Effect of strain on human keratinocytes in vitro

Tissue expansion, a technique to enlarge the skin surface area with an expandable balloon, has been widely used in reconstructive surgery. Although the effect of tissue expansion on in vivo skin physiology and histology has been well documented, it remains unclear whether keratinocytes or other cell types are responsible for these changes. Therefore, we investigated the in vitro effect of cyclic (10 cycles/min, 150 mmHg) or constant (continuous, 150 mmHg) strain on human keratinocyte phenotype and relevant mechanosignaling pathways. Our results demonstrate that keratinocytes subjected to cyclic strain exhibit a significant (P < 0.05) increase in cell proliferation (49.2+/-15.8%), DNA synthesis (37.7+/-4.5%), elongation (20.3+/-2.7%), and protein synthesis (17.9+/-6.6% increase) as compared with stationary controls. In contrast, keratinocytes subjected to constant strain were unaffected aside from a modest transitory increase in the proliferative rate. Keratinocytes subjected to cyclic strain aligned perpendicular to the force vector (24.2+/-1.6 degrees) as compared with stationary controls (40.4+/-2.2 degrees; the smaller degree indicates better alignment). We also report strain-induced reduction in the levels of cyclic adenosine mono phosphate (cAMP), protein kinase A (PKA), and prostaglandin E2 (PGE2) as compared with stationary controls (cAMP, 30+/-7.5%; PKA, 45+/-17%; PGE2, 58+/-4.3%; percent decrease vs. that of control). We conclude that direct application of cyclic strain on human keratinocytes modulates cell phenotype and cAMP-mediated signaling pathways in an inverse manner. Moreover, keratinocytes may play an important role in previously observed alterations in skin properties associated with tissue expansion and other strain-induced responses.

Effect of strain on human keratinocytes in vitro

Tissue expansion, a technique to enlarge the skin surface area with an expandable balloon, has been widely used in reconstructive surgery. Although the effect of tissue expansion on in vivo skin physiology and histology has been well documented, it remains unclear whether keratinocytes or other cell types are responsible for these changes. Therefore, we investigated the in vitro effect of cyclic (10 cycles/min, 150 mmHg) or constant (continuous, 150 mmHg) strain on human keratinocyte phenotype and relevant mechanosignaling pathways. Our results demonstrate that keratinocytes subjected to cyclic strain exhibit a significant (P < 0.05) increase in cell proliferation (49.2+/-15.8%), DNA synthesis (37.7+/-4.5%), elongation (20.3+/-2.7%), and protein synthesis (17.9+/-6.6% increase) as compared with stationary controls. In contrast, keratinocytes subjected to constant strain were unaffected aside from a modest transitory increase in the proliferative rate. Keratinocytes subjected to cyclic strain aligned perpendicular to the force vector (24.2+/-1.6 degrees) as compared with stationary controls (40.4+/-2.2 degrees; the smaller degree indicates better alignment). We also report strain-induced reduction in the levels of cyclic adenosine mono phosphate (cAMP), protein kinase A (PKA), and prostaglandin E2 (PGE2) as compared with stationary controls (cAMP, 30+/-7.5%; PKA, 45+/-17%; PGE2, 58+/-4.3%; percent decrease vs. that of control). We conclude that direct application of cyclic strain on human keratinocytes modulates cell phenotype and cAMP-mediated signaling pathways in an inverse manner. Moreover, keratinocytes may play an important role in previously observed alterations in skin properties associated with tissue expansion and other strain-induced responses.

