The effects of dietary soybean versus skim milk protein on plasma and hepatic concentrations of zinc in veal calves

We assessed the zinc status of veal calves that were fed milk replacers containing either skim milk protein as the sole source of protein or a mixture of skim milk protein and soybean protein. After the milk replacers had been fed for 26 wk, mean body weight gain was 3 kg lower for calves fed the skim milk plus soybean proteins; this decrease was not significant. Inclusion of dietary protein from soybeans versus milk protein alone reduced plasma concentrations of zinc by 43% and reduced hepatic concentrations of zinc by 81%. The impairment of zinc status that was induced by the inclusion of soybean protein was probably caused by its phytate component. The effect of soybean protein on zinc status was rather specific because plasma and hepatic concentrations of copper were unaffected. Despite the high concentration of zinc (142 mg/kg of dry matter) in the milk replacer that contained milk plus soybean proteins, calves displayed a shortage of zinc because their plasma and hepatic concentrations of zinc were significantly reduced.

WIN 35,428 and mazindol are mutually exclusive in binding to the cloned human dopamine transporter

It has been suggested that cocaine and mazindol bind to separate sites on the dopamine transporter. In the present study, we address this issue by examining the inhibition by mazindol of the binding of [3H]WIN 35,428 ([3H]2beta-carbomethyoxy-3beta-(4-fluorophenyl)-tropane), a phenyltropane analog of cocaine, and the inhibition by WIN 35,428 of [3H]mazindol binding to the cloned human dopamine transporter expressed in C6 glioma cells. The design involved the construction of inhibition curves at six widely different radioligand levels, enabling the distinction between the nonlinear hyperbolic competition (i.e., negative allosteric) model and the competitive (i.e., mutually exclusive binding) model. Nonlinear computer curve-fitting analysis indicated no difference in the goodness of fit between the two models; the negative allosteric model indicated an extremely high allosteric constant of approximately > or = 100, which practically equates to the competitive model. The present results suggest that complex interactions reported between cocaine and mazindol in inhibiting dopamine transport are beyond the level of ligand recognition.

Identification of Candida species by randomly amplified polymorphic DNA fingerprinting of colony lysates

We have characterized a method that produces simple yet diagnostic fingerprints that are unique to isolates of Candida species. DNA from individual colonies can be amplified from crude single-colony lysates. Randomly amplified polymorphic DNA (RAPD) fingerprints generated from a single primer correctly identified the species of most (>98%) of the isolates identified with CHROMagar Candida plates as non-Candida albicans Candida species. RAPD fingerprints were much more informative than the plates, since they distinguished between all tested species and required less time. Most (91%) of these identifications agreed with those assigned by API 20C tests. In almost every incident of species identity mismatch, electrophoretic karyotyping showed that the RAPD fingerprint was correct. This underscores the improved objectivity and reliability of this method over those of conventional diagnostic tools. The identities of approximately 30% of C. albicans isolates identified in clinical laboratories by positive germ tube tests are not verified by either testing on CHROMagar Candida plates or RAPD fingerprinting. Data suggest that clinical isolates conventionally identified as C. albicans in clinical settings are heterogeneous, consisting of both misidentified and atypical yeasts. RAPD fingerprints obtained from primary culture plate colonies allows for rapid, highly accurate determinations of Candida species, hence permitting earlier selection of appropriate antifungal agents in the clinical setting.

The correlation of Ureaplasma urealyticum infection with infertility

A prevalence study of Ureaplasma urealyticum (UU) infection of the male genital tract was carried out in Shanghai between March 1992 and June 1995. Significantly higher frequency of UU infection was found among infertile males (549/1416) as compared to fertile controls (34/375). Examination of 8 specimens each from infertile men and fertile subjects by electron microscopy, immunogold and immunofluorescence techniques, demonstrated adhesion of Ureaplasma urealyticum to the membrane of spermatozoa and exfoliated germ cells. In addition, gold particles on Ureaplasma urealyticum were found to be adhered to the sperm surface in 4 of the 8 samples. Strong specific anti-UU fluorescence was detected in 6 of 8 samples, mainly on the midpieces and post-acrosomal regions of the spermatozoa. To further study the effects of Ureaplasma urealyticum on fertility, 47 male Sprague-Dawley (SD) rats were infected artificially with Ureaplasma urealyticum serotype 8 (T960). Morphological changes in the seminiferous tubules were observed 3-5 weeks after inoculation in the sacrificed animals. Dramatic impairment of spermatogenesis of both testes was found in 11 rats. Mating experiment confirmed infertility in 12 of 40 rats. Offsprings of the infected rats were significantly smaller than those of controls in terms of prenatal weights and birthweights.

Dimerization is essential for DNA binding and repression by the ArsR metalloregulatory protein of Escherichia coli

Arsenical resistance (ars) operons produce resistance to trivalent and pentavalent salts of the metalloids arsenic and antimony in cells of Escherichia coli. The first gene in the operon, arsR, was previously shown to encode a homodimeric trans-acting metalloregulatory repressor protein. Dimerization of ArsR was investigated using the yeast two-hybrid system in which the ArsR protein was fused to the Saccharomyces cerevisiae GAL4 DNA-binding domain and GAL4 activation domain to produce chimeric proteins. Transcriptional activation of lacZ reporter indicated that dimerization of the ArsR is stable in yeast. The results indicated that residues 1-8 and 90-117 are not required for ArsR dimerization. The genes for a series of truncated ArsR proteins containing six histidine tags were constructed and the proteins purified. The mass of each recombinant protein, as determined by size exclusion chromatography, was consistent with the results from two-hybrid analysis. The results of beta-galactosidase assays in vivo and gel mobility shift assays in vitro showed that dimers retained the ability to bind to the ars promoter and to respond to inducer, whereas monomeric ArsRs did neither. These results suggest that a core sequence of about 80 residues has all of the information necessary for dimerization, repression, and metal recognition.

