Hyperexpression of catalase in selenium-deprived murine L1210 cells

Murine leukemia L1210 cells grown for 2-3 weeks in the presence of 1% serum without selenium supplementation [L.Se(-) cells] typically exhibited < 10% of the glutathione peroxidase (GPX) and phospholipid hydroperoxide glutathione peroxidase (PHGPX) activity of selenium-satisfied controls [L.Se(+) cells]. Concomitant with diminished GPX and PHGPX activity was a 1.5- to 2.0-fold increase in catalase (CAT) activity, which reverted to control levels when L.Se(-) cells were given sufficient Se for full expression of selenoperoxidase activity. Selenium manipulation affected total glutathione content similarly, but had no effect on glutathione-S-transferase or superoxide dismutase activity. Long-term growth under Se-deficient conditions resulted in a progressive additional increase in CAT activity, which maximized after ca. 5 months. These cells [referred to as L'.Se(-)] attained CAT activity levels at least 100-times greater than those of Se-supplemented [L'.Se(+)] controls, whereas their glutathione content remained elevated by approximately 70%. Supplying L'.Se(-) cells with Se resulted in a rapid elevation to full GPX activity; however, CAT failed to decline in this case, suggesting that a selection for stable CAT hyperexpressing variants had been accomplished. Quantitative immunoblot analysis indicated that the high CAT activity of L'.Se(-) cells is accounted for by an elevated level of enzyme protein. Induction of CAT and selection for CAT-rich phenotypes, as apparent for Se-starved L1210 cells, was not observed in human K562 counterparts, which lack GPX and express only a low level of PHGPX. L.Se(-) cells were found to be more sensitive to H2O2-induced killing than L.Se(+) controls, whereas L'.Se(-) cells were exceedingly more resistant to H2O2 than L'.Se(+) counterparts. By contrast, L.Se(-) and L'.Se(-) cells were both more sensitive to t-butyl hydroperoxide than Se(+) controls, consistent with CAT being unimportant in the detoxification of this peroxide compared with GPX. This appears to be the first reported evidence for CAT hyperexpression in response to selenium deprivation.

Structural organization of the human gene encoding nuclear lamin A and nuclear lamin C

We have determined the structural organization of the human gene that encodes nuclear lamins A and C, intermediate filament proteins of the nuclear lamina. Sequencing and restriction mapping show that the coding region spans approximately 24 kilobases. The 5'-proximal promoter region contains several GC-rich stretches, a CCAAT box, and a TATA-like element of sequence TATTA. The lamin A/C gene contains 12 exons. Alternative splicing within exon 10 gives rise to two different mRNAs that code for pre-lamin A and lamin C. Consequently, two proteins are generated, only one of which, pre-lamin A, can be modified by isoprenylation. The intron positions in the human lamin A/C gene are generally conserved in the previously characterized genes for Xenopus lamin LIII and mouse lamin B2, but different from those in a Drosophila lamin gene. In the regions coding for the central rod domains, the intron positions are also conserved when compared with the intron positions in the genes for most cytoplasmic intermediate filament proteins except those for nestin and neurofilaments. Analysis of the intron positions in these genes supports the hypothesis that the nuclear lamins and other intermediate filament proteins arose from a common ancestor.

Safety of percutaneous endoscopic gastrostomy in patients with a ventriculoperitoneal shunt

The placement of percutaneous endoscopic gastrostomy tubes in patients with a ventriculoperitoneal shunt implicitly raises concerns about the potential for infection, shunt malfunction, and neurological decompensation. As there is no detailed information on this subject, the safety of percutaneous endoscopic gastrostomy was prospectively studied in 15 consecutive patients who had a ventriculoperitoneal shunt. Ten shunts entered the right upper abdomen, and five were on the left. A percutaneous gastrostomy tube was placed in the left upper abdomen for a minimum of 1 week (mean, 2.2 weeks) after shunt insertion. In the immediate postoperative period, no wound or intra-abdominal complications occurred. One patient developed acute neurological decompensation because of proximal shunt malfunction, and one patient died from cardiopulmonary complications unrelated to the placement of shunts or gastrostomy tubes. Among the 14 survivors, there have been no shunt malfunctions or septic complications during a mean follow-up period of 8.6 months. It would appear that percutaneous endoscopic gastrostomy tubes can be placed in patients with a ventriculoperitoneal shunt without undue concern for short- or long-term infectious or neurological sequelae. In addition, the presence of a shunt on the left side does not necessarily interfere with the safe placement of a percutaneous endoscopic gastrostomy tube.