Characterization of poly-leucine substituted analogues of the human surfactant protein SP-C

A series of novel amphipathic peptides constituted of an N-terminal hydrophilic portion (CPVHLKR, residues 6-12) of human pulmonary surfactant protein-C (SP-C) and a poly-leucine (poly-L) stretch of various chain lengths as the C-terminal hydrophobic tail were synthesized and evaluated relevant to their ability to improve the surface activity of a ternary lipid mixture composed of dipalmitoylphosphatidylcholine, egg-phosphatidylglycerol and palmitic acid (DPPC/E-PG/PA, 75:25:10, w/w) in a Langmuir-Wilhelmy surface balance. CPVHLKRL11, a human SP-C analogue bearing an 11-residue poly-L tail, and its related peptides with longer tails in the ternary lipid mixture, accelerated not only the surface spreading at the air-water interface but also exhibited significantly improved dynamic surface activity, compared to the ternary lipid mixture. Their surface activities were almost indiscernible from those of the synthetic human SP-C. When reconstituted into a ternary lipid mixture containing members of the homologous series of n-saturated diacylphosphatidylglycerol, the surface activities of the poly-L analogues were almost completely unaffected, whereas replica peptides carrying the hydrophobic portion of native SP-C were found to have distinct surface activities depending upon the acyl-chain lengths of phosphatidylglycerol. The poly-L stretch of a poly-L analogue could be replaced with poly-norleucine of the same chain length without a significant loss of surface activity. Substitution of the poly-L portion in the analogues with poly-valine or poly-isoleucine resulted in a considerable decrease in surface activity. The poly-L analogue in the DPPC/E-PG/PA mixture was demonstrated to act as an excellent surfactant comparable with Surfacten, a modified bovine surfactant preparation that was used for treatment for infant respiratory distress syndrome, based on evaluation of the lung pressure-volume characteristics using premature rabbit neonates.

Enhancement of Ca2+ currents by GHRH and its relation to PKA and [Ca2+]i in human GH-secreting adenoma cells

The effects of human growth hormone-releasing hormone (hGHRH) on Ca2+ channels were examined in human growth hormone-producing adenoma cells using the perforated whole cell clamp technique. These cells exhibited T- and L-type Ca2+ channel currents, and application of 10(-8) M hGHRH increased the amplitude of both currents. Application of 10(-5) M 8-bromoadenosine 3',5'-cyclic monophosphate also increased T- and L-type currents. Additional application of 10(-8) M hGHRH did not further increase the current amplitudes. Treatment with the Rp diastereomer of adenosine 3',5'-cyclic monophosphothioate (10(-5) M) or H-89 (10(-5) M) inhibited the enhancement of Ca2+ channel currents by hGHRH, as did intracellular injection of protein kinase A (PKA) inhibitor peptide [PKI-(5-24)], indicating that hGHRH increased the amplitude of Ca2+ channel currents through the activation of the adenosine 3',5'-cyclic monophosphate (cAMP)-PKA system. When intracellular Ca2+ concentration ([Ca2+]i) was chelated to < 30 nM with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid acetoxymethyl ester (BAPTAAM), hGHRH failed to increase the Ca2+ channel currents. In this condition, hGHRH activated nonselective cation channels, which revealed that the cAMP-PKA system operated after treatment with BAPTA-AM and that the site of low [Ca2+]i-induced inhibition of hGHRH effects on Ca2+ channels was at a step after PKA activation.

Treatment of pathologic fracture and surgical value of prognostic factors in multiple myeloma

Fifty-eight cases diagnosed as multiple myeloma were reviewed to assess the surgical treatment and prognostic factors which had been recently advocated to predict the survival. The following data in these cases were investigated: age, sex, surgical modalities and prognostic factors such as beta 2-microglobulin, LDH, hemoglobin, etc. In our study, surgical significance based on these laboratory findings was discussed. There was significant difference (p < 0.05) in hemoglobin level between pathologic fracture group and non-fracture group. The albumin in the fracture group was lower than the albumin in the non-fracture group. These data were consistent with increased activity of myeloma cells that might cause bone destruction and fracture. Multiple myeloma has a peak incidence during the 7th decade, younger patients (< or = 40 yrs.o.) were rare. One 39-year-old man was successfully treated with surgery, chemotherapy and radiation therapy. Operative intervention seems to be quite important to improve the quality of life if longer survival is expected.

