Expression of mitochondrial genes and DNA-repair-related nuclear genes is altered in xeroderma pigmentosum fibroblasts

Differential hybridization was used to detect repair defects in xeroderma pigmentosum (XP) that are not amenable to current analyses. cDNA libraries were constructed from cytoplasmic RNA of normal and XP fibroblast strains (complementation groups A and D) and analyzed for differential gene expression. More than 40,000 lambda gt10 cDNA clones were differentially screened with in vitro transcripts made from cDNA in the pBluescript vector. Six differential clones were detected in the libraries of the XP group A and D strains which caused stronger or weaker signals when probed with transcripts from XP strains than with those from the normal strains. Two clones coded for mitochondrial genes: mitochondrial 16 S rRNA and ATPase 6L. Overexpression of mitochondrial genes in XP may indicate that functions of the ATP-generating system are impaired since such functions are intensified whenever they become insufficient, for example as a consequence of DNA damage. It is tempting to assume that abnormal mitochondria are one of the causes for the neurological malfunctions in XP. Furthermore, densitometric analysis of Northern blots revealed that mRNA of lactate dehydrogenase, chain M, was less abundant in four XP group A strains (extent of reduction: 70%) and in two XP group D strains (extent of reduction: 58%). Enzyme activity was also diminished. In addition, mRNA of the gene for glyceraldehyde-3-phosphate dehydrogenase was less expressed in the same XP group A and D fibroblast strains investigated (reduction in both complementation groups: 50%). Both glycolytic enzymes have nuclear functions apart from their role in sugar metabolism. Lactate dehydrogenase, chain M, is identical to a helix-destabilizing protein; it is closely associated with chromatin and unfolded DNA, suggesting a role in DNA synthesis and transcription. The 37-kDa subunit of glyceraldehyde-3-phosphate dehydrogenase is involved in transcription and was shown to be identical to uracil-DNA glycosylase, a base-excision repair enzyme. We presume that the nuclear functions of these glycolytic enzymes may be thwarted in the XP strains investigated and may account for malfunctions in XP, particularly for neurological disturbances.

Myocardial velocity gradients detected by Doppler imaging

Using a scanner whose colour Doppler mode has been adapted to display tissue motion (instead of blood flow), velocity gradients have been detected across the myocardium. A velocity gradient is a gradual spatial change in the value of velocity estimates. Velocity gradients have potential for assessing regional myocardial contractility. 28 M-mode scans were performed on nine normal volunteers at different locations in the left-ventricle posterior wall. In each case simultaneous Doppler M-mode and pulse-echo M-mode images were obtained. Doppler velocity gradient (DVG) was calculated from Doppler M-mode images and rate of change of wall thickness (RCWT) was calculated from pulse-echo M-mode images. In all Doppler M-mode images statistically significant velocity gradients were observed. In all but one scan, cyclically consistent peaks in DVG occur relative to the electrocardiogram waveform. 99% of systolic and 89% of early diastolic peaks in RCWT have a corresponding peak in DVG. Velocity gradients are consistent with wall thickness changes, suggesting that they have potential for assessment of myocardial contractility.

An AT-rich satellite DNA sequence, E180, in alfalfa (Medicago sativa)

A DNA fragment of approximately 750 bp was cloned from EcoRI-digested nuclear DNA of alfalfa (Medicago sativa). Southern blot and sequence analysis showed that the cloned DNA fragment represents a tetramer of a highly tandemly repeated DNA sequence of 185-188 bp (E180). The consensus sequence deduced from the four repeating units is 189 bp in length with an AT content of 67%. The copy number of the satellite DNA was estimated to be approximately 1.8 x 10(5) per genome and constitutes about 1% of the alfalfa genome. Sequence comparison revealed no identity to any repetitive DNA sequences that have been published to date. Digestion with HpaII and MspI indicated a high degree of methylation at the internal C of the restriction site CCGG within E180.

Optoelectronic implementation of a compression-attraction-sphere associative memory using an optical spatial pattern-encoding method

A compression-attraction-sphere associative-memory model is proposed. An optoelectronic implementation of its inner-product architecture using an optical spatial pattern-encoding method is demonstrated bycomputer simulations and preliminary experiments.

Structure and evolution of a highly repetitive DNA sequence from Brassica napus

A Hind III family of highly repetitive DNA sequences, canrep (canola repeat), was cloned from the nuclear DNA of canola (Brassica napus cv. Westar). The basic units of this family of repeats consists of 176 bp and are arranged in clusters of tandem direct repeats. Each canrep repeat is composed of three related subrepeats of ca. 60 bp. Each subrepeat contains two inverted repeats of about 23 bp and another unrelated sequence of about 12 bp. Based on the internal structure, a possible scheme for the evolution of canrep is proposed. At least two subfamilies of the canrep sequences are present in the genome, as revealed by sequence analyses. In situ hybridization showed that canrep sequences are mainly clustered at centromeric regions of chromosomes. Northern hybridizations indicate that there are no transcripts related to canrep in the total RNAs extracted from plant seedlings.

