Susceptibility of human cells to killing by the parvoviruses H-1 and minute virus of mice correlates with viral transcription

Human fibroblasts and epithelial cells differing in their susceptibility to killing by the autonomous parvoviruses H-1 and minute virus of mice were compared for their capacity to express viral mRNAs and proteins. The transition from a parvovirus-resistant to a parvovirus-sensitive phenotype correlated with a proportional increase in the production of the three major viral transcripts and of structural and nonstructural proteins. In contrast, cell sensitization to parvovirus could not be correlated with detectable changes in virus uptake, intracellular localization of gene products, stability of viral mRNAs, or phosphorylation of viral nonstructural polypeptides. Moreover, the H-1 virus-sensitive keratinocyte line studied did not sustain a greater level of viral DNA amplification than its resistant derivative. Therefore, the differential susceptibility of the human cells tested to parvovirus infection appears to be mainly controlled at the level of transcription of the viral genome. Parvoviral gene expression could not be elevated by increasing the input multiplicity of infection in either of the cell systems analyzed. Together, these data suggest that a cellular factor(s) regulating parvoviral transcription may be modulated by oncogenic transformation or by differentiation, as both features have been shown to affect cell susceptibility to parvoviruses.

Aneurysmal bone cyst of the mandible--a case report

Aneurysmal bone cysts originating in the craniofacial region have seldom been reported in Taiwan. A case of aneurysmal bone cyst arising in the right mandible of a 15-year-old Chinese boy was presented with both the roentgenographic and microscopic findings. In view of the high recurrent rate and the large destructive mandibular lesion, segmental resection with immediate bone grafting for reconstruction and a conscientious follow up regimen was employed. The etiology and pathogenesis of this interesting lesion remained unclear but several theories were reviewed and the differential diagnosis of this lesion was also discussed. Furthermore, immunoperoxidase staining for Factor VIII related antigen was performed to help differentiate between the aneurysmal bone cyst and a central hemangioma and then to elucidate the pathogenesis of the former.

Impaired recovery and mutagenic SOS-like responses in ataxia telangiectasia cells

Radiosensitive fibroblasts from patients with ataxia telangiectasia (AT) were studied for their proficiency in two putative eukaryotic SOS-like responses, namely the enhanced reactivation (ER) and enhanced mutagenesis of damaged viruses infecting pre-irradiated versus mock-treated cells. A previous report indicated that, unlike normal human cells, a line of AT fibroblasts (AT5BIVA) could not be induced to express ER of damaged parvovirus H-1, a single-stranded DNA virus, by UV- or X-irradiation. In the present study, AT5BIVA fibroblasts were also distinguished from normal cells by the inability of the former to achieve enhanced mutagenesis of damaged H-1 virus upon cell UV-irradiation. In contrast, dose-response and time-course experiments revealed normal levels of ER of Herpes simplex virus 1, a double-stranded DNA virus, in X- or UV-irradiated AT5BIVA cells. Taken together, these data point to a possible deficiency of AT cells in a conditioned mutagenic process that contributes to a greater extent to the recovery of damaged single-stranded than double-stranded DNA. Such a defect may concern the replication of damaged DNA or the generation of signals promoting the latter process and may be related to the lack of radiation-induced delay that is typical of AT cell DNA synthesis.

[Clinical value of radionuclide whole body bone imaging in the diagnosis of skeletal metastasis]

Of 628 patients with extra-osseous malignancies diagnosed by surgery and/or pathology, 207 (33.0%) were identified as having skeletal metastasis by bone imaging. There was statistical significant difference in the incidence of metastasis in in different malignancies (P less than 0.02). The metastatic rates of nasopharyngeal, lung, prostate and breast cancers were higher than gastrointestinal, kidney, and other malignancies. There was significant differences in the different sites of skeletal metastasis (P less than 0.01). They were thorax, spine, pelvis, limbs and skull in order of incidence. Solitary metastatic rate was 15.9%. Biopsy is advised for patients suspected to have metastatic disease but with only one single "hot spot" in skeletal imaging, particularly in the rib.

[Power spectral analysis of heart rate in qi deficiency and both qi and yin deficiency in patients with coronary heart disease]