The surface properties of chemically synthesized peptides analogous to human pulmonary surfactant protein SP-C

A number of peptides with different lengths corresponding to various regions of human pulmonary surfactant protein SP-C were synthesized and their activity evaluated to improve in vitro surface activities and in situ lung pressure-volume characteristics of a ternary lipid mixture composed of dipalmitoylphosphatidylcholine, phosphatidylglycerol and palmitic acid (75:25:10, w/w). SP-C (1-35), a synthetic peptide with the entire length of human SP-C, and some other peptides with various lengths of its partial sequences were remarkably active. All of these peptides shared a common core sequence of (C)CPVHLKRLLIVVVVVVLIVVVIVGAL(L). Any deletion in this core sequence resulted in reduction of activity of the peptide. SP-C (5-31) and SP-C (6-32), the minimum peptides containing the core sequence, were combined with the ternary lipid mixture at the final peptide concentration of 2% (w/w) into synthetic surfactants which showed excellent properties comparable with those of Surfacten, a commercially available modified bovine lung surfactant. In a Langmuir-Wilhelmy surface balance, the synthetic surfactant containing SP-C (6-32) spread and adsorbed quickly to reach a surface tension of 30.8 mN/m at 30-s spreading time and 41.2 mN/m at 1-min adsorption time, respectively; the presence of SP-C (6-32) significantly prevented the decrease of surface activity of the ternary lipid mixture during dynamic compression-expansion cycles. Furthermore, tracheal instillation of the synthetic surfactant containing SP-C (6-32) at the dose of 50 mg of phospholipids/kg improved lung pressure-volume characteristics of immature rabbit neonates to a level similar to that of mature neonates at term.

Ectrodactyly, ectodermal dysplasia, and cleft lip syndrome. Case report

We describe five sporadic cases of the EEC syndrome (ectrodactyly, ectodermal dysplasia, and cleft lip). There are only a few reports of the syndrome being inherited in Japan. Two of the five patients had genitourinary anomalies and one mental retardation. Four of the five patients had clefts in the primary and secondary palate. All had deformities of the hands, polydactyly, syndactyly, and camptodactyly. Syndactyly could be a component of the syndrome.

GHRH activates a nonselective cation current in human GH-secreting adenoma cells

Electrophysiological responses induced by human (h) growth hormone-releasing hormone (GHRH) were analyzed using the perforated whole cell clamp technique in human growth hormone (GH)-secreting adenoma cells. Application of hGHRH depolarized the membrane by increasing Na+ conductance. The reversal potential of the hGHRH-induced current was -20 to 0 mV. The channel was permeable to Na+, Li+ and K+ but not to TMA+. These properties were compatible with those of nonselective cation channels. Similar nonselective cation current was activated by 8-bromoadenosine 3',5'-cyclic monophosphate and forskolin, and the activation of the hGHRH-induced current was inhibited by protein kinase A (PKA) inhibitors, (R)-p-adenosine 3',5'-cyclic monophosphate and N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinoleinsulfonamide, and PKA inhibitor peptide PKI-(5-24), indicating that hGHRH-induced current was activated by PKA. Cholera toxin pretreatment eliminated the hGHRH-induced current, suggesting that Gs is involved in the activation of this current. This current became irreversible when the cells were pretreated with okadaic acid, suggesting that the recovery of the hGHRH-induced current was mediated by a serine/threonine protein phosphatase. GHRH-induced GH secretion was inhibited in Na+-free medium, suggesting the importance of the nonselective cation current on hGHRH-induced GH secretion. In human GH-secreting nonadenoma cells, hGHRH increased Na+ conductance, as was the case in GH-secreting adenoma cells.

