Validation and discussion of clinical practicability of the 2022 graded prognostic assessment for NSCLC adenocarcinoma patients with brain metastases in a routine clinical cohort

Introduction

The goal of this analysis is to validate the 2022 graded prognostic assessment (GPA) for patients with brain metastases from adenocarcinoma of the lung and to discuss its clinical practicability.

Methods/material

137 patients with adenocarcinoma of the lung were included in this analysis. The disease specific GPA for NSCLC, Lung-molGPA and the GPA for NSCLC adenocarcinoma were calculated. Overall survival was calculated for each GPA group. Additionally, expected and actual OS in the prognostic groups of the GPA available at the time of the patients' diagnosis was compared.

Results

Median overall survival (OS) from diagnosis of brain metastases was 15 months (95% confidence interval (CI) 9.7-20.3 months). The median OS in the three individual prognostic groups was 7 months for GPA 0-1, 16 months for GPA 1.5-2, 33 months for GPA 2.5-3 and not reached for GPA 3.5-4 (p<0.001). Median survival times for the individual groups were similar to those published in the original GPA publication. Regarding the expected and actual OS when using the available GPA at the time of diagnosis there was an underestimation of survival of more than 3 months for all except the worst prognosis group.

Conclusion

We were able to validate the 2022 GPA for NSCLC adenocarcinoma patients with brain metastases in a similar cohort from a non-academic center. However, the practical applicability regarding the expected median OS might be limited due to the constantly evolving treatment landscape and the consecutive improvement in overall survival.

Treatment of multiple adjacent RT 1 gingival recessions with the modified coronally advanced tunnel (MCAT) technique and a collagen matrix or palatal connective tissue graft: 9-year results of a split-mouth randomized clinical trial

OBJECTIVES

To evaluate t he long-term outcomes following treatment of RT 1 multiple adjacent gingival recessions (MAGR) using the modified coronally advanced tunnel (MCAT) with either a collagen matrix CM or a connective tissue graft (CTG).

MATERIAL AND METHODS

Sixteen of the original 22 subjects included in a randomized, controlled split-mouth clinical trial were available for the 9-year follow-up (114 sites). Recessions were randomly treated by means of MCAT + CM (test) or MCAT + CTG (control). Complete root coverage (CRC), mean root coverage (MRC), gingival recession depth (GRD), probing pocket depth (PD), keratinized tissue width (KTW), and thickness (KGT) were compared with baseline values and with the 12-month results.

RESULTS

After 9 years, CRC was observed in 2 patients, one in each group. At 9 years, MRC was 23.0 ± 44.5% in the test and 39.7 ± 35.1% in the control group (p = 0.179). The MRC reduction compared to 12 months was - 50.1 ± 47.0% and - 48.3 ± 37.7%, respectively. The upper jaw obtained 31.92 ± 43.0% of MRC for the test and 51.1 ± 27.8% for the control group (p = 0.111) compared to the lower jaw with 8.3 ± 46.9% and 20.7 ± 40.3%. KTW and KGT increased for both CM and CTG together from 2.0 ± 0.7 to 3.1 ± 1.0 mm (< 0.0001). There were no statistically significant changes in PD.

CONCLUSION

The present results indicate that (a) treatment of MAGR using MCAT in conjunction with either CM or CTG is likely to show a relapse over a period of 9 years, and (b) the outcomes obtained in maxillary areas seem to be more stable compared to the mandibular ones.

CLINICAL RELEVANCE

The mean root coverage at 12 months could not be fully maintained over 9 years. On a long-term basis, the results seem to be less stable in the mandible as compared to maxillary areas.

The branched-chain amino acid transaminase 1 sustains growth of antiestrogen-resistant and ERα-negative breast cancer