Stress response of lysosomal cysteine proteinases in rat C6 glioma cells

Acid proteinases of C6 rat glioma cells were analyzed by means of gelatine polyacrylamide electrophoresis with respect to their responses to stress (heat shock and butanol). Proteinase activities on gelatine gels were characterized by their molecular masses. pH-optima, isoelectric points and reactions to inhibitors. Four bands of 25, 35 and 65/85 kDa most probably represent active and proforms as well as precursor complexes of lysosomal cysteine proteinases with pH optima between 4.0 and 5.0. The 25-kDa band seems to contain cathepsin L and B, the 35-kDa band proforms of cathepsin L and B and the 65/85-kDa bands possibly precursor complexes of cathepsin L and B. After 30-min heat shocks of different temperatures (40-50 degrees C), the 35-kDa activity increased, whereas the 65/85-kDa activity decreased after exposure to 42 and 44 degrees C, which also caused a strong increase in the level of the inducible heat shock protein of 68 kDa (HSP 68). The alterations of the proteinase activities and the increases of the HSP 68 levels occur at heat shock treatments that cause cell death in about 25-40% of the population as determined by Trypan blue staining. HSP 68 induction and proteinase activity changes were also observed 12 hr after a 1-hr treatment with different butanol concentrations (0.14-0.16 M). Kinetics of the response to a 30-min heat shock (44 degrees C) revealed a maximal decrease of the 35-kDa and a maximal increase of the 65/85-kDa activities after 12 hr recovery. When cells were exposed to repeated heat shocks (44 degrees C) at 12-hr intervals, the HSP 68 level further increased, whereas the 35-kDa and 65/85-kDa proteinase activities did not change. This result indicates a role of HSP 68 (or other HSPs) in the processing or stability of the putative cathepsin precursors (65/85-kDa complexes).

Experimental study on biodynamic response to vibration in human and animals

In order to study the characteristics of human dynamic response to vibration, 56 subjects were exposed to vibration on X, Y and Z axes. It showed that there were two resonance peaks of most local parts of the human body. The curves of transmissibility are essentially the same in all the subjects. It was found that resonance frequencies of the human body decreased with increase of G levels of vibration. These characteristics were also proved in animals. Using three-level artificial neural network, common reflective relation of the resonance frequency with height and weight of the human body and exciting acceleration were obtained. The above findings might be applicable to studies of vibration ergonomics.

Multiphoton-excited visible emission by serotonin solutions

Nonlinear excitation of the neurotransmitter serotonin (5HT) in aqueous solution is shown to generate a blue-green-emitting photoproduct in addition to UV fluorescence characteristic of native 5HT. The visible emission rate in diffusional steady-state measurements scales as the sixth power of excitation intensity, demonstrating that absorption of six near-IR photons is required to generate emission of one visible photon. Transient measurements reveal that this process is composed of two sequential nonlinear steps, the first excited by four photons and the second by two photons. These results, in combination with measurements of multiphoton-excited serotonin UV fluorescence, support a model in which 5HT is photochemically transformed as a consequence of four-photon absorption (Etot approximately 6 eV) to a photoproduct that then emits in the visible region via two-photon excitation. A minimum bound of approximately 10(-51) cm4 s photon-1 is observed for the two-photon emission action cross section at 830 nm. Photoionization, rather than reaction with a dissolved oxygen species, appears to be the primary mechanism for generation of the blue-green-emitting photoproduct. The peak intensities required to generate significant blue-green emission (approximately 5 x 10(11) W cm-2 from 80 MHz 150 fs titanium: sapphire laser pulses) are approximately five-fold higher than are typically used in two-photon laser scanning microscopy but are still substantially lower than the estimated intensity needed to induce dielectric breakdown of water.

Pharmacology and regulation of the neuronal dopamine transporter

The dopamine transporter, a member of the family of Na+,Cl(-)-dependent transporters, mediates uptake of dopamine into dopaminergic neurons by an electrogenic, Na(+)- and Cl(-)-transport-coupled mechanism. Dopamine and blockers of uptake such as cocaine probably bind to both shared and separate domains on the transporter, which can be influenced dramatically by the presence of cations. Regulation of the dopamine transporter occurs both by chronic occupancy with blocker and by acute effects of D2 dopamine receptors or second messengers such as diacylglycerol (protein kinase C) and arachidonic acid. The dopamine transporter is involved in the uptake of toxins generating Parkinson's disease; it is also an important target for psychostimulant drugs, ligands for in vivo imaging and medications used for neurologic diseases involving changes in the dopamine system.

[The role of insulin resistance in the clustering of cardiovascular risk factors]

The coexistence of multiple cardiovascular risk factors in the same individual is called a clustering of cardiovascular risk factors. Many studies have shown that this phenomenoa is associated with a increased morbility of cardiovascular disease, and insulin resistance may be the common link between the risk factors. This study was designed to link the clustering of cardiovascular risk factors with insulin resistance. Using a new insulin sensitivity index [-log (fasting serum Glu x Ins)] to evaluate the insulin resistance, we investigated the relationship between the insulin sensitivity and cardiovascular risk factors in 106 patients with hypertension or coronary heart disease and 32 normal subjects. The normal group without cardiovascular risk factors was selected as controls. The individual with 2 risk factors were defined as having mild clustering, and those with > or = 3 risk factors as severe clustering. As the number of risk factors increased from 1 to > or = 3, the insulin sensitivity index increased from -1.69 +/- 0.24, -1.95 +/- 0.17 to -2.14 +/- 0.21 respectively. The insulin resistance was positively correlated with serum uric acid in women (P < 0.05), but not in men (P > 0.05). The insulin sensitivity was more decreased in postmenopausal than in pre-menopausal women. The insulin sensitivity index was -2.23 +/- 0.39 vs -1.73 +/- 0.13 (P < 0.05). The insulin resistance is associated with a clustering of risk factors of cardiovascular disease, more cluste-ring, more resistant.