Comparison in women versus men of composition of atherosclerotic plaques in native coronary arteries and in saphenous veins used as aortocoronary conduits

OBJECTIVES

This study quantifies and compares the components of atherosclerotic plaques in native coronary arteries and in saphenous vein grafts used for aortocoronary bypass surgery in women versus those in men.

BACKGROUND

Plaque composition has been described in various manifestations of fatal coronary artery disease and after the bypass operation, but no reports have investigated this composition according to gender.

METHODS

A total of 979 5-mm segments of native coronary arteries and 842 5-mm segments of saphenous vein grafts were examined by computerized planimetric technique in 11 women and 11 men who were matched for survival time after the bypass operation.

RESULTS

Comparison of the plaque components revealed that atherosclerotic plaques in women, compared with those in men, contained significantly more cellular fibrous tissue, both in native coronary arteries (mean 38% vs. 4%, p < 0.001) and in saphenous vein grafts (mean 70% vs. 36%, p < 0.05). In contrast, the proportion of dense fibrous tissue was significantly less in the atherosclerotic plaques of women than in those of men, both in native coronary arteries (mean 50% vs. 85%, p < 0.001) and in saphenous vein grafts (mean 25% vs. 57%, p < 0.05).

CONCLUSIONS

Cellular fibrous tissue is often found at an early stage of plaque development, whereas dense fibrous tissue is a major component in later stages. Thus, the plaque composition of the native coronary arteries and saphenous venous conduits differed in men and women, with the plaques of the women appearing younger than those of the men.

Planned sexual behaviour of young Australian visitors to Thailand

OBJECTIVE

To research the knowledge of AIDS and other sexually transmitted diseases among young Australian tourists to Thailand, and their intended sexual behaviour.

DESIGN AND SETTING

A cross-sectional survey by anonymous, self-administered questionnaire, of persons seeking pre-travel medical advice in private clinics in five Australian cities.

PARTICIPANTS

213 consecutive patients travelling to Thailand without a spouse or partner.

RESULTS

Only 34% of the sample reported a definite intention not to have sex in Thailand. Regarding choice of potential partners: 24.5% more men than women said they would have sex with a Thai national; 13.7% of men said they would have sex with a "bar girl"; and 21.7% more women than men said they would choose a fellow Australian traveller. Eighty-two per cent of the sample reported that they would use condoms 100% of the time, and there was no significant difference between the number of men and women who expressed this intention.

CONCLUSIONS

Although not obviously "sex tourists", many young Australian travellers are likely to have sex while visiting Thailand. These data have important implications for education and prevention programs to control the spread of human immunodeficiency virus (HIV) and other sexually transmitted diseases.

Selenoperoxidase-mediated cytoprotection against the damaging effects of tert-butyl hydroperoxide on leukemia cells