Qi deficiency (QD) and both Qi and Yin deficiency (QYD) are most common in TCM classification of CHD patients with insufficiency syndrome. The authors used the power spectrum of spontaneous heart rate fluctuation (PSHF) to analyze the function of cardiac regulation in 30 QD patients and 27 QYD patients with CHD and compare with the control group of 30 cases for discussing the association between different TCM syndrome patterns and the function of cardiac nerve regulation. The main results were as follows: (1) Low-frequency areas of PSHF in QYD (34.15 +/- 11.60%) were significantly higher than those in QD group (26.24 +/- 11.57%) and the control group (27.80 +/- 11.65%). The L/H ratio in QYD (1.78 +/- 0.96) was significantly higher than those in QD (0.91 +/- 0.64) and the control group (0.98 +/- 0.58). The changes of PSHF in QYD could have some relations with the increasing of the activity of sympathetic nervous system. (2) The change in body posture was used as a load test to study cardiovascular regulation in different TCM patterns of insufficiency syndrome with CHD. In control group the L/H ratio increased with the change of body posture from 0.98 +/- 0.58 to 4.29 +/- 0.89 (P less than 0.001), while in QD group and QYD group increased from 0.91 +/- 0.64 to 1.67 +/- 0.83 (P less than 0.05) and 1.78 +/- 0.96 to 1.85 +/- 0.87 (P greater than 0.2) respectively. The results suggested that cardiovascular baroreceptor reflex was decreased in CHD patients, and QYD group was inferior to DQ group.

Sensitization of human keratinocytes to killing by parvovirus H-1 takes place during their malignant transformation but does not require them to be tumorigenic

To investigate the antineoplastic activity of parvoviruses, proliferating normal human epidermal cells and a series of established keratinocyte cell lines derived from squamous cell carcinomas or transformed in vitro, were compared for the outcome of H-1 virus infection. All established keratinocyte cell lines were more sensitive to killing by H-1 virus than normal epidermal cells, although to varying extents. Using a step-wise procedure for malignant transformation in vitro, we found that sensitization of transformed epidermal cells to H-1 virus can be dissociated from the acquisition of a tumorigenic phenotype. Thus, spontaneously- or SV40-immortalized human keratinocytes were moderately and highly sensitive to H-1 virus, respectively, and could be made tumorigenic by Harvey-ras oncogene transfection without a major change in their susceptibility to the virus. The capacity of human keratinocytes for replicating and expressing H-1 virus DNA appears to be a revealer of cellular alterations that take place in at least some pathways to malignant transformation but that may be insufficient to confer a tumorigenic potential.

[Mechanism of cell damage by hematoporphyrin derivative (HPD) plus light. III. Effect of HPD plus light on lysosomes of liver and hepatoma cell]

The effects of HPD plus light on lysosome membrane and release of hydrolysis enzymes from lysosomes of normal rat liver and hepatoma cells were investigated. HPD was bound to lysosome either in vitro or in vivo. Lysosomes bound HPD plus light increased lipid peroxidation of unsaturated fatty acid of lysosome membrane and enhanced the activity of DNase, RNase, cathepsin and acid phosphatase. These effects were related to HPD concentration and exposure time but it was unchanged in the control. It was concluded that the enhancement of hydrolysis enzymes from lysosomes was due to the lysosome membrane damage under the action of siglet oxygen produced by HPD bound lysosomes following light activation.

Identification of a transformation-sensitive nuclear protein from normal human fibroblasts that specifically interacts with minute virus of mice DNA and correlates with cell resistance to the parvovirus

Normal human fibroblasts (MRC-5, KMS-6) were compared to transformed derivatives induced by SV40 (MRC-5V1) or gamma rays (KMST-6) for the expression of nuclear proteins that interact with the genome of minute virus of mice (MVMp), using the southwestern blot technique. A protein of 100-104 kDa apparent molecular weight was found to form a specific complex with MVMp DNA and to have an especially high affinity for the 3' terminal portion of the viral genome. This protein (p102) was differentially expressed by normal and transformed cells, i.e., its availability or DNA binding activity (or both) was much reduced in the transformants. A high level of p102 cosegregated with resistance to MVMp in cell hybrids between normal human and transformed mouse fibroblasts. Taken altogether these data suggest that the p102 protein may be a candidate for a transformation-sensitive cellular marker and for a negative regulator of parvovirus replication.

Transforming genes in duck hepatic carcinoma--mht(raf) and Ha-ras

The transfection of NIH 3T3 cells was performed with DNAs from 2 duck primary hepatic carcinomas (DHC 40K, 9K) and 1 tumor-adjacent liver tissue (TAL, 9N). Transfectants were found from 40K, 9K and 9N DNAs. The secondary transfectants were obtained after transfection of RAT-1 cells with DNAs from primary transfectants. After hybridization with Ha-ras, Ki-ras, N-ras and mht oncogenes, it was found that duck mht (5.2 and 3.2 kb EcoRI fragments) and duck Ha-ras (3.4 kb EcoRI fragments) were present in all these transformants. This is the first report on transforming genes in duck primary hepatic cancer as well as tumor-adjacent liver tissue.