Hyper-Rayleigh and hyper-Raman scattering background of liquid water in two-photon excited fluorescence detection

The detection of two-photon excited fluorescence is practically free from background caused by linear scattering because two-photon excited fluorescence occurs at a much shorter wavelength region than the excitation light. This property can be used to achieve ultrasensitive fluorescence detection. However, similar to linear scattering in the detection of one-photon excited fluorescence, the question arises whether background caused by non-linear scattering may limit the detection sensitivity of two-photon excited fluorescence. In this work, quantitative comparisons between two-photon induced scattering of liquid water and two-photon excited dye fluorescence in a standard epifluorescence geometry show that the relative scattering background is typically reduced by orders of magnitude in two-photon excitation as compared to single-photon excitation with confocal detection. Hyper-Rayleigh and hyper-Raman (3400 cm-1) cross sections of liquid water have been measured to be 8 x 10(-62) and 7 x 10(-63) cm4.s/photon, respectively, at 840 nm incident wavelength, with absolute values calibrated with respect to the known two-photon fluorescence excitation cross section of fluorescein.

[IR and UV-vis spectra of nitrogen-doped fullerene]

Nitrogen-doped fullerene derivative's IR and UV-vis spectra are reported. Some of the C60 IR silent modes are activated due to nitrogen atom reducing C60 molecular symmetry. UV-vis spectrum indicates nitrogen is donor.

[Efficacy of dihydroartemisinin in treatment of 37 malaria cases]

Dihydroartemisinin is an efficacious derivative of artemisinin which can be taken orally in treatment of malaria with less side reactions. Thirty-seven cases with malaria were treated with this drug in Beijing and in Ruili City, Yunnan Province. Out of them, 25 cases suffered from falciparum malaria with an average parasitemia of 73,218/microliter and 12 from vivax malaria with an average parasitemia of 4,950/microliter. The dosage was 60 mg daily or 2 mg/kg for paediatric patients for 7 successive days with the first dose doubled. All the patients were clinically cured after treatment. Fever subsided 22-72 hours after the beginning of treatment in falciparum malaria patients with an average fever clearance time of 36.24 +/- 15.30 hours and their parasite clearance time was 24-72 hours with an average parasite clearance time of 44.80 +/- 19.09 hours. One of them had recrudescence 19 days after the disappearance of parasites, hence the recrudescence rate of falciparum malaria was 4.8%. Five early cerebral cases in this series were completely cured after the treatment. All the 12 cases with vivax malaria were also clinically cured after treatment, but 1 case had relapse 35 days after treatment. This patient was completely cured with another course of dihydroartemisinin combined with primaquine. All patients tolerated well the oral administration of dihydroartemisinin and no significant side reactions were seen.

[Dobutamine technetium-99m-MIBI spect in evaluating the effects of coronary interventional management]

OBJECTIVE

To evaluate the effects of coronary interventional management by dobutamine 99mTc-MIBI single photon emission computed tomography (Dobu-ECT).

METHODS

Dobu-ECT was performed in pre- and post-interventional management of 32 patients. Dobutamine was administered intravenously at incremental rates from 5 to 40 micrograms x kg-1.min-1 at 3-minute intervals. At the highest infusion rate, 20 mCi 99mTc-MIBI was injected intravenously, and tomographic imaging was performed after one hour. Rest imagings were taken after 24 hours with a second dose of 99mTc-MIBI.

RESULTS

In 32 patients accepting interventional treatment, within 3-6 months follow-up, the results of Dobu-ECT showed a total effectiveness rate of treatment was 68.1%. 27 patients of whose Dobu-ECT showed significant reversible defects before procedure, the effectiveness rate was 77.8% (21/26), 6 still had reversible ischemia within the follow-up period, and restenoses of 5 patients were confirmed by angiography. We also compared the effect of percutaneous transluminal coronary angioplasty (PTCA) with intracoronary stenting using Dobu-ECT. The results showed that intracoronary stenting was more beneficial than PTCA (81.3% vs 43.8%, P < 0.05)

CONCLUSION

Dobu-ECT can be used to evaluate the effect of interventional management and detect restenosis after procedure.

[Mechanism of protective action of Phyllanthus urinaria L. against injuries of liver cells]

It has been found out that the carbon tetrachloride (CCl4)-induced increase of serum glutamic-pyruvic transaminase (ALT) and elevation of MDA in liver of mice are significantly lowered by Phyllanthus urinaria in vivo, and the coincubation of isolated rat hepatocytes with Phyllanthus urinaria in vitro significantly inhibits CCl4-induced decrease of mobility of membrane of liver cells and increase of intracellular free Ca2+ ([Ca2+]i) concentrations of liver cells. These results suggest that the anti-lipid peroxidation effect and protective action of membrane of Phyllanthus urinaria may be related to its protective action against CCl4-induced liver injuries.

Selenite suppression of cadmium-induced testicular apoptosis

The characteristic apoptotic ladder-like patterns of rat testicular DNA on agarose gel electrophoresis which results from treatment with CdCl2 are suppressed by the administration of Na2SeO3. The examination of testicular tissue using an ELISA programmed cell death detection procedure confirmed this selenite suppression of cadmium-induced apoptosis. The administration of the Na2SeO3 at either 0.5, 1, 2 h prior to or 0.5, 1, 2 h after the administration of the CdCl2 appear to be almost equally effective at suppressing the apoptotic response. These results are in accord with previous studies on the Na2SeO3 suppression of cadmium induced necrotic changes in tissues and suggest that Na2SeO3 interferes with both necrosis and apoptosis.