Murine leukemia L1210 cells grown for 5-7 d in the presence of 1% serum without added selenium [Se(-) cells] expressed < 5% of the glutathione peroxidase (GPX) activity of selenium-supplemented controls [Se(+) cells]. Clonogenic survival assays indicated that t-butyl hydroperoxide (t-BuOOH) is much more toxic to Se(-) cells (LC50 approximately 10 microM) than to Se(+) or selenium-repleted [Se(-/+)] cells (LC50 approximately 250 microM). Hypersensitivity of Se(-) cells to t-BuOOH was partially reversed by treating them with Ebselen, a selenoperoxidase mimetic; thus, selenoperoxidase insufficiency was probably the most serious defect of Se deprivation. Cytotoxicity of t-BuOOH was inhibited by desferrioxamine and by alpha-tocopherol, indicating that redox iron and free radical intermediates are involved. Elevated sensitivity of Se(-) cells to t-BuOOH was accompanied by an increased susceptibility to free radical lipid peroxidation, which became even more pronounced in cells that had been grown in arachidonate (20:4, n-6) supplemented media. That glutathione (GSH) is required for cytoprotection was established by showing that Se(+) cells are less resistant to t-BuOOH after exposure to buthionine sulfoximine (BSO), an inhibitor of GSH synthesis, or 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU), an inhibitor of glutathione reductase. Coupled enzymatic assays indicated that Se(+) or Se(-/+) cells metabolize t-BuOOH 20-25 times more rapidly than Se(-), consistent with the measured difference in GPX activities of these cells. Correspondingly, when challenged with t-BuOOH, Se(+) cells showed an initial loss of GSH and elevation of GSSG that exceeded that of Se(-) cells. It was further shown that like Se(-) cells, BSO- or BCNU-treated Se(+) cells metabolize t-BuOOH more slowly than nontreated controls. These results clearly indicate that selenoperoxidase action in the glutathione cycle is a vital element in cellular defense against toxic hydroperoxides.

Photodynamic action of merocyanine 540 on leukemia cells: iron-stimulated lipid peroxidation and cell killing

Merocyanine 540 (MC540) is a lipophilic photosensitizing dye of biomedical interest in connection with its ability to preferentially inactivate leukemia cells in bone marrow grafts and enveloped viruses in blood products. Evidence that iron plays a role in dye-mediated photokilling is presented in this report. When sensitized with MC540 and irradiated with visible light, cultured murine leukemia L1210 cells underwent lipid peroxidation (accumulation of iodometrically detectable lipid hydroperoxides) and photokilling (loss of clonogenic capacity). Selenium-deficient [Se(-)] cells, which expressed minimal selenoperoxidase activity, were found to be more sensitive to photoperoxidation and photokilling than selenium-replete [Se(+)] controls. Since redox active iron in the presence of electron donors has been shown to exacerbate photoperoxidative damage in isolated membrane systems, it was of interest to examine the possible role of iron in MC540/light-induced cytotoxicity. Involvement of iron was established by showing (i) that desferrioxamine (a high-affinity chelator and redox inhibitor of Fe3+) acted protectively on Se(-) and Se(+) cells and (ii) that treating these cells with sublethal concentrations of the lipophilic chelate ferric 8-hydroxyquinoline [Fe(HQ)2] made them much more sensitive to photokiling and thiobarbituric acid-detectable lipid peroxidation. Lehal damage induced by t-butyl hydroperoxide was also amplified by Fe(HQ)2. Fe(HQ)2-enhanced photoperoxidation and photokilling were suppressed by alpha-tocopherol, suggesting that iron-catalyzed free radical reactions were involved. A mechanism based on iron-mediated one-electron reduction of nascent photoperoxides is proposed. We believe that under the conditions used, toxic one-electron chemistry overwhelms two-electron detoxification catalyzed by GSH-dependent selenoperoxidase(s).

The rightward gas vesicle operon in Halobacterium plasmid pNRC100: identification of the gvpA and gvpC gene products by use of antibody probes and genetic analysis of the region downstream of gvpC