Mutagenicity studies with palm fruit carotene

The mutagenicity of palm fruit carotene was examined using the reverse mutation test with bacteria, the chromosomal aberration test with mammalian cells and the micronucleus test in mice. The carotene induced neither reverse mutation in Salmonella typhimurium TA98, TA1537, TA100, TA1535 and in Escherichia coli WP2uvrA, nor structural and numerical (polyploidy) chromosomal aberrations in the Chinese hamster fibroblast cell line (CHL). In addition, no increase in micronucleated polychromatic erythrocytes was elicited in the micronucleus test in CD-1(ICR) male mice. It is concluded that palm fruit carotene had no mutagenic activity in these in vitro and in vivo tests.

Hydroxyapatite clay for gap filling and adequate bone ingrowth

In uncemented total hip arthroplasty, a complete filling of the gap between femoral prosthesis and the host bone is difficult and defects would remain, because the anatomy of the reamed intramedullary canal cannot fit the prosthesis. Therefore, it seems practical to fill the gap with a clay containing hydroxyapatite (HA), which has an osteoconductive character. The clay (HA clay) is made by mixing HA granules (size 0.1 mm or more) having a homogeneous pore distribution and a porosity of 35-48 vol%, and a viscous substance such as a saline solution of sodium alginate (SSSA). In the first experiment, the ratio of HA granules and sodium alginate in SSSA is set for the same handling properties of HA clay and polymethylmethacrylate bone cement (standard viscosity) before hardening. As a result, the ratio is set for 55 wt% of HA in the clay and 12.5 wt% of sodium alginate in SSSA (i.e., HA:sodium alginate:saline solution = 9.8:1:7). In the second study, the gap between the femoral stem and bone model is completely filled with HA clay. However, the gap is not filled only with HA granules or HA granules mixed with saline solution. In the third animal experiment, using an unloaded model, histology shows that HA clay has an osteoconductive property bridging the gap between the implant and the cortical bone without any adverse reaction. HA clay is considered a useful biomaterial to fill the gap with adequate bone ingrowth.

Comparison of bitemarks in foodstuffs by computer imaging: a case report

Police called to investigate a fire in a snackbar in Mount Gambier, South Australia, discovered four cakes with characteristics marks apparently produced by human teeth. These marks were examined and compared with the teeth of a suspect arsonist. The comparison was made by computer imaging analysis and a remarkable similarity in arch shape was observed.

Change of salivary IgA secretion and caries development in irradiated rats

Xerostomia is a serious side-effect of radiotherapy for head and neck cancer and often enhances caries activity. However, the relationship between caries induction and the IgA level in saliva in rats subjected to irradiation of the salivary glands is unclear. The effect of salivary gland irradiation on salivary function was examined in specific pathogen-free Sprague-Dawley rats infected with or without Streptococcus mutans MT8148R (serotype c). The flow rate of saliva and the protein concentration in saliva were significantly reduced in irradiated rats, regardless of infection of S. mutans. The caries activity was enhanced in these rats, and and irradiation level of 50 Gy significantly increased the caries score. However, longitudinal study indicated that the salivary concentration of IgA reactive with S. mutans whole cells maintained similar or significantly higher levels in irradiated rats, when compared with those of nonirradiated rats. In addition, there was no negative correlation between the caries score and the salivary concentration of IgA reactive with S. mutans. These findings suggest that the secreted IgA against S. mutans may not play a significant role in the caries induction of hyposalivated rats.

[A case of marked eosinophilia in peripheral blood induced by rhGM-CSF]

A 53-year-old man underwent chemotherapy (CDDP, VDS, MMC) for treatment of lung cancer. He was given 125 micrograms/m2 of GM-CSF subcutaneously every day for 8 consecutive days, in order to prevent neutropenia. Three days after starting GM-CSF therapy, marked eosinophilia in peripheral blood was observed. The maximum eosinophil count was 89% of leukocytes. Nine days after stopping the treatment with GM-CSF, the number of eosinophils had normalized spontaneously. There were no clinical symptoms except for slight fever, up to 37.5 degrees C. Moreover, there was no relationship between the number of eosinophils and the serum levels of cytokines (IL-3, IL-5, GM-CSF), although we observed minimal but significant elevation of serum ECP level. This case indicates that GM-CSF may induce marked eosinophilia rather than widely stimulating granulocytes and monocytes.