Measurement of group delay dispersion of high numerical aperture objective lenses using two-photon excited fluorescence

We determined the group-delay dispersion (GDD) of five microscope objectives by measuring the second-order autocorrelation at the focal points of the objectives with two-photon excited fluorescence as the power square sensor. We found that typical microscope lens systems introduce significant GDD (2000-6500 fs(2)). The third-order dispersion determined for these objectives limits the minimum obtainable pulse width at the focal point of an objective to 20-30 fs if not compensated. No significant chromatic aberration or higher-order dispersion effects were found for any of the optical components measured within the wavelength range of 700-780 nm and for pulse widths greater than 50-60 fs.

Binding domains for blockers and substrates on the dopamine transporter in rat striatal membranes studied by protection against N-ethylmaleimide-induced reduction of [3H]WIN 35,428 binding

Binding sites for 2 beta-carbomethoxy-3 beta-(4-fluorophenyl)[3H]tropane ([3H]WIN 35,428) on rat striatal membranes were alkylated with N-ethylmaleimide (NEM), and the protective potency was measured of the blockers cocaine, N[1-(2-benzo[b]thiophenyl) cyclohexyl]piperidine (BTCP), benztropine, WIN 35,428; and nomifensine, and of the substrates dopamine, norepinephrine, S(+)-amphetamine, tyramine, and metaraminol. In general, the protective potency was lower (at least 3 times) than the potency in inhibiting [3H]WIN 35,428 binding with the compounds present under the same experimental conditions used for the NEM-induced alkylation. However, the disparity was substantially greater for all substrates tested (10- to 93-fold) than for the blockers (2- to 6-fold), especially cocaine and BTCP (3-fold). [3H]WIN 35,428 binding was best described by a l-site model under the present conditions. The results are discussed in terms of models involving blocker-induced conformational changes and overlapping nonidentical binding domains for blockers and substrates.

[Analysis of 822 infants with limb reduction defect in China]

This work is aimed at the basic condition of infants with limb reduction defect (LRD) in China. 822 cases of LRD occurring among 1,243,284 live and stillbirths of 28 or more gestation weeks in China from Oct. 1986 to Sept. 1987 were analysed. The overall prevalence of LRD was 6.6 per 10,000 ranging from 14.4 per 10,000 to 3.6 per 10,000. No sex difference was observed. The prevalence of LRD in infants with low birthweight was significantly higher than that in infants with normal birthweight (P < 0.001). Also the prevalence of LRD in rural area was higher than that in urban area (P < 0.001). Four-limb involvement was most common. The cases with only upper limb involvement (278/451, 61.6%) were significantly more prevalent than those with only lower limb involvement (173/451, 38.4%, P < 0.001), but no difference was found between the left LRD and right LRD (P > 0.05), nor was a significant difference noted between single LRD and multiple LRD. 75.8% of the infants with LRD had defects in other systems.

A comparative study of intravenous accelerated streptokinase dose regimen with conventional dose regimen for coronary thrombolysis

The aim of this study is to test the patency rate and safety of the accelerated streptokinase dose regimen for coronary thrombolysis compared with the conventional one. One hundred and four patients entering three hospitals up to 12 hours after the onset of definite acute myocardial infarction were randomizely treated with intravenous accelerated streptokinase dose regimen (1.5 million units/30 min) (group A, 47 cases) and conventional dose regimen (1.5 million units/60 min) (group B, 57 casese). The reperfusion rate of infarct-related arteries determined by clinical evidence of reperfusion was 76.6% (36/47) in group A VS 61.4% (35/57) in group B. There was significant difference in reperfusion rates among patients within 6 hours after the onset of chest pain: 87.9% (29/33) in group A VS 67.4 (29/43) in group B (P < 0.05). The incidence of mild bleeding, allergic reaction, hypotension was 12.8% (6/47), 4.3% (2/47), 12.8 (6/47) respectively in group A vs 21.1 (12/57), 3.5 (2/57), 17.5% (10/57) respectively in group B. Compared to conventional dose regimen, intravenous accelerated streptokinase dose regimen for coronary thrombolysis seems to improve reperfusion rate markedly without increasing adverse events such as bleeding, allergic reaction and hypotension. It suggests that accelerated streptokinase therapy deserves more extensive investigation.

Binding domains for blockers and substrates on the cloned human dopamine transporter studied by protection against N-ethylmaleimide-induced reduction of 2 beta-carbomethoxy-3 beta-(4-fluorophenyl)[3H]tropane ([3H]WIN 35,428) binding

Binding sites for 2 beta-carbomethoxy-3 beta-(4-fluorophenyl)[3H]tropane ([3H]WIN 35,428) on the human dopamine transporter expressed in C6 glioma cells were alkylated with N-ethylmaleimide (NEM), and the protective potency of the blockers cocaine, N[1-(2-benzo[b]thiophenyl) cyclohexyl]piperidine (BTCP), and benztropine, and of the substrates dopamine, d-amphetamine, and norepinephrine was measured. In general, the protective potency was lower (at least 4-5 times) than the potency in inhibiting [3H]WIN 35,428 binding with the compounds present under the same experimental conditions used for the NEM alkylation. However, the disparity was substantially greater for all substrates tested (23- to 44-fold) than for the blockers (4- to 11-fold), especially cocaine (5-fold) and BTCP (4-fold). Benztropine took an intermediate place (11-fold) between cocaine (5-fold) and BTCP (4-fold), on the one hand, and dopamine (23-fold), on the other hand. [3H]WIN 35,428 binding was best described by a one-site model under the present conditions. The results are discussed in terms of models involving blocker-induced conformational changes and overlapping nonidentical binding domains for blockers and substrates.

