The spread of human lung cancer cells on collagens and its inhibition by type III collagen.

The cell spreading ability of human lung cancer cells on collagen substrata was examined in comparison with normal human tracheal epithelial cells. Plastic dishes or multiwells were coated with type I, III or IV collagen gel at a concentrate of 200 micrograms/cm2. Ninety per cent of the normal cells were round on all collagens. Adenocarcinoma RERF-LC-MS and VMRC-LCD cell lines and squamous cell carcinoma VMRC-LCP cell line, which metastasize weakly after intrasplenic transplantation in nude mice, spread relatively poorly. Adenocarcinoma, A549 and SK-LU-1 and squamous cell carcinoma Calu-1 cell lines, which were highly metastatic to liver, spread well. Adenocarcinoma ABC-1 cell line, which is moderately metastatic to liver in nude mice, spread moderately. On type III collagen, three adenocarcinoma cell lines (A549, ABC-1 and VMRC-LCD) gradually started to contract after initial spreading and became round at 24 h. These results suggest that there may be a correlation between the degree of malignancy of human lung cancer cells and their spreading ability on collagen substrata, and that the cell spreading ability may be regulated by type III collagen in some lung cancer cells.

Inactivation of herpes viruses by high hydrostatic pressure.

The effects of high hydrostatic pressure on herpes simplex virus type 1 (HSV-1) and human cytomegalovirus (HCMV) were examined. Pressure at more than 300 MPa for 10 min at 25 degrees C inactivated these virions and drastically inhibited their infection to cultured cells, and at greater than 400 MPa, reduced infective titers of HSV-1 and HCMV by more than 7 and 4 logs, respectively. Electron microscopic examination illustrated coincidentally that high pressure at 300 MPa damaged the virus envelope and prevented the virus particles from binding to the cells. The findings suggest that treatment at high hydrostatic pressure is promising as a means of inactivating HSV-1, HCMV and other enveloped viruses.

Behavior of axons, Schwann cells and perineurial cells in nerve regeneration within transplanted nerve grafts: effects of anti-laminin and anti-fibronectin antisera.

Wistar rats (close cloned strain) were used to investigate the effect of endogenous laminin and fibronectin on axons, Schwann cells and perineurial cells in the regenerating peripheral nervous system (PNS). Sciatic nerve grafts obtained from donor rats were frozen, thawed and treated with rabbit anti-rat laminin or anti-fibronectin antiserum. Control grafts were treated with normal rabbit serum alone. One cm long portions of the sciatic nerve of the recipient rats were replaced with grafts. At 15 days after transplantation the number of regenerated axons in the laminin- and fibronectin-depleted grafts was half of that in the control. The growing axons in the laminin-depleted grafts did not recognize the basal lamina scaffolds (BLS) remaining in the basal lamina tubes, while in the control and fibronectin-depleted grafts 90% or more of axons grew inside the BLS. Elongation of axons always preceded migration of Schwann cells with the latter subsequently adhering to and wrapping around the former. Perineurium-forming fibroblastic cells recognized the combination of axons and Schwann cells and formed perineurial fasciculi around them. These fibroblastic cells did not recognize empty BLS but responded to them only when fibronectin was depleted. Macrophages sometimes closely faced the naked axons which elongated outside the BLS. These results suggest that in the early stages of nerve regeneration endogenous laminin and fibronectin not only regulate the growth of regenerating nerve fibers, but also exert a positive influence on perineurial cells and macrophages, both of which play important roles in nerve tissue injury and repair.

Effects of high hydrostatic pressure on characteristics of pork slurries and inactivation of microorganisms associated with meat and meat products.

Pork slurries inoculated with various test microorganisms were prepared and subjected to high hydrostatic pressure at 1000 to 6000 atm for 10 min at 25 degrees C to examine for the pressure effects on characteristics of the slurries and the inactivation of the microorganisms associated with meat and meat products. Pressure treatment at higher than 3000 atm caused coagulation and discoloration of the pork slurries. Harder and more white coagulants were obtained by increasing the pressure. Pressure treatment at 3000 to 6000 atm killed all the microorganisms tested by more than 6-log colony-forming units (cfu)/g except Bacillus cereus spores. Gram-negative microorganisms were more labile to pressure than Gram-positive ones. Campylobacter jejuni, Pseudomonas aeruginosa, Salmonella typhimurium and Yersinia enterocolitica were inactivated at pressures higher than 3000 atm; Escherichia coli, Saccharomyces cerevisiae and Candida utilis at pressures higher than 4000 atm; Micrococcus luteus, Staphylococcus aureus and Streptococcus faecalis at 6000 atm. Only less than one-log cfu/g of B. cereus spores were inactivated at 6000 atm. Ultraviolet absorption spectra and acridine orange staining suggested that E. coli became permeable and leaked cytoplasmic RNA at lower pressure than S. aureus. From the present findings, the authors propose high hydrostatic pressure treatment as a promising means of preparing wholesome meat and meat products.