[Sex determination with a discriminant function analysis of deciduous teeth size in plaster models]

Plaster models of the teeth of 3-year-old Japanese children (96 males, 98 females) were used to record the crown length, crown width and crown thickness of 5 maxillary and 5 mandibular deciduous teeth (30 measurement values). These measurements were used to devise a number of sex determination formulae. A sex-determination formula using all 30 values was calculated. Furthermore, a number of practical formulae were derived from only the crown width and crown thickness values because the deciduous teeth wear in 4 years and older children rapidly progress, making the crown length measurement unreliable. These formulae were calculated for the maxillary teeth alone and mandibular teeth alone. The formulae based on only the crown width or thickness were also calculated for both maxillary and the mandibular teeth. A step-wise discriminant analysis was then used to ascertain the most reliable measurements and a practical formula subsequently devised. The results obtained were as follows: 1. The mean value for each measurement was greater in males than in females. 2. Significant differences in the values recorded were seen in 28 out of the 30 measurements taken. The measurement items not exhibiting these significant differences were the crown width of the maxillary lateral incisor and the crown thickness of the mandibular second molar. 3. The accuracy rates for the sex-determination analysis and the step-wise sex determination analysis calculated using all 30 values were 78.6% and 75.7%, respectively. 4. The accuracy ranges for the modified sex-determination formulae and the associated step-wise sex determination analyses were 70.6-78.4% and 67.0-76.8%, respectively.

Is personality involved in the expression of dysmenorrhea in patients with endometriosis?

OBJECTIVE

To investigate whether a relationship exists between personality and expression of pain in women with endometriosis.

STUDY DESIGN

With use of the Rosenzweig picture frustration study, the personality of women with endometriosis was assessed. These results were then correlated with the manifestation of pain.

RESULTS

Women without dysmenorrhea tended to be less assertive compared with women who complained of dysmenorrhea and women without endometriosis. Those women without dysmenorrhea showed a destructive attitude in face of a problem.

CONCLUSIONS

Personality affected the expression of pain. Pain caused by endometriosis was influenced by each personality type.

[Identification of artificial teeth by fluorescent examination with an emphasis on metal bond porcelains]

Artificial teeth look similar to natural teeth under natural light, but under the black light blue or fluorescent light (365 nm, 254 nm), they showed different features from those of natural teeth. These characteristic are available to identify various dental porcelain products. Using the metal bond porcelains produced by different manufacturers, we prepared samples showing the same color tone as that of the VITASHADE A3, and examined then with the black light blue or fluorescent examination lamp (365 nm, 254 nm). The results suggest possibility of discrimination of several porcelain products; Ceramco II, Vintage, Vita VMK68, Duceram, Noritake and Biodent. We applied this method to identify porcelain products of coronae on the anterior teeth of unknown bodies in four actual cases.

Genetic diversity within isolates of mutans streptococci recognized by an rRNA gene probe

A total of 79 clinical isolates of mutans streptococci and five laboratory strains representing serotypes c, d, e, f, and g were genotyped by a nonradioactive hybridization method with the rrnB rRNA operon of the Escherichia coli chromosome as a probe. The hybridization patterns of chromosomal DNA fragments obtained by digestion with restriction endonucleases HindIII, SmaI, and BamHI revealed genotypic heterogeneity among the serotypes and among isolates of the same serotype recovered from unrelated subjects. Diversity also existed among isolates obtained from a single subject. For 5 of 13 subjects studied, two or three genotypes within serotypes were found, while eight subjects harbored the same number of genotypes as serotypes. The data show that the method utilizing the rRNA gene probe is of value in determining the molecular epidemiology of isolates of mutans streptococci.