[Transfer of thymidine kinase gene of herpes simplex virus mediated by retrovirus vector into ovarian cancer cells]

OBJECTIVE

To search for the application of the retrovirus vector (RV)/herpes simplex virus type I thymidine kinase gene (HSV-tk)/ganciclovior (GCV) gene therapeutic system in the treatment of ovarian cancer.

METHODS

Two kinds of vector-producing cells (VPC) which can produce retrovirus vectors constructed to contain neoR gene and two kinds of HSV-tk genes (marked as "HSV-tka" and "HSV-tkc) were employed to transfer those genes into ovarian cancer AO, 3AO cell lines. And the response of those anti-G418 clones to GCV therapy was observed.

RESULTS

In the transduction to AO cells, the vector titer of the VPC/HSV-tkc culture was 9.3 x 100,000 cfu/ml, and there were 263 anti-G418 clones in the 25 cm2 cell culture flask in which 1:1,000 diluted VPC/HSV-tkc culture was added, and 235 clones in a similar flask in which 1:10 diluted VPC/HSV-tka culture was added. Further more, all of the HSV-tkc positive clones exposed to 10 micrograms/ml GCV could be eliminated, and 96% of those clones died in 5 days after GCV was used.

CONCLUSIONS

The application of the RV/HSV-tk/GCV system is very promising in the gene therapy of ovarian cancer.

[The detection of the antibodies of human cytomegalovirus in the sera of patients with coronary heart disease]

To explore the relationship between human cytomegalovirus infection and atherosclerosis, we assayed the antibodies of human cytomegalovirus in the sera of 106 patients with coronary heart disease and 80 healthy people by indirect ELISA technique. The results showed that the positive rate of antibodies of HCMV IgG, HCMV IgM and HCMV IgA (95.3%, 12.3%, 13.2% respectively) is significantly higher than that in healthy people (85.0%, 2.5%, 3.8% respectively). Our findings indicated that HCMV infection is related to coronary heart disease. We consider that HCMV may be an etiological factor for human atherosclerosis. The periodical activation of latent HCMV may play a role in atherogenesis.

Fluoroquinolone resistance associated with specific gyrase mutations in clinical isolates of multidrug-resistant Mycobacterium tuberculosis

Fluoroquinolones are potent antibacterial agents being used clinically against multidrug-resistant tuberculosis. Treatment failure is thought to arise from acquisition of fluoroquinolone resistance by Mycobacterium tuberculosis. A collection of 13 resistant clinical isolates of M. tuberculosis was examined for ciprofloxacin sensitivity relative to controls exhibiting the same IS6110 DNA type. Specific alleles were associated with distinct levels of drug susceptibility for 11 isolates that contained nucleotide changes expected to alter the amino acid sequence of the A subunit of DNA gyrase. Five different gyrA (ciprofloxacin resistance) alleles were present among 7 isolates having the W DNA subtype. These isolates, which are representative of an outbreak strain, constitute a panel of organisms that can be used to evaluate contributions of gyrase and DNA topoisomerase IV to resistance.

Multiphoton fluorescence excitation: new spectral windows for biological nonlinear microscopy

Intrinsic, three-dimensionally resolved, microscopic imaging of dynamical structures and biochemical processes in living preparations has been realized by nonlinear laser scanning fluorescence microscopy. The search for useful two-photon and three-photon excitation spectra, motivated by the emergence of nonlinear microscopy as a powerful biophysical instrument, has now discovered a virtual artist's palette of chemical indicators, fluorescent markers, and native biological fluorophores, including NADH, flavins, and green fluorescent proteins, that are applicable to living biological preparations. More than 25 two-photon excitation spectra of ultraviolet and visible absorbing molecules reveal useful cross sections, some conveniently blue-shifted, for near-infrared absorption. Measurements of three-photon fluorophore excitation spectra now define alternative windows at relatively benign wavelengths to excite deeper ultraviolet fluorophores. The inherent optical sectioning capability of nonlinear excitation provides three-dimensional resolution for imaging and avoids out-of-focus background and photodamage. Here, the measured nonlinear excitation spectra and their photophysical characteristics that empower nonlinear laser microscopy for biological imaging are described.

Modeling of the pH dependence of the binding of WIN 35,428 to the dopamine transporter in rat striatal membranes: is the bioactive form positively charged or neutral?

Cocaine and its phenyltropane analogs, including 2beta-carbomethoxy-3beta-(4-fluorophenyl) tropane can exist in either the cationic or the neutral form, with the proportion of each form determined by the pKA and ambient pH. It is unknown which form is the active form for binding to the dopamine transporter. Our study examines the following models for the pH dependency of [3H]2beta-carbomethoxy-3beta-(4-fluorophenyl) tropane binding to the dopamine transporter in rat striatal membranes: 1) pH does not affect the binding affinity of the ligand for the dopamine transporter, and the observed binding is a function only of the concentration of the active form; and 2) pH affects the binding affinity of the ligand for the transporter, and changes in this affinity as well as in the concentration of the active form of the ligand in the medium contribute to the observed binding changes upon varying pH. For each model, predictions are formulated for the case that either the cation, neutral base, or both are the active form, and these predictions are compared with the experimental data obtained over a pH range of 6 to 9.5. Observations for 2beta-carbomethoxy-3beta-(4-fluorophenyl) tropane, which can be both in the cationic and neutral form, are compared with those for cocaine methiodide, which is permanently cationic, and benzocaine, which is permanently neutral. Consonant with all data is a simple model in which the cationic and neutral form have similar binding activity and binding changes as a function of pH are caused by changes at the level of the transporter rather than the ligand.

