulses, (R)-DPI accelerated the monoexponential decay of the (S)-DPI-induced slow phase of sodium current inactivation. The results are consistent with an irreversible binding reaction between (R)-DPI and (S)-DPI-modified open sodium channels (association rate constant, 4.7 x 10(5) M-1sec-1). We conclude that (R)-DPI reduces INa by interacting both with resting sodium channels and with (S)-DPI-modified open sodium channels. The corresponding receptor site is stereoselective and distinct from and allosterically coupled to the (s)-DPI receptor that mediates slowing of inactivation.(ABSTRACT TRUNCATED AT 400 WORDS)

Coordination chemistry and the carcinogenicity and mutagenicity of chromium(VI)

Chromate is a known carcinogen, it is only in recent years that the molecular mechanisms by which this toxicity may be expressed have been investigated. The toxicity of chromate may be mediated by the reaction of chromium(VI) with glutathione (GSH) to generate relatively stable chromium(V) complexes and other more reactive intermediates. The conditions favouring the formation of such complexes have been studied. Reactive intermediates generated during the reduction of chromate by GSH include thionyl radicals and at least two relatively stable chromium(V) species (g -1.996 and g -.986). Mixtures of chromium(VI) and glutathione and a chromium(V) complex of glutathione, which we have isolated from the reaction (g = 1.996), are capable of causing strand breaks in bacteriophage PM2 DNA. In contrast a chromium(III) complex of GSSG, one of the final products of the reaction between GSH and chromium(VI), does not damage DNA in closed circle assays. These observations support the suggestion that reactive intermediates generated during the reduction of chromium(VI) provide one route by which the genotoxicity of chromate may be expressed.

Hydrocortisone promotes survival and proliferation of granulocyte-macrophage progenitors via monocytes/macrophages

We have determined the mechanism by which hydrocortisone (Hc) promotes the survival and proliferation of normal human granulocyte-macrophage progenitors (granulocyte-macrophage colony-forming units, CFU-GM). Peripheral blood mononuclear cells were cultured in a liquid system with 0-10.0 microM Hc over 3 weeks. At 7-day intervals 50% of the culture media along with the cells (suspension cells) present in the media were removed and replaced with fresh media. No CFU-GM or very small numbers of CFU-GM were contained in the suspension cells of the 14- and 21-day-old liquid cultures without Hc; CFU-GM were present and increased with increasing concentrations of Hc. The CFU-GM content in suspension cells of 14- and 21-day-old liquid cultures with 1.0 microM Hc was at least threefold higher compared to liquid cultures without Hc. In a double-layer CFU-GM agar culture system, the suspension cells from liquid cultures with 1.0 microM Hc, but not from liquid cultures without Hc, supported CFU-GM proliferation from normal human bone marrow cells. The CFU-GM proliferation-inducing ability was confined to the monocytes/macrophages (Mo). CFU-GM colony inhibitory and stimulatory activities were detected in cell-free media recovered from liquid cultures without Hc, but only colony stimulatory activity was detected in the media from cultures with 1.0 microM Hc. These results indicate that greater than or equal to physiological concentrations of Hc (0.1-1.0 microM) are required for the persistence and proliferation of CFU-GM, and the effect of Hc is mediated through the Mo, probably by inhibiting the production of one or more of the CFU-GM colony inhibitory molecules.

Surgical treatment of 100 patients with W-P-W syndrome

100 patients with W-P-W syndrome who had repeated attacks of supraventricular tachycardia (200-300 beats per minute) associated with syncope and hypotension were treated surgically. Most of them were refractory to medical treatment. Electrophysiological studies were done before operation and the anomalous conduction pathways (ACPs) were confirmed and localized by epicardial mapping during the operation. Among the 100 patients, 44 were of type B, 29 type A and 27 type A + B. The right ACPs were excised and the left ACPs were injected with alcohol. Four patients died after operation. 96 patients were followed up for an average of 24 months; 38 (90.5%) of 42 type B patients, 23 (82.1%) of 28 type A patients, and 17 (65.4%) of 26 type A + B patients were cured.

Enrichment of the spindle fiber attachments from mouse liver cell nuclei

Spindle fiber attachments (SFAs) were enriched in a fraction of nuclei isolated from mouse livers. The enrichment method combines sonication, treatment with 2 mol/L NaCl and high speed centrifugation. SFA was enriched 27-fold on the average (n = 4) when measured by radioimmunoassay. The basic method offers opportunities for further increases of yield and for the enrichment of SFA of other vertebrates.

Progressively restricted expression of a homeo box gene within the aboral ectoderm of developing sea urchin embryos

A homeo box-containing gene, Hbox1 is expressed in an unusual and highly conserved spatial pattern in embryos of two different species of sea urchin, Tripneustes gratilla and Strongylocentrotus purpuratus. Hybridization in situ shows that this mRNA accumulates initially throughout the aboral ectoderm; however, between blastula and pluteus stages, the region containing Hbox1 mRNA retracts gradually until only a small area around the vertex is labeled in pluteus larvae. Aboral ectoderm appears cytologically uniform and also accumulates uniform levels of other tissue-specific mRNAs. Therefore, the Hbox1 pattern reveals a previously unsuspected heterogeneity of aboral ectoderm cells and a polarity within this tissue. In S. purpuratus, the Hbox1 gene product probably is not involved in initial specification of cell fate, as this message does not achieve a significant fraction of its peak abundance until almost hatching blastula stage, well after the time aboral ectoderm cells have initiated a tissue-specific program of gene expression. RNA blot and RNase protection analyses revealed low levels of Hbox1 mRNA in all adult tissues examined. However, this message was not detectable in mature eggs, suggesting that the Hbox1 gene does not have a maternal function. In addition to highly conserved spatial and temporal patterns of expression, the homeo box genes of these two urchin species also are conserved highly in sequences outside the homeo domain, despite the divergence of these two species (30-45 my). Two notable features of the protein shared with several vertebrate homeo proteins are a short conserved sequence encoded by an exon upstream of that encoding the homeo domain and a large region of high serine and proline content.

Stage- and tissue-specific expression of two homeo box genes in sea urchin embryos and adults

We report the isolation of two different homeo box genes, HB3 and HB4, from the Hawaiian sea urchin Tripneustes gratilla. DNA sequencing revealed a definitive Antennapedia (Antp) class homeo box in each gene. Southern transfer hybridizations showed the genes to be single-copy. A 5.7-kb transcript of the HB3 gene was found in ovary, testis, small intestine and gastrula poly(A)+ RNA. The HB4 gene produces three transcripts. A 3.7-kb and a 4.4-kb transcript are expressed during embryogenesis. A 3.5-kb transcript appears in each of the adult tissues studied. The HB4 gene appears to be the sea urchin cognate of the Drosophila infrabdominal-7 (iab-7) gene, the mouse Hox 1.7 and Hox 3.2 genes and the Xenopus X1Hbox 6 gene. An examination of Antp class homeo box genes in deuterostomes indicates that a chromosomal duplication has taken place in the evolutionary line leading to the vertebrates after the divergence of the echinoderms. Thus, the sea urchin represents the primitive condition.