Release behaviour of 5-fluorouracil from chitosan-gel microspheres immobilizing 5-fluorouracil derivative coated with polysaccharides and their cell specific recognition

In order to provide a device releasing drugs in a controlled manner and having targetability to specific organs or cells, chitosan-gel microspheres, CMS, crosslinked with glutaraldehyde, immobilizing 1-[N-(5-aminopentyl) carbamoyl]-5-fluorouracil, 1, coated with anionic polysaccharides, such as 6-O-carboxymethyl-N-acetyl-alpha-1,4-polygalactosamine (CM-NAPGA), 6-O-carboxymethyl-chitin, alginic acid and heparin, by polyelectrolyte complex membrane formation were prepared. When chitosan was crosslinked with glutaraldehyde, 1 was simultaneously immobilized into CMS by Schiff's base formation. Average diameter of CMS obtained was estimated to be about 0.5-1.0 micron by SEM observation. In physiological saline media, only free 5-FU was released from the CMS but 1 and any 5-FU derivative was not. Release rate of 5-FU from the CMS was reduced by coating with polyelectrolyte complex membrane of cationic chitosan and anionic polysaccharides. CMS coated with CM-NAPGA showed a lectin-mediated specific aggregation phenomenon by addition of Abrus precatorius agglutinin. Moreover, the CMS immobilizing 1 coated with CM-NAPGA showed higher growth-inhibitory effect against SK-Hep-1 (human hepatoma) cells in vitro than the CMS coated with other polysaccharides.

Changes with time in the oral microflora and dental caries induction in hyposalivated rats fed on sucrose diet

The effects of hyposalivation on the induction of dental caries and the change in oral microflora were examined at weekly intervals in Sprague-Dawley rats fed on diet 2000 containing 56% sucrose. In hyposalivated rats, significant dental caries was induced within one week and its severity increased with the experimental period. Bacteriological examinations demonstrated that the number of total cultivable microorganisms, lactobacilli and Staphylococcus aureus increased significantly shortly after surgical induction of hyposalivation, while the number of streptococci and yeasts did not increase significantly until the 7th week, beyond which time remarkable gross caries developed. A positive correlation was found between the caries score and the recovery of lactobacilli from mandibles of hyposalivated rats, while there was no statistically significant correlation between the caries score and the recoveries of S. aureus. On the other hand, dental caries was not induced in control rats fed on sucrose diet with no surgically-induced hyposalivation. It was also found that the number of lactobacilli increased significantly shortly after diet 2000 was given to control rats, but S. aureus was rarely recovered from the mandibles of control rats throughout the experiments. The roles of lactobacilli and S. aureus in the induction of dental caries under the hyposalivated condition were discussed and it was suggested that lactobacilli may play some significant role in the induction of dental caries in hyposalivated rats.

[The factors that influence intraoperative blood loss during total hip replacement]

Fifty cases of total hip replacement performed by one surgeon were reviewed to compare the effects of epidural and general anesthesia. The blood pressure in patients under epidural anesthesia was significantly lower (P less than 0.001; t-test). There was a highly significant correlation between the operation time and the intraoperative blood loss (P less than 0.005, r = 0.67). A significant correlation was noted between the blood pressure and the minute loss of blood (P less than 0.01, r = 0.43). It is concluded that epidural anesthesia is to be recommended rather than general anesthesia in patients undergoing total hip replacement.

[The significance of myelodysplasia in untreated patients with multiple myeloma]

Microscopic analysis of bone marrow smears from ten untreated patients with multiple myeloma (MM) revealed that seven patients had myelodysplastic changes. Of these, five patients had anemia alone while the other two had anemia and leucopenia. The myelodysplastic changes seen in MM were less extensive than those seen in myelodysplastic syndrome (MDS). Moreover, the dysplastic changes in MM were determined to be limited to two or three lineage cells. Dysplastic changes were observed even after clinical signs of MM had improved due to therapy. We consider that the myelodysplastic changes seen in MM can be attributed to MM itself, rather than to the coexistence of MDS and MM. Such findings suggest that the pathogenesis of MM involves a common stem cell which differentiates into multiple lineage cells.