Translocation of dopamine and binding of WIN 35,428 measured under identical conditions in cells expressing the cloned human dopamine transporter

Translocation of [3H]dopamine and binding of [3H]WIN 35,428 were measured in intact C6 glioma cells expressing the cloned human dopamine transporter (hDAT) under identical conditions of assay buffer (phosphate-Krebs) and temperature (25 degrees C) with uptake at initial velocity and binding at equilibrium. In the intact cells, [3H]dopamine uptake was a one-component process; in contrast, [3H]WIN 35,428 binding included both a high-affinity component, inhibitable by micromolar concentrations of dopamine, and a low-affinity component only partially inhibited by millimolar concentrations of dopamine. Binding (high-affinity) over uptake Ki ratios were on the average 2.3 for the inhibitors WIN 35,428, cocaine, GBR 12909, and BTCP. The potency of dopamine in inhibiting its own translocation was close to that in inhibiting [3H]WIN 35,428 binding consonant with a more rapid reorientation step of the DAT in the C6-hDAT system than in rat striatal synaptosomes. The similarity in turnover values of the DAT estimated in the current experiments with the C6-hDAT system and in our previous study on rat striatal synaptosomes, performed under comparable conditions, suggest that all DAT's inserted into the C6 cell membrane are functionally active.

Effects of growth factors and interleukin-1 alpha on proteoglycan and type II collagen turnover in bovine nasal and articular chondrocyte pellet cultures

The aim of this study was to investigate the effects of insulin-like growth factor-I, transforming growth factor-beta (TGF-beta), and interluekin-1 alpha (IL-1 alpha) on the deposition and degradation of a cartilage-like matrix in high-density pellet cultures of adult bovine chondrocytes. Proteoglycan was determined by toluidine blue staining and colorimetric assay. Type II collagen was determined by immunohistochemical staining and its unwinding in situ by a recently developed immunoassay. Bovine nasal chondrocytes cultured as pellets deposited a well-organized extracellular matrix of proteoglycan and type II collagen. Insulin-like growth factor-I (2-10 ng/ml) increased the synthesis and incorporation into the matrix of both these proteins. TGF-beta (2-10 ng/ml) also increased proteoglycan synthesis. However it inhibited proteoglycan deposition, presumably through increased degradation of the molecule, as shown by increased release of aggrecan fragments into the tissue culture medium. TGF-beta had no effect on type II collagen deposition. In pellet cultures of bovine nasal or articular chondrocytes, 20 ng/ml IL-1 alpha induced a significant degradation of both proteoglycan and type II collagen. The effect on collagen clearly involved proteolytic cleavage of its triple helix because there was an increase in the proportion of unwound type II collagen in the matrix, as well as a loss of total type II collagen. In explant cultures of intact bovine articular cartilage, incubation with 50 ng/ml IL-1 alpha stimulated significant degradation of the proteoglycan but no degradation of the type II collagen. These results demonstrate that although the articular chondrocytes are capable of degrading type II collagen when isolated, they do not do so in situ, presumably because of some inherent property of the mature extracellular matrix. This study demonstrates the utility of pellet cultures when investigating chondrocyte-mediated turnover of cartilage matrix and its modulation by cytokines and growth factors.

Crystalline Ropes of Metallic Carbon Nanotubes

Fullerene single-wall nanotubes (SWNTs) were produced in yields of more than 70 percent by condensation of a laser-vaporized carbon-nickel-cobalt mixture at 1200degreesC. X-ray diffraction and electron microscopy showed that these SWNTs are nearly uniform in diameter and that they self-organize into "ropes," which consist of 100 to 500 SWNTs in a two-dimensional triangular lattice with a lattice constant of 17 angstroms. The x-ray form factor is consistent with that of uniformly charged cylinders 13.8 +/- 0.2 angstroms in diameter. The ropes were metallic, with a single-rope resistivity of <10(-4) ohm-centimeters at 300 kelvin. The uniformity of SWNT diameter is attributed to the efficient annealing of an initial fullerene tubelet kept open by a few metal atoms; the optimum diameter is determined by competition between the strain energy of curvature of the graphene sheet and the dangling-bond energy of the open edge, where growth occurs. These factors strongly favor the metallic (10,10) tube with C5v symmetry and an open edge stabilized by triple bonds.

Fluoroquinolone action in mycobacteria: similarity with effects in Escherichia coli and detection by cell lysate viscosity

Fluoroquinolones are potent antibacterial agents that are being used as therapeutic agents for the treatment of multidrug-resistant tuberculosis. To better understand fluoroquinolone action in mycobacteria, the effects of ciprofloxacin were examined. DNA synthesis was inhibited rapidly in Mycobacterium smegmatis, DNA cleavage was readily observed by an empirical assay of cell lysate viscosity, and cell growth was blocked. These data are explained by the formation of gyrase-DNA-ciprofloxacin complexes that block replication fork movement. The bactericidal action of ciprofloxacin against M. smegmatis, Mycobacterium bovis BCG, and Escherichia coli occurred more slowly in cells with longer doubling times. The bactericidal effect against M. bovis BCG was partially blocked by pretreatment with chloramphenicol, an inhibitor of protein synthesis, and by very high concentrations of ciprofloxacin itself. Similar responses occur when E. coli is treated with ciprofloxacin. These similarities between E. coli and mycobacteria indicate that results from extensive fluoroquinolone studies with E. coli can be applied to mycobacteria. A simple viscometric assay of DNA cleavage is described. The assay is expected to be useful for screening new fluoroquinolone derivatives for increased effectiveness against clinically important bacteria.