The extreme halophile Halobacterium halobium synthesizes intracellular gas-filled vesicles that confer buoyancy. A cluster of 13 genes on the 200-kb endogenous plasmid pNRC100 has been implicated in the biosynthesis of gas vesicles. Here, we show that two gas vesicle proteins are encoded by genes in the rightward operon, gvpA and gvpC, by Western blotting (immunoblotting) analysis with antibodies directed against LacZ-GvpA and LacZ-GvpC fusion proteins. Our results are consistent with previous data showing that the gvpA gene product is the major gas vesicle protein and demonstrate for the first time that the gvpC gene product is also present in H. halobium gas vesicles. Northern (RNA) blotting analysis showed two RNA species, an abundant 0.35-kb transcript of gvpA and a minor 2.5-kb transcript of gvpAC, and a third gene 3' to gvpAC, named gvpN. The gvpN gene encodes a hypothetical acidic protein with a molecular weight of 39,000 and a nucleotide binding motif. We used a site-directed mutagenesis method involving double recombination in Escherichia coli to insert a kanamycin resistance cassette just beyond the stop codon of gvpN. Introduction of the mutated gene cluster into an H. halobium mutant with a deletion of the entire gas vesicle gene cluster resulted in gas vesicle-positive transformants; this result suggests that gvpN is the last gene of the rightward gas vesicle transcription unit. We discuss the design and utility of the kanamycin resistance cassette for the mutagenesis of other genes in large operons.

[Analysis of 805 children with Salmonellae infection]

We analyzed 805 children with Salmonellae infection admitted during 1981-1991. 353 of them had typhoid fever. Most of the children were over 3 years old and came from rural area. One child died. Those under 3 years of age had non-typhoid Salmonellae infection, manifesting as enteritis pattern; most sepsis patterns were seen in neonates. S. typhimurium was often seen Salmonellae infection, S. agona came next, and S. derby the third. Salmonellae infection varied, including 7 serum groups and 25 serum types. S. typhimurium and S. agona were drug resistant, with severe carrier status. Infants and young children are very liable the infection, therefore, will be the main subjects of prevention.

3-(Phenylamino)alanine, a novel aniline-derived amino acid associated with the eosinophilia-myalgia syndrome: a link to the toxic oil syndrome?

The eosinophilia-myalgia syndrome (EMS) is an inflammatory disease that occurred in epidemic proportions in the United States during 1989. Cases of EMS were also reported in Europe and elsewhere. Clinically, EMS resembles the Spanish toxic oil syndrome. EMS has been associated with ingestion of manufactured L-tryptophan and, more specifically, with lots of tryptophan that contained the trace contaminant 1,1'-ethylidenebis(tryptophan) (EBT). Another trace contaminant ("peak UV-5") has been reported, but the strength of its association with EMS has not been demonstrated. Herein we report independently that peak UV-5 is 3-(phenylamino)alanine (PAA). Patients with EMS ingested significantly greater amounts of both PAA and EBT than did control tryptophan users. PAA is chemically similar to 3-phenylamino-1,2-propanediol, an aniline derivative isolated from samples of oil that were consumed by persons in whom the toxic oil syndrome developed. The discovery of an aniline-derived contaminant in tryptophan raises the possibility that EMS and toxic oil syndrome may have a common etiologic trigger.

Gastroduodenal intussusception secondary to a gastric lipoma: a case report and review of the literature

Gastroduodenal intussusception is an extremely uncommon condition usually caused by the prolapse of a benign gastric tumor into the duodenum with subsequent invagination of a portion of the stomach wall. A rare case of this condition associated with a gastric lipoma is presented. Clinical manifestations may mimic many other disease entities and are nonspecific. Diagnosis, however, can often be made preoperatively with noninvasive tests, which are usually associated with more specific signs. Treatment involves reduction of the intussusception and surgical excision of the lead point, either endoscopically or through a formal laparotomy.