A priori evaluation of aqueous polarization effects through Monte Carlo QM-MM simulations

A Monte Carlo quantum mechanical-molecular mechanical (QM-MM) simulation method was used to determine the contributions of the solvent polarization effect to the total interaction energies between solute and solvent for amino acid side chains and nucleotide bases in aqueous solution. In the present AM1-TIP3P approach, the solute molecule is characterized by valence electrons and nucleus cores with Hartree-Fock theory incorporating explicit solvent effects into the total Hamiltonian, while the solvent is approximated by the three-point charge TIP3P model. The polarization energy contributes 10 to 20 percent of the total electrostatic energy in these systems. The performance of the hybrid AM1-TIP3P model was further validated by consideration of bimolecular complexes with water and by computation of the free energies of solvation of organic molecules using statistical perturbation theory. Excellent agreement with ab initio 6-31G(d) results and experimental solvation free energies was obtained.

Human recombinant IL-3 is a growth factor for normal B cells

IL-3 is a well known hemopoietic cell growth and differentiation factor. However, its functional role in normal B cell differentiation has not been established. We have investigated the effect of IL-3 on the growth and differentiation of human B cells. IL-3 enhanced the proliferation of Staphylococcus aureus Cowan 1 strain-stimulated B cells. The optimal time of IL-3 to stimulate B cell growth was on day 2 to day 3, suggesting that IL-3 was a B cell growth factor acting in the late stage. IL-3 synergized with IL-2 to enhance B cell proliferation and differentiation. Pretreatment of B cells with IL-3 for more than 3 days increased the expression of IL-2R on B cells. However, pretreatment of B cells with IL-2 did not alter the subsequent response to IL-3, suggesting that the synergy between IL-2 and IL-3 may be attributed to the up-regulation of IL-2 response by IL-3. In addition, pretreatment of B cells with IL-4 decreased subsequent response of B cells to IL-3 as well as IL-2, suggesting that IL-3- and IL-2-responding cells passed a similar way during the early stage of B cell activation. It appears that IL-3 and IL-6 mediate normal B cell differentiation via separate mechanisms. IL-3-induced B cell differentiation was mainly mediated by increasing cell growth, whereas IL-6 induced B cell differentiation without affecting proliferation.

Human recombinant IL-3 is a growth factor for normal B cells

IL-3 is a well known hemopoietic cell growth and differentiation factor. However, its functional role in normal B cell differentiation has not been established. We have investigated the effect of IL-3 on the growth and differentiation of human B cells. IL-3 enhanced the proliferation of Staphylococcus aureus Cowan 1 strain-stimulated B cells. The optimal time of IL-3 to stimulate B cell growth was on day 2 to day 3, suggesting that IL-3 was a B cell growth factor acting in the late stage. IL-3 synergized with IL-2 to enhance B cell proliferation and differentiation. Pretreatment of B cells with IL-3 for more than 3 days increased the expression of IL-2R on B cells. However, pretreatment of B cells with IL-2 did not alter the subsequent response to IL-3, suggesting that the synergy between IL-2 and IL-3 may be attributed to the up-regulation of IL-2 response by IL-3. In addition, pretreatment of B cells with IL-4 decreased subsequent response of B cells to IL-3 as well as IL-2, suggesting that IL-3- and IL-2-responding cells passed a similar way during the early stage of B cell activation. It appears that IL-3 and IL-6 mediate normal B cell differentiation via separate mechanisms. IL-3-induced B cell differentiation was mainly mediated by increasing cell growth, whereas IL-6 induced B cell differentiation without affecting proliferation.

[Preparation of compound membrane of traditional Chinese medicine for mouth ulcer]

The compound membrane of traditional Chinese medicine for mouth ulcer, which is made of drug-containing membrane and covering membrane, is a new type of preparation of traditional Chinese medicine. The comparison of different prescriptions and membrane materials in the preparation, adhesion and drug release of the membrane has shown that that PVA17-88-CMCNa (1:1) and PVA17-88 act best as the base of drug-containing membrane and covering membrane material respectively.

[An epidemiologic survey on a type E hepatitis (HE) outbreak]

This article deals with a HE outbreak, which occurred in Sulagong Village, Pan-jin Township, Yining County, Xinjiang. There was a total of 214 patients involved in the village, with an attack rate of 6.15 percent. Among the patients young people formed the majority. The attack rate between 20 to 24 years of age reached 17.9 percent. Attack rate of pregnant women between 18 to 35 years of age was significantly higher than that of the non-pregnant ones. The condition in pregnant patients was rather severe. Their case fatality rate was 5.88 percent and abortion rate was 17.64 percent. By epidemiological investigation, it was shown that the chief contributing cause of the HE outbreak was probably contaminated drinking water, and direct or indirect contact with the patients in the infectious stage was also a risk factor.