Latex agglutination test for detection of mutans streptococci in relation to dental caries in children

A simple and rapid system based on a latex agglutination (LA) reaction was devised for the detection of mutans streptococci in dental plaque. Latex particles were sensitized with antibodies against whole cells of Streptococcus mutans strains MT8148 (serotype c), MT703R (e) and OMZ175 (f) and Strep. sobrinus strains B13 (d) and 6715 (g). These sensitized particles were agglutinated within a few minutes after addition of 1.0-10 ng serotype-specific antigen from the homologous organisms or the nitrous acid extract of whole cells at 10(5)-10(6) c.f.u. The LA test specifically differentiated not only mutans streptococci from the other oral streptococci but also Strep. sobrinus from Strep. mutans. The LA test was also applicable to extracts of plaque from 206 human subjects who harboured mutans streptococci. In clinical trials, the outcome of the LA test correlated significantly with the number of mutans streptococci found in plaque (p less than 0.0001), which was quantified by the selective cultivation of mutans streptococci. Furthermore, the LA test discriminated between Strep. mutans and Strep. sobrinus from human dental plaque. The sensitivity and the specificity of the LA test for detection of mutans streptococci were 78.9 and 100%. The degree of reactivity in the LA test correlated significantly with the number of decayed tooth surfaces (p less than 0.0001) and decayed and filled tooth surfaces (p less than 0.0001). These results suggest that the LA test could be useful clinically for the detection of mutans streptococci in dental plaque as well as serving as a caries-activity test.

Mutacin activity of strains isolated from children with varying levels of mutants streptococci and caries

A total of 157 isolates of mutants streptococci from plaque and saliva of 94 children were studied for their serotypes, mutacin production, frequency and spectrum of activity. Of these isolates 71% were identified as serotype c and 22% as serotype e. Serotypes f, d and g, and one untypable strain made up about 7% of the isolates. More than one serotype was found in 13% of the children. Mutacin was produced by 83% of the isolates against one or more of the 14 indicator strains representing mutants streptococci. Streptococcus sanguis, Strep. oralis, Strep. gordonii, Strep. salivarius and Strep. pyogenes. Isolates that had a broad inhibitory spectrum also produced larger inhibition zones than isolates that inhibited fewer strains. When evaluating the effect of mutacin in vivo on plaque ecology, it was found that the counts of mutans streptococci or the proportion of mutans streptococci in the total streptococcal count of plaque did not differ between plaques containing strains that produced much mutacin and those with little production. The findings also failed to reveal an association between caries experience and mutacin activity.

Venous air embolism during knee arthrography. A case report

A 34-year-old man developed a nonfatal venous air embolism during arthrography of his post-traumatically contractured knee joint. From the arthrographic findings, injected air was assumed to have entered the great saphenous vein via the venous opening in the knee joint. Venous air embolism is an extremely rare complication of knee arthrography, but can occur. As it is potentially fatal, prompt recognition and appropriate positional and supportive therapy are essential.

[Caries-inducing activity of soybean-oligosaccharide (SOR) in vitro and in experimental dental caries of rats]

The caries-inducing activity of soybean-oligosaccharide (SOR: stachyose- and raffinose-rich sugar mixture) was examined in in vitro and in vivo experiments. Streptococcus mutans MT 8148R fermented SOR and produced acids. However Streptococcus sobrinus 6715 did not ferment. SOR was not able to act as a substrate for crude glucosyltransferases (GTase) of these mutans streptococci to synthesize the water-insoluble glucan. However, SOR did not inhibit the synthesis of water-insoluble glucan from sucrose by crude GTase. SOR was proved to be of low cariogenicity in rats infected with S. sobrinus 6715.