Antiestrogen-resistant and triple-negative breast tumors pose a serious clinical challenge because of limited treatment options. We assessed global gene expression changes in antiestrogen-sensitive compared with antiestrogen-resistant (two tamoxifen resistant and two fulvestrant resistant) MCF-7 breast cancer cell lines. The branched-chain amino acid transaminase 1 (BCAT1), which catalyzes the first step in the breakdown of branched-chain amino acids, was among the most upregulated transcripts in antiestrogen-resistant cells. Elevated BCAT1 expression was confirmed in relapsed tamoxifen-resistant breast tumor specimens. High intratumoral BCAT1 levels were associated with a reduced relapse-free survival in adjuvant tamoxifen-treated patients and overall survival in unselected patients. On a tissue microarray (n=1421), BCAT1 expression was detectable in 58% of unselected primary breast carcinomas and linked to a higher Ki-67 proliferation index, as well as histological grade. Interestingly, BCAT1 was predominantly expressed in estrogen receptor-α-negative/human epidermal growth factor receptor-2-positive (ERα-negative/HER-2-positive) and triple-negative breast cancers in independent patient cohorts. The inverse relationship between BCAT1 and ERα was corroborated in various breast cancer cell lines and pharmacological long-term depletion of ERα induced BCAT1 expression in vitro. Mechanistically, BCAT1 indirectly controlled expression of the cell cycle inhibitor p27^Kip1 thereby affecting pRB. Correspondingly, phenotypic analyses using a lentiviral-mediated BCAT1 short hairpin RNA knockdown revealed that BCAT1 sustains proliferation in addition to migration and invasion and that its overexpression enhanced the capacity of antiestrogen-sensitive cells to grow in the presence of antiestrogens. Importantly, silencing of BCAT1 in an orthotopic triple-negative xenograft model resulted in a massive reduction of tumor volume in vivo, supporting our findings that BCAT1 is necessary for the growth of hormone-independent breast tumors.

Volumetric difference evaluation of registered three-dimensional pre-operative and post-operative CT dental data

OBJECTIVE

The purpose of this study is to propose a complete methodology for automatically registering three-dimensional (3D) pre-operative and post-operative CT scan dental volumes as well as to provide a toolset for quantifying and evaluating their volumetric differences.

METHODS

The proposed methodology was applied to cone beam CT (CBCT) data from 20 patients in order to assess the volume of augmented bone in the alveolar region. In each case, the pre-operative and post-operative data were registered using a 3D affine-based scheme. The performance of the 3D registration algorithm was evaluated by measuring the average distance between the edges of the registered sets. The differences between the registered sets were assessed through 3D subtraction radiography. The volume of the differences was finally evaluated by defining regions of interest in each slice of the subtracted 3D data and by combining all respective slices to model the desired volume of interest. The effectiveness of the algorithm was verified by applying it to several reference standard-shaped objects with known volumes.

RESULTS

Satisfactory alignment was achieved as a low average offset of 1.483 ± 1.558 mm was recorded between the edges of the registered sets. Moreover, the estimated volumes closely matched the volumes of the reference objects used for verification, as the recorded volume differences were less than 0.4 mm(3) in all cases.

CONCLUSION

The proposed method allows for automatic registration of 3D CBCT data sets and the volumetric assessment of their differences in particular areas of interest. The proposed approach provides accurate volumetric measurements in three dimensions, requiring minimal user interaction.

Formation of human cementum following different modalities of regenerative therapy

The aim of the present study was to compare newly formed cementum following different types of regenerative therapy in humans. Eighteen patients, each displaying one advanced intrabony defect around teeth scheduled for extraction, were included in this study. The defects were treated with either guided tissue regeneration (GTR), enamel matrix protein derivative (EMD), EMD plus bioactive glass, bovine-derived xenograft (BDX), BDX plus GTR, or BDX plus EMD. After healing, the teeth were removed together with their surrounding soft and hard tissues. Cellular content, presence of artifactual splits between the new cementum and the old one or the dentin surface, and thickness of the new cementum were evaluated. Irrespective of treatment, the new cementum was of a reparative, cellular, extrinsic and intrinsic fiber type. There were no differences in cementum thickness among treatments. These findings indicate that in humans, (a) the new cementum formed after different types of regenerative therapy was, irrespective of the treatment, of a reparative, cellular, extrinsic and intrinsic fiber type, and (b) the regenerative modality does not seem to influence the type of newly formed cementum.