Composition of atherosclerotic plaques in the epicardial coronary arteries in juvenile (type I) diabetes mellitus

The composition of atherosclerotic plaques in 331 five-mm segments of the 4 major (left main, left anterior descending, left circumflex, and right) epicardial coronary arteries of 8 patients with juvenile (mean age at onset, 9 years; mean age at death, 29 years) diabetes mellitus was determined by computerized planimetric analysis. Analysis of all coronary segments disclosed that the plaques consisted primarily of dense (53%) and cellular (38%) fibrous tissue. Pultaceous debris (7%), foam cells (1.2%) and calcific deposits (0.7%) occupied a small percentage of the plaques. Thus, 91% of the coronary plaques in these young diabetic patients consisted of fibrous tissue and nearly all of the remaining 9% consisted of lipid deposits. Analysis of composition according to degrees of cross-sectional luminal narrowing revealed marked increases in dense fibrous tissue (from 31 to 74%), pultaceous debris (from 3 to 12%), and calcific deposits (from 0% to 3%) as the cross-sectional area narrowing increased from < or = 25% to > 75%. Compared with older patients with fatal coronary artery disease, the patients with juvenile diabetes had more dense fibrous tissue and pultaceous debris and less calcific deposits.

Dispersion effects in a single-mode holographic waveguide interconnect system

Dispersion effects in a single-mode holographic waveguide interconnect system are analyzed, and the effect of a wavelength shift in laser diodes owing to the variation of environmental temperature are discussed. It is found that the stringent coupling-in requirement of the single-mode waveguide is the limiting factor of the optical interconnect performance. A novel waveguide grating coupler is thus introduced to eliminate this problem.

Localization of epidermal growth factor and its receptor in mandibular molars of the rat prior to and during prefunctional tooth eruption

Immunoperoxidase localization of epidermal growth factor receptors (EGFR) and epidermal growth factor (EGF) itself was examined in rat first and second mandibular molars postnatally from day 0 to 12. The results showed that the dental follicle stained heavily for EGFR from day 0 to 8, declined in staining at day 9, and was devoid of stain from day 10 onward. Preosteoblasts and osteoblasts of alveolar bone also stained and lesser staining of ameloblasts and odontoblasts was observed. Except for staining of occasional isolated cells, the stellate reticulum did not stain. Light staining of the dental pulp of the first mandibular molar was seen from day 0 onward but the pulp of the second molar did not stain until approximately day 6. With respect to EGF, the dental follicle also stained for it until day 12. The ameloblasts stained more intensely for EGF than for EGFR. Because injections of EGF cause premature eruption of teeth and because the presence of a dental follicle is necessary for eruption, this study suggests that EGF could have its effect on the follicle as seen by the presence of EGFR receptors on the follicle. Moreover, because EGF exerts its effects early (day 0-3) to cause eruption and because the influx of monocytes into the follicle to form osteoclasts for bone resorption for eruption occurs early, the heavy staining for EGFR in the follicle early followed by the absence of staining at day 10 correlates chronologically with the key molecular and cellular events of eruption. Finally, the presence of EGF in the follicle, as well as enamel organ, could provide an endogenous source of EGF to regulate tooth eruption, either by an autocrine or a paracrine effect. Thus, the localization of EGFR and EGF in the dental follicle coupled with the chronology of localization suggests that EGF could play a physiological role in tooth eruption.

Granule proteins of the dental follicle and stellate reticulum inhibit tooth eruption and eyelid opening in postnatal rats

Electron-dense granules within cells of the dental follicle and stellate reticulum of rat mandibular molars can be isolated; their major components are 167 and 200 kDa proteins. Injecting these granule proteins into postnatal rats results in a delay of incisor eruption and eyelid separation. These inhibitory effects were most pronounced with the 167 kDa protein (a delay of 3 days in incisor eruption and of 2 days in eyelid opening) and were opposite to the stimulatory effects of epidermal growth factor. Thus, these granules may play an inhibitory part in tooth eruption.

Isolation of granule proteins from cells of the dental follicle and stellate reticulum of rat mandibular molars

The presence of a dental follicle is required for eruption of teeth of limited eruption but it is uncertain if any molecules indigenous to the follicle regulate this eruption. However, electron-dense granules of unknown composition and function are present in the fibroblasts of the dental follicle of rat molars, as well as the adjacent stellate reticulum, before and during tooth eruption. Here the granules have been isolated; two proteins, of 167 and 200 kDa, have been determined by biochemical and immunological methods to be major components of the granules.