ADRF Trebitsch Scholarship. The microbial contamination of toothbrushes. A pilot study.

Ten individuals were each supplied with a new toothbrush of the same type and brand, together with identical tubes of fluoridated toothpaste. After a three-week period, during which subjects were asked to follow their usual oral hygiene practices, the toothbrushes were collected and assayed for microbial contamination using a range of selective growth media. The total microbial load per toothbrush was found to be 10(4) to 10(5) colony forming units. Staphylococci were found on all toothbrushes and streptococci on all but one. These two genera were also quantitatively dominant. Candida, corynebacteria, pseudomonads and coliforms were identified in 70, 60, 50 and 30 per cent of toothbrushes, respectively. However, mutans streptococci, lactobacilli and black-pigmented Gram-negative anaerobic rods were not detected on any of the toothbrushes. For each individual, information on variables such as toothbrush rinsing practices and post-brushing storage methods and environment was collected. No obvious relationship between such variables and microbial load was apparent but it is suggested that more extensive studies are needed, taking into account additional parameters such as age and degree of toothbrush wear and the use of pre-brushing mouthwashes.

Localised enamel hypoplasia of human deciduous canines: genotype or environment?

A discrete area of defective enamel formation that appears on the labial surface of the crowns of deciduous canine teeth has been described in both recent and prehistoric human populations, with reported frequencies varying from 1 to 45 per cent. Suggestions about the aetiology of this localized hypoplasia range from genotypic factors to environmental conditions and systemic effects. The major aims of this study were to describe the frequency of occurrence and pattern of expression of the lesion in Australian Aboriginal and Caucasian ethnic groups, and to clarify the role of genetic factors by examining a sample of twins. The study sample consisted of dental casts of 181 pairs of Australian Caucasian twins, 215 Aborigines and 122 Caucasian singletons, together with 253 extracted deciduous canines. Examination of dental casts and extracted teeth was undertaken under 2x magnification with emphasis being placed upon location and expression of the lesion. The defect was observed in 49 per cent of twins and 44 per cent of Aborigines, but only 36 per cent of singletons. The percentages of affected teeth in each group were: 18 per cent in twins, 17 per cent in Aborigines and 13 per cent in Caucasians. A significant proportion of the defects occurred on the mesial aspect of the labial surface, in the middle area incisocervically, with the majority in the lower jaw. A number of significant differences in frequency were observed between groups, sexes, arches and sides. The results confirm some of the findings of previous studies, but also suggest that none of environmental, genetic or systemic factors can be ruled out as being involved in aetiology of the defect. The higher incidence of the lesion occurring on the mesial aspect of the labial surface is suggestive of physical trauma. Also, the vulnerability of the prominent developing mandibular canine, with its thin or missing labial covering of bone, would be expected to lead to higher prevalence of the lesion in the lower jaw. Although not definitive, the results of concordance analyses in twins were suggestive of a possible genetic predisposition in the formation of the lesion. Further research with a greater clinical orientation and emphasis on determining specific aetiological factors within any given environment in different ethnic groups may provide better insight into the ambiguous aetiology of the hypoplastic enamel defect.

A literature review of dental erosion in children.

Dental erosion is increasingly recognized as a common condition in paediatric dentistry with complications of tooth sensitivity, altered aesthetics and loss of occlusal vertical dimension. The prevalence of erosion in children has been reported to range from 10% to over 80%. The primary dentition is thought to be more susceptible to erosion compared to the permanent dentition due to the thinner and less mineralized enamel. The aim of this paper was to critically review dental erosion in children with regards to its prevalence, aetiology, diagnosis and prevention. The associations between erosion and other common conditions in children such as caries and enamel hypoplasia are also discussed.

Arterial pressure and its variability in conscious rabbits at different ages.

Mean level and its variability of mean arterial pressure (MAP) were studied in 25 unanesthetized rabbits aged 6, 12, 18, 24 and 30 months. They were selected from the same large colony and bred with an ordinary rabbit food under a given environmental conditions. MAP in the aortic arch was continuously monitored with a catheter-transducer system for 3 hrs. Mean (M) and variance (V) of MAP for 3 hrs were not significantly altered with aging (p greater than 0.05, Kruskal-Wallis' multi-sample test). Intra-animal variations of the M and SD were small. Most of histograms of MAP for 3 hrs shows an exaggerated mode at any age. Distribution pattern of the histogram was not specific to age. These suggest that responsiveness of the baroreflex system should not be affected by aging from 6 to 30 months.

Studies on medicinal resources from livestock. II. Anti-allergic effects of pig bile. (2).