Ongoing mutation in MALT lymphoma immunoglobulin gene suggests that antigen stimulation plays a role in the clonal expansion

Indirect antigenic stimulation by H. pylori-specific T cells is implicated in the development of low-grade gastric lymphoma of mucosa-associated lymphoid tissue (MALT), however, the role of direct antigen stimulation is unknown. To study the role of direct antigen stimulation in MALT lymphomagenesis and its relationship with the pathogenesis of distinct pathological lesions, which represent different stages of the tumour progression, we cloned and sequenced the rearranged immunoglobulin (Ig) heavy chain gene in three low-grade (two from the lung, one from the stomach) and one high-grade (from the stomach) cases. In the low-grade gastric case, we studied the Ig sequence in primary as well as its disseminated and recurrent tumours. In the high-grade gastric case, we analysed the Ig sequence in tumour cell populations microdissected from the residual diffuse low-grade lesions, diffuse high-grade areas from follicles colonized by high-grade blasts. Compared with the published germline sequences, the heavy chain variable (VH) genes of three MALT lymphomas, in which the putative germline was identified, contained frequent somatic mutations, showing a much higher ratio of replacement/silent mutations in the complementarity determining regions (CDRs) than the framework regions (FRs). Ongoing mutation as indicated by intraclonal variation of the Ig sequence clearly existed in low-grade tumour including its dissemination and recurrence, but was not evident in high-grade tumour cell populations including those microdissected from independent colonized follicles. In addition, the germlines of VH genes used by the three MALT lymphomas are frequently found in autoreactive antibodies. Our results suggest that MALT lymphoma derives from postgerminal centre memory B cells, possibly autoreactive B cell clones, and that direct antigen stimulation may play an important role in the clonal expansion of low-grade MALT lymphoma.

Inhibitory effect of tetrahydropalmatine on calcium current in isolated cardiomyocyte of guinea pig

AIM

To study the effect of tetrahydropalmatine (THP) on calcium channels in ventricular single cells of guinea pig heart.

METHODS

Patch-clamp technique (whole cell recording) was used to observe calcium current in ventricular myocytes.

RESULTS

THP decreased ICa in ventricular myocytes with a dose and frequency-dependent manner. THP (0.1, 1, and 10 mumol.L-1) decreased ICa from 1.15 +/- 0.22, 0.91 +/- 0.18, and 1.60 +/- 0.42 nA (control) to 0.9 +/- 0.21 (P < 0.01), 0.56 +/- 0.21 (P < 0.01), and 0.83 +/- 0.21 nA (P < 0.05), respectively, number of cells is five in each group (n = 5), and the rates of the depression of ICa were 22%, 38%, and 48%, respectively. The effect was easily reduced by washing the cell with the Tyrode's solution. The current-voltage relation curve showed that the potential producing peak value of ICa was 0 mV at which THP had the most markedly inhibited action on ICa. When the stimulating frequency was changed, ICa varied in a frequency-dependent manner 5 min after THP was given, and the inhibition of THP was stronger at 2 Hz than that at 0.1 Hz.

CONCLUSION

THP possessed a Ca2+ channel blocking effect.

[Kindling of rat epilepsy by intracerebroventricular injection of norfloxacin and ultrastructural changes of brain]

AIM

To study the toxic effects of norfloxacin (Nor) on EEG and ultrastructure of the brain.

METHODS

EEG was recorded in the sensorimotor area of rat cortex after Nor 150 and 300 micrograms.kg-1 were injected into the right ventricle of the brain.

RESULTS

Spike waves occurred, first at the ipsilateral side and then bilaterally. The seizure spike appeared at 168 +/- 129, 51 +/- 35 s, and 276 +/- 138, 118 +/- 65 s in the right and left cerebral cortices in 150 and 300 micrograms.kg-1 groups, respectively. The wave forms were variable, the wave amplitude and frequency increased gradually, accompanied with limb twitching. Neuron degeneration was seen in both cerebral hemispheres, hippocampus, and cerebellum 120 min after the i.c.v. of Nor 300 micrograms.kg-1: myeloid degeneration of Golgi complex, rough endoplasmic reticulum, and neuropils; swelling of cytoplasm; dissolution of nuclears and chromatin; necrosis of gliocytes and the appearance of changes in both the light and dark neurons, especially the dark ones.

CONCLUSION

Rat brain was widely damaged after the kindling by Nor.

[Epidemiology of gastroschisis in China]

OBJECTIVE

To study the clinical and epidemiologic characteristics of perinates with gastroschisis (GA) in China.

METHODS

The birth defects monitoring program was undertaken in 945 hospitals from 29 provinces, cities and autonomous regions of China. Data about perinates including intrauterine death and stillbirth from 28 weeks of gestation to a period of 7 days after birth was collected through the medical records between October 1986 and September 1987.

RESULTS

A total of 194 cases with GA was found in 1243284 perinates monitored. The incidence of GA in China varied from 0.4 to 3.4 with a mean of 1.6 per 10,000. The highest prevalence was in Shandong province (3.4/10,000) which was significantly higher than the average (P < 0.01). The prevalence of GA perinates with low birth weight was higher than that with normal birth weight (1.6 vs 0.6 per 10,000, P < 0.01), as well as that in the rural area higher than in the urban area (2.5 vs 1.1 per 10,000, P < 0.01). 70.6% of the cases with GA were accompanied with other major defects. The overall perinatal mortality rate (PMR) of GA was 91.8%. PMR of GA with other birth defects (95.6%) was significantly higher than that of GA only (82.5%, P < 0.01). Only 15% of GA were diagnosed before birth.

CONCLUSIONS

GA was a serious malformation. Cases with GA had high PMR and low detection rates in prenatal diagnosis, and most often accompanied with multiple defects.

Single-epoch neuromagnetic signals during epileptiform activities in guinea pig longitudinal CA3 slices

Neuromagnetic fields with high signal-to-noise ratios can be measured above longitudinal CA3 slices of the guinea pig during single epochs of interictal- and ictal-like synchronized population activities. Technical refinements enabled us to reduce the number of epochs for clear responses from over 5000 needed in an earlier study to single epochs. Simultaneous recording of field potentials revealed that neuromagnetic fields reflect intracellular currents in the pyramidal cells. Intracellular currents could be estimated from the external magnetic fields during paroxysmal depolarization shifts, multiple bursts, and slowly varying potential shifts lasting several seconds.