Selenoperoxidase-mediated cytoprotection against merocyanine 540-sensitized photoperoxidation and photokilling of leukemia cells

Photodynamic therapy with the lipophilic sensitizing dye merocyanine 540 (MC540) is a promising new approach for extracorporeal purging of neoplastic cells from autologous remission bone marrow grafts. Resistance-conferring cellular defenses against the cytotoxic effects of MC540/photodynamic therapy have not been well characterized. This study focuses on the cytoprotective effects of the glutathione-dependent selenoperoxidases GPX and PHGPX, which can detoxify a wide variety of hydroperoxides, including lipid-derived species (LOOHs). Murine leukemia L1210 cells were grown in 1% serum media without [L.Se(-)] and with [L.Se(+)] selenium supplementation. L.Se(-) cells expressed 10- to 20-fold lower GPX and PHGPX activities than L.Se(+) controls and were markedly more sensitive to MC540-mediated photoperoxidation (LOOH formation) and clonally assessed photokilling. Susceptibility of L.Se(-) cells to photoperoxidation and photokilling could be fully reversed to L.Se(+) levels by replenishing Se, and partially reversed by treating with Ebselen, a selenoperoxidase mimetic. Altered lipid composition, greater uptake of MC540, and defective catabolism of H2O2 were all ruled out as possible factors in the elevated photosensitivity of L.Se(-) cells. Human leukemia K562 cells (capable of expressing PHGPX but not GPX) exhibited 5- to 10-fold lower PHGPX activity under Se-deficient relative to Se-sufficient conditions. Although MC540 uptake (nmol/mg lipid) by K562 and L1210 cells was essentially the same, the former were more resistant to photoinactivation. However, like murine counterparts, Se-deficient cells were more susceptible to photoperoxidation and photokilling than Se-sufficient controls. These results clearly demonstrate that GPX and/or PHGPX in L1210 cells and PHGPX in K562 cells play an important cytoprotective role during photooxidative stress. Whether membrane damage due to lipid photoperoxidation is causally related to cell death is not certain; however, the parallel effects of Se deficiency on LOOH formation and cell killing are at least consistent with this possibility.

Detection of circulating antigen by McAb-AST for evaluating the efficacy of anti-Leishmania chemotherapy

We have adapted the simple and sensitive McAb-antigen spot test (AST) for evaluating the efficacy of anti-Leishmania chemotherapy. Serum samples from 37 kala-azar patients were tested by McAb-AST, and all showed definite positive reactions before treatment. After a course of antimony treatment, 20 turned negative, coupled with the disappearance of clinical symptoms; another 12 cases responded with weak positivity accompanied by an improvement of clinical manifestations; and the remaining 5 antimony-resistant patients showed strong positive reactions, with their conditions gradually worsening. Furthermore, all 6 cases in which the diagnosis was missed by the bone marrow smear method turned McAb-AST negative after chemotherapy. These results suggest that McAb-AST can be used to evaluate the efficacy of chemotherapy as well as to avoid missed diagnosis by the bone marrow smear method.

[Reduction mammaplasty]

Twenty-eight breasts of 15 patients with macromastia underwent reduction mammaplasty from 1982 to 1989. We followed up these patients postoperatively for 6 months to 7 years. The follow-up time for 8 patients was over 1 year, and 4 patients over 5 years. And 3 patients labored and lactated. These 15 patients were satisfied with this operative results. The operative technology was based on Pitange's method. This method improved the site of the nipple, transposition of nipple-areola complex, and design of dermal pedicle, so that it had better effects in the breast shape, breast fixation and incision scar concealed. We suggest that the purpose of macromastia treated in reducing volume, improving breast shape, preserving lactating function. This paper also discusses the methods for nipple site, nipple-areola complex transposition, breast resection and mastopexy.