[Mechanism of cell damage by hematoporphyrin derivative (HPD) plus light. II. Effect of HPD plus light on respiration and oxidative phosphorylation in hepatoma cells and normal liver mitochondria]

The effects of HPD plus light on energy metabolism and membrane structure of hepatoma cell and normal liver mitochondria were investigated. HPD was bound to mitochondria either in vitro or in vivo. Mitochondria bound HPD plus light increased MDA level, decreased respiratory intensity and respiratory control, dissociated phosphorylation from oxidation and enhanced mitochondria swelling on age. These effects were related to HPD concentration and exposure time but it was unchanged in the control. These results showed that the loss of function of oxidation phosphorylation was due to the mitochondrial membrane system damage under the action of singlet oxygen produced by HPD bound mitochondria following light activation.

Deficient expression of enhanced reactivation of parvovirus H-1 in ataxia telangiectasia cells irradiated with X-rays or u.v. light

Cells of patients with ataxia telangiectasia (AT), an inherited disease characterized by a high propensity to cancer, are hypersensitive to ionizing radiation. We investigated whether the hyper-radiosensitivity of AT cells correlated with a defect in their constitutive and/or conditional ability to rescue a damaged exogenous virus. For that purpose, parvovirus H-1, a single-stranded DNA virus whose intranuclear replication mostly relies on host cell functions, was used as a probe. The survival of u.v.- or gamma-irradiated H-1 was measured in X-, u.v.- or mock-irradiated human cells of normal (NB-E) or AT (AT5BIVA) origin. gamma-Irradiated H-1 survived to similar extents in untreated normal and AT cell lines. Both X- and u.v.-irradiation induced normal cells to achieve an enhanced reactivation (ER) of gamma- or u.v.-damaged H-1. In contrast, neither dose-effect curves nor time course revealed significant levels of ER expression after X- or u.v.-irradiation in AT5BIVA cells. Our results suggest that the impairment of ER of damaged parvoviruses may constitute a marker of the AT cell phenotype and be related to the radiosensitivity of AT cells.

[Mechanism of cell damage by hematoporphyrin derivatives (HPD) plus light--I. Photooxidation of hepatoma cell membrane by HPD plus light]

Ascitic hepatoma cells of mice were incubated with three HPD. After the cell-bound HPD was treated by visible light, the product of membrane lipid peroxidation--malondialdehyde (MDA) was determined. The results showed that the MDA level increased with HPD concentration and exposure time, but it was unchanged in the control. Beta-carotene, a quencher of singlet oxygen, could inhibit the lipid photooxidation of the membrane of cell-bound HPD resulting in a decrease of MDA level which decreased with increase of beta-carotene concentration. Adding vitamin E in vitro and vivo, formation of the product of membrane lipid peroxidation of cell-bound HPD by light was inhibited and the MDA level decreased with the increase of vitamin E concentration. These results show that the singlet oxygen, produced by HPD bound cells following light activation, reacts directly with the polyunsaturated fatty acids on cell membrane to produce lipid peroxides leading to cellular damage.

Selective killing of simian virus 40-transformed human fibroblasts by parvovirus H-1

A normal strain of human foreskin fibroblasts, two SV40-transformed derivatives with finite and infinite life spans, and an established line of SV40-transformed newborn human kidney cells are compared for their susceptibility to infection with parvovirus H-1. H-1 inocula, which do not detectably alter the growth of normal cells, cause a progressive degeneration of all three SV40-transformed cultures. The resistance of normal cells is not a membrane phenomenon since they adsorb and take up H-1 as efficiently as the transformants. Moreover, the fraction of infected cells supporting the synthesis and nuclear migration of H-1 proteins is similar in normal and SV40-transformed cultures. On the other hand, the enhanced H-1 sensitivity of transformed cells correlates with a 5- to 30-fold increase in their accumulation of newly synthesized parvoviral DNA, as compared with normal cultures. This stimulation of H-1 DNA replication is most pronounced for the amplification of duplex replicative forms, although the conversion of parental single-stranded DNA to replicative forms is also enhanced to a smaller extent. In addition, SV40-transformed cells support productive H-1 infection and release a burst of infectious virus, whereas no H-1 production can be detected in the normal cell strain. The latter difference was confirmed for another series of 7 normal and 16 SV40-transformed strains of human skin fibroblasts. Altogether, these results indicate that intracellular limitations on H-1 DNA replication are associated with the abortive nature of the parvoviral life cycle in normal human fibroblasts and are overcome after SV40 transformation, resulting in the selective killing of the transformants. This observation raises the possibility that oncolysis might contribute to the oncosuppressive activity displayed by parvoviruses in vivo.

Purification and characterisation of a 12 K dalton peptide with an affinity for oriC containing DNA fragments from Escherichia coli K12 membrane fractions

A DNA binding protein capable of interacting specifically with oriC containing DNA was purified to near homogeneity from E. coli membrane fractions. It has a molecular weight of 12 KD in denaturing conditions. The specific binding to oriC DNA is more resistant to the presence of salt than the non specific binding. Neither the DNA binding activity nor the specificity for oriC DNA was destroyed by heating at 100 degrees C for 2 min.