IL-4 blocks the up-regulation of IL-2 receptors induced by IL-2 in normal human B cells

A negative influence of IL-4 on the IL-2-induced B cell proliferation and differentiation has recently been reported. In this study, we have further investigated a role of IL-4 on human tonsillar B cell proliferation and IL-2R expression. IL-4 enhanced Staphylococcus aureus Cowan 1 strain (SAC)-induced B cell proliferation, reaching the peak on day 3. However, from day 4, IL-4 inhibited IL-2-induced proliferation. In the cross-linking study, IL-4 enhanced the density of 125I-IL-2-binding protein at low affinity binding condition (2 nM of 125I-IL-2) in SAC-activated B cells. However, IL-4 blocked the enhancement in the density of 125I-IL-2-binding proteins induced by IL-2, from day 3, in both high (50 pM of 125I-IL-2) and low affinity binding conditions, suggesting that IL-4 is able to block IL-2-induced IL-2R up-regulation. This was confirmed by a binding study: B cells that cultured for 3 days with SAC plus IL-2 expressed an average of 180 +/- 20 high affinity receptors/cell with a Kd of 12 pM and 5800 +/- 500 low affinity receptors/cell with a Kd of 980 pM. By coculturing with IL-4, high affinity receptors were almost undetectable and the expression of low affinity receptors was reduced by more than 80%. IL-4-mediated inhibition of IL-2-induced IL-2R expression does not seem to be due to the direct interaction between IL-4 and cell surface receptors, inasmuch as preincubation of cells with IL-4 for 60 min at 37 degrees C did not alter the binding of 125I-IL-2 to cells previously cultured for 3 days with SAC plus IL-2. These data suggest that IL-4 has a capacity to block the up-regulation of the high as well as low affinity IL-2R-induced by IL-2 in normal human B cells, and could provide a possible explanation for the decreased responsiveness of B cells to IL-2 in the presence of IL-4.

IL-4 blocks the up-regulation of IL-2 receptors induced by IL-2 in normal human B cells

A negative influence of IL-4 on the IL-2-induced B cell proliferation and differentiation has recently been reported. In this study, we have further investigated a role of IL-4 on human tonsillar B cell proliferation and IL-2R expression. IL-4 enhanced Staphylococcus aureus Cowan 1 strain (SAC)-induced B cell proliferation, reaching the peak on day 3. However, from day 4, IL-4 inhibited IL-2-induced proliferation. In the cross-linking study, IL-4 enhanced the density of 125I-IL-2-binding protein at low affinity binding condition (2 nM of 125I-IL-2) in SAC-activated B cells. However, IL-4 blocked the enhancement in the density of 125I-IL-2-binding proteins induced by IL-2, from day 3, in both high (50 pM of 125I-IL-2) and low affinity binding conditions, suggesting that IL-4 is able to block IL-2-induced IL-2R up-regulation. This was confirmed by a binding study: B cells that cultured for 3 days with SAC plus IL-2 expressed an average of 180 +/- 20 high affinity receptors/cell with a Kd of 12 pM and 5800 +/- 500 low affinity receptors/cell with a Kd of 980 pM. By coculturing with IL-4, high affinity receptors were almost undetectable and the expression of low affinity receptors was reduced by more than 80%. IL-4-mediated inhibition of IL-2-induced IL-2R expression does not seem to be due to the direct interaction between IL-4 and cell surface receptors, inasmuch as preincubation of cells with IL-4 for 60 min at 37 degrees C did not alter the binding of 125I-IL-2 to cells previously cultured for 3 days with SAC plus IL-2. These data suggest that IL-4 has a capacity to block the up-regulation of the high as well as low affinity IL-2R-induced by IL-2 in normal human B cells, and could provide a possible explanation for the decreased responsiveness of B cells to IL-2 in the presence of IL-4.

Recombinant interleukin (IL) 2-induced human B cell differentiation is mediated by autocrine IL6

The molecular mechanism of the interleukin (IL) 2-induced differentiation of human B cells has been investigated. The experimental results show that Staphylococcus aureus Cowan strain I (SAC) activation alone induces IL6 secretion from B cells. When B cells were activated by SAC, there was an increased transcription of the IL6 mRNA. It reached the peak level by 6 h and rapidly decreased to an undetectable level within 24 h. The IL6 concentration in the culture supernatants reached the peak at 24-48 h and decreased slightly in the following culture periods. Since IL 2 alone could induce IgG secretion, whether exogenous IL6 was added or not, and IL2 did not increase autocrine IL6 synthesis, it appears that IL2 induces the IL6 responsiveness of SAC-activated B cells to differentiate in the later stage of the culture. The addition of polyclonal anti-IL6 antibody inhibited IgG secretion. The antibody still efficiently blocked IgG secretion up to day 5, indicating an important role of autocrine IL6 in the IL2-driven B cell differentiation. However, the saturation dose of anti-IL6 antibody inhibited 50%-70% of IgG secretion, suggesting that IL2-induced B cell differentiation appears to be mediated by other factors besides IL6.