Effects of transforming growth factor-beta 1 on cultured dental follicle cells from rat mandibular molars

Analysis of the total proteins secreted by cultured dental follicle cells revealed that transforming growth factor-beta 1 (TGF-beta 1) stimulated them to secrete more extracellular matrix proteins into a serum-free medium than did follicle cells not exposed to the growth factor. Electrophoresis and scanning densitometry showed that secretion of all the major proteins was increased by exposure to the growth factor but the amounts ranged from a 66% increase for one of the procollagen chains to a 7% increase for fibronectin. Immunofluorescence using anti-type I collagen and anti-fibronectin showed that the intracellular concentration and intracellular localization of the antibodies was not changed by incubating the cells with the growth factor. The growth factor did not cause an increase in cell number but did modify the association of the cells in the culture, causing them to aggregate into clusters whereas the control cells formed a confluent monolayer. These results suggest that TGF-beta 1 may signal the fibroblasts of the dental follicle to secrete the extracellular matrix needed for its development into a periodontal ligament.

Multiplexed holographic Fabry-Perot étalons

We discuss a multiplexed holographic Fabry-Perot étalon that includes a multiplexed hologram in a novel holographic Fabry-Perot étalon. Two unique advantages can be achieved by using the multiplexed holographic Fabry-Perot étalon: coherently coupled fabrication of holographic Fabry-Perot mirrors significantly reduces the need to have the nearly flat surfaces typically required in conventional Fabry-Perot etalons, and the angular-wavelength multiplexing capability of a multiplexed hologram can be added to the tunable narrow-band filtering capability of Fabry-Perot étalons. Several types of multiplexed holographic Fabry-Perot étalon are experimentally demonstrated.

Breast cancer with extensive intraductal component: treatment with immediate interstitial boost irradiation

Extensive intraductal component (EIC) has been reported to have a prominent role in local recurrence after treatment of early-stage breast cancer with lumpectomy and irradiation. Pathologic specimens from 250 breasts (245 patients) treated between June 1982 and June 1990 with lumpectomy, immediate (boost) interstitial iridium-192 to 15-20 Gy, and external-beam irradiation to the entire breast to 45-50 Gy were reviewed. EIC was present in 61 breasts. At a median follow-up period of 58 months (range, 14-110 months), there were 10 recurrences in the 250 treated breasts. Of these 10, three were in patients from the group with EIC. The 10-year actuarial recurrence rates in breasts with and without EIC were 9.1% and 5.2%, respectively. The difference between the two rates was not significant. If an immediate boost with interstitial iridium is used in therapy, the influence of EIC on local failure is insignificant.

Culture and characterization of dental follicle cells from rat molars

Because the dental follicle is necessary for the eruption of teeth of limited eruption, it was the objective of this study to determine if the cells of the follicle could be cultured in vitro. To achieve this, dental follicles and associated enamel organs were dissected from the first and second mandibular molars of 6-7-day-old rats (secretory stage of amelogenesis), and then cultured in a medium that promotes fibroblast growth--the predominant cell type of the dental follicle. The cultured cells grew to confluency and were kept through 3 passages before experimentation. The cultured cells were fibroblastic in shape, elongate with processes, and transmission electron microscopy revealed that they contained an abundant rough endoplasmic reticulum, but did not form desmosomes. Immunofluorescent staining for anti-vimentin showed that all the cells stained and electron-microscopic immunogold labeling indicated that the antibody was associated with intermediate filaments. As revealed by SDS-polyacrylamide gel electrophoresis and Western blotting, the cultured cells synthesized and secreted the extracellular matrix molecules fibronectin and procollagens. Subsequent immunofluorescence staining of permeabilized and non-permeabilized cells confirmed the presence of fibronectin and type I collagen both intra- and extracellularly. Thus, based on all the above characteristics, the cultured cells appeared to be fibroblasts derived from the dental follicle, although a few of the fibroblasts may be derived from undifferentiated mesenchymal cells interposed between the alveolar bone and follicle. Experiments now can be conducted to determine how these cultured cells respond directly to growth factors that alter the rates of tooth eruption.