Anti-allergic activities of lyophilized pig bile [( PB]) were examined in mice with picryl chloride-induced contact dermatitis (PC-CD), an experimental model of delayed-type hypersensitivity (DTH; type-IV allergy). PC-CD was markedly inhibited by an oral administration of [PB] within 4 h after but not during 8 to 16 h after challenge with picryl chloride. Anti-inflammatory activities of [PB] were also examined in acetic acid-induced mouse increased vascular permeability, hypotonic-hyperthermic lysis of rat erythrocytes and carrageenin-induced rat hind paw edema. [PB] had no effect on these models. The present study suggests that [PB] inhibits PC-CD through its immuno-modulation in the inductive phase of DTH rather than by an anti-inflammatory action.

Antiviral activity of a bile pigment, biliverdin, against human herpesvirus 6 (HHV-6) in vitro.

Biliverdin (BV), a bile pigment, was examined for its antiviral activity against human herpesvirus-6 (HHV-6) in vitro. BV (10 micrograms/ml) markedly inhibited HHV-6 replication in MT-4 cells when the cells were treated during a virus adsorption period. Its antiviral effect was weakened when cells were treated after adsorption. Treatment of cells with BV (40 micrograms/ml) 3 hr after virus infection had no inhibitory effect on virus replication. Virus replication was also significantly inhibited by treatment of MT-4 cells with BV (10 micrograms/ml) before infection, while the virions were not inactivated by BV (20 micrograms/ml). Bilirubin and urobilin, metabolic derivatives of BV, showed slight inhibitory effects on virus replication in the cells. On the other hand, BV had no potent inhibitory activity in the replication of herpes simplex virus-1 or human cytomegalovirus. These observations suggest that BV could interact with MT-4 cells to inhibit an early stage of HHV-6 infection in a virus-specific manner.

Studies on medicinal resources from livestock. I. Anti-allergic effects of pig bile. (1).

Anti-allergic activities of animal biles and commercially available bile acids were evaluated in experimental allergic disease models. Pig bile exhibited marked preventive effects on the models of delayed-type hypersensitivity (type IV allergy), picryl chloride-induced contact dermatitis (PC-CD) and sheep red blood cells (SRBC)-induced footpad swelling in mice. Fel ursi (dried bear gallbladder) also had an inhibitory effect on PC-CD, whereas ox bile, chicken bile and bile acids had no effect on ether of the models.

In vitro anti-human immunodeficiency virus type 1 activity of biliverdin, a bile pigment.

Biliverdin (BV) is a bile pigment having anti-allergic properties. We examined the effect of BV on human immunodeficiency virus type 1 (HIV-1) in vitro. BV completely inhibited the cytopathic effect of HIV-1 in MT-4 cells at concentrations of 22.2 micrograms/ml or more. This inhibitory effect was also observed when BV was present during the adsorption period of HIV-1. However, BV was cytotoxic to MT-4 cells at concentrations above 800 micrograms/ml. At a concentration of 66.7 micrograms/ml, BV completely inhibited syncytia formation by HIV-infected and uninfected MOLT-4 cells. Moreover, after exposure of HIV-1 particles to BV for 2 h, the infectivity of the virus was reduced in a dose-dependent manner. It is speculated that the anti-HIV activity of BV is due to direct inactivation of virions and inhibition of virus binding to target cells.

Correlation between release of reactive oxygen intermediates and inhibition of Toxoplasma multiplication in mouse peritoneal and alveolar macrophages and kidney cells after in vitro incubation with Obioactin, lonomycin A, muramyl dipeptide, lipopolysaccharide or Toxoplasma lysate antigen.

The inhibition of Toxoplasma multiplication inside cells does not correlate with an enhanced release of oxygen intermediates except in the case of peritoneal macrophages treated with Obioactin. The inhibition observed in alveolar macrophages treated with Obioactin, in kidney cells treated with Obioactin or lonomycin A and in peritoneal macrophages treated with lonomycin A was not accompanied by an increment of release of oxygen intermediates. Lipopolysaccharide (LPS) and muramyl dipeptide (MDP) enhanced the release of toxic oxygen intermediates in peritoneal macrophages, but did not have any toxoplasmacidal effect. Adenosine triphosphate (ATP) content increased during Obioactin, MDP or Toxoplasma lysate antigen (TLA) treatment. The actual oxygen consumption of the peritoneal macrophages treated with Obioactin increased dose dependently, but that of TLA-, lonomycin A- or MDP-treated cells did not change. These results suggest that the relationship between the intracellular killing of Toxoplasma protozoa and the release of oxygen intermediates differs according to the cells and/or the stimuli, and that the cellular mechanism of Toxoplasma killing in the peritoneal macrophages treated with Obioactin involves an energy-dependent mechanism.