Long-term follow-up of minimal residual disease in childhood acute lymphoblastic leukemia patients by polymerase chain reaction analysis of multiple clone-specific or malignancy-specific gene markers

Two types of markers, namely the clone-specific markers including T-cell receptor (TCR) gamma, TCR delta, and Ig heavy-chain (IgH) gene rearrangements, and malignancy-specific fusion gene mRNA such as SIL-TAL-1, BCR-ABL, and HRX-partner genes, were investigated by molecular biology techniques in 65 Chinese patients with acute lymphoblastic leukemia (ALL). In combination, these markers were informative among 96% of patients. Minimal residual disease (MRD) was followed up in 23 of these patients with available materials over a period varying from 8 to 54 months with at least one leukemia-specific probe. In most children, MRD was decreased continuously to an ultimately undetectable level within 6 to 12 months after remission induction therapy. One patient exhibited low-level residual leukemic cells for 4 years before the MRD turned negative. Another patient remained in complete remission for 45 months, although a positive signal was detected at 34 months using TCR delta probe, but was negative with a TCR gamma marker which was positive at presentation. In three patients who relapsed, MRD either persisted through the clinical course or became positive and eventually increased 3-11 months before clinical relapse. These data suggested that the combined use of multiple gene markers is a valuable tool for the PCR-based MRD detection, since it can cover most ALL patients. Furthermore, long-term follow-up of MRD is helpful for determining the dosage as well as the period of maintenance chemotherapy and for predicting impending relapse.

[An estimate of recurrence risk for neural tube defects in China]

A retrospective survey was made for estimating the recurrence risk of neural tube defects (NTD) in 233 hospitals of China during the period from July 1990 to June 1993. A total of 2159 women who born a baby with NTD in this pregnancy were investigated. Among them, 674 had one or more previous births (total in 889 births) before this pregnancy. Of the 889 children, 61 had NTD. Thus the overall estimate recurrence risk of NTD is 6.86%. The estimate recurrence risk of NTD is correlated with the prevalence. The estimate recurrence risks are 3.70%, 4.50% and 8.32% in the low-, average and high-prevalence areas respectively. There is a high recurrence risk for the same defect (anencephaly of spina bifida or encephalocele) of the index case.

[Study of heterogeneity in DNA ploidy and its clinical-pathological significance in esophageal squamous cell carcinoma]

In order to investigate the intratumoral DNA ploid heterogeneity in esophageal squamous cell carcinoma and its significance, nuclear DNA ploidy of 80 cases of squamous cell carcinoma of the esophagus were determined for multiple samples obtained from the same tumor, using a flow cytometry (FCM) technique. The results showed that: (1) DNA indeces ranged from 7.7-1.74, and the incidence of DNA aneuploidy was 88.8% (71/80) in this series; (2) of 80 cases, (47.5% 38 cases) showed intratumoral heterogeneity in DNA ploidy (3) the heterogeneity in DNA ploidy was related to the extent of wall penetration by tumor, the incidnce of lymph node metastasis and patient's prognosis, not to histological grades and size of tumor. The results from this study indicated that DNA ploidy heterogeneity may be a exact indicator in reflecting the biological characteristics of tumor and patient's prognosis than DNA aneuploidy from single site sampling.

Quantitative 1H and 31P MRS of PCA extracts of postmortem Alzheimer's disease brain

Several previous studies have shown metabolic abnormalities in perchloric acid extracts of postmortem Alzheimer's disease (AD) brain by both proton (1H) and phosphorus-31 (31P) magnetic resonance spectroscopy (MRS). In all of these studies the results were expressed in relative terms, in units of mol percent. The results of this study, expressed in the absolute units of mumol/g wet weight, verify the previous 1H and 31P MRS studies. Absolute increases were found for myo-inositol, aspartate, L-glutamate, alanine, phosphocholine, and the phosphodiesters,. Absolute decreases were found for phosphoethanolamine and N-acetyl-l-aspartate. Many of these changes also were observed in non-AD dementia brain extracts, but changes in myo-inositol, inositol-l-phosphate, aspartate, and L-glutamate appeared to be more specific for AD in extracts of many brain areas. These results suggest that compounds related to membrane degradation and excitatory neuro-transmission increase in Alzheimer's disease while compounds related to neuronal integrity and inhibitory neurotransmission are decreased.

Cadmium mobilization by nitrogen donor chelating agents

The relative abilities of a series of acyclic polyamine chelating agents containing only nitrogen donors (N-donors) to induce the urinary excretion of cadmium has been examined in the rat. The compounds examined include triethylenetetramine dihydrochloride (TRIEN), tris(2-aminoethyl)amine trihydrochloride (TREN), tetraethylenepentamine pentahydrochloride (TETRAEN), and pentaethylenehexamine hexahydrochloride (PENTAEN). Sodium N-methyl-D-glucamine-N-carbodithioate (NaG) was used as a positive control compound. The polyamines induced a significant increase in the urinary excretion of cadmium in rats that had been loaded with cadmium at least 4 d prior to the polyamine treatments. A comparison of these with similar data on macrocylic nitrogen donor systems, which form much more stable complexes with cadmium but are also ineffective in enhancing the excretion of cadmium from such aged deposits, suggests that the factors responsible for the relative inefficiency of these compounds may involve either a difficulty in penetrating cellular membranes or a slow rate of reaction with biologically bound cadmium. The occurrence of oliguria and anuria following the administration of the several of the polyamines indicates that their use is accompanied by significant renal damage in cadmium-exposed rats.