Healing of human intrabony defects following regenerative periodontal therapy with a bovine-derived xenograft and guided tissue regeneration

The purpose of the present study was to histologically evaluate the healing of human intrabony defects following treatment with either a bovine-derived xenograft (BDX) and guided tissue regeneration (GTR) [BDX + GTR] or a bovine-derived xenograft mixed with collagen (BDX Coll) and GTR [BDX Coll + GTR]. Eight patients with chronic periodontitis and each with one very deep intrabony defect around a tooth scheduled for extraction were treated with either a combination of BDX + GTR (five patients) or with BDX Coll + GTR (three patients). The postoperative healing was uneventful in all eight cases. After a healing period of 6 months, the teeth or roots were extracted together with some of their surrounding soft and hard tissues and subsequently fixed in 10% buffered formalin. Following decalcification in EDTA, the specimens were embedded in paraffin and 8-microm histological sections were cut in the mesio-distal direction, parallel to the long axes of the teeth. The sections were alternatively stained with hematoxylin and eosin, van Giesson's connective tissue stain or with the Ladevig's connective tissue staining method and examined under the light microscope. Generally, formation of new cementum with inserting collagen fibers was found in seven out of the eight treated cases, whereas in the remaining case (treated with BDX + GTR) the healing was characterized by formation of a long junctional epithelium along the debrided root surface and no formation of cementum or bone. In the specimens demonstrating periodontal regeneration the new cementum was always of a cellular type. In most cases, the graft particles were surrounded by bone. In some areas, the bone tissue around the graft particles was connected by perpendicularly inserting collagen fibers to the newly formed cementum on the root surface. The epithelium downgrowth stopped always at the most coronal part of the newly formed cementum. No remnants of the membrane material were observed in any of the biopsies. Connective tissue encapsulation of the graft particles was rarely observed and was limited to the most coronal part of the defects. The findings of the present study provide evidence that treatment of intrabony defects with both BDX + GTR and BDX Coll + GTR may enhance periodontal regeneration in humans.

Immunohistochemical evaluation of matrix molecules associated with wound healing following treatment with an enamel matrix protein derivative in humans

Application of enamel matrix protein derivative (EMD) onto a debrided and conditioned root surface has been shown to promote periodontal regeneration in animals and humans. However, until now there is virtually no information from humans describing the expression of different matrix molecules in the newly formed periodontal tissues following treatment with EMD. This study investigated immunohistochemically in humans the expression of matrix molecules associated with periodontal tissues reformed after treatment with EMD. Eight patients with intrabony defects were treated with EMD. Six months after surgery teeth together with some of their surrounding soft and hard tissues were removed, fixed in buffered formalin, decalcified in EDTA, and embedded in paraffin. Serial sections of 6 micro m were cut in mesiodistal direction. Sections were evaluated immunohistochemically by means of polyclonal antibodies against osteopontin, collagen I and collagen III. The original (non-treated) parts of the periodontium served as controls. In all specimens the healing resulted to a varying extent in formation of cementum, periodontal ligament and alveolar bone. In all specimens the expression of the investigated matrix molecules was stronger at the reformed than at the original sites. Osteopontin expression was most intense at the border near the newly formed cementum and bone. In the regenerated periodontal ligament, collagen I and III were localized throughout the entire periodontal ligament connective tissue. Within the newly formed PDL connective tissue the immunohistochemical staining appeared stronger for collagen III than for collagen I. The present findings suggest that (a) treatment of human intrabony defects with EMD creates an environment favourable for periodontal regeneration and, (b) in humans the healing and/or remodelling process of the reformed tissues may be followed immunohistochemically for a period of 6 months.

Treatment of intrabony defects with enamel matrix proteins and guided tissue regeneration

BACKGROUND

Utilisation of enamel matrix proteins (EMD) and application of the guided tissue regeneration principle (GTR) are treatment modalities which both have been shown to result in periodontal regeneration. However, it is yet unknown whether the combination of EMD and GTR may additionally favor the regeneration process.

AIM

The aim of the present controlled study was to evaluate clinically the treatment effect of EMD, GTR, combination of EMD and GTR, and flap surgery (control) on intrabony defects.

MATERIAL AND METHODS

56 patients each of whom displaying one intrabony defect of a depth of at least 6 mm were randomly treated with one of the treatment modalities. Prior to surgery and at one year after, the following parameters were evaluated by a blinded examiner: Plaque index (PlI), gingival index (GI), bleeding on probing (BOP), probing pocket depth (PPD), gingival recession (GR) and clinical attachment level (CAL). No statistical significant differences between the four groups were observed at baseline for any of the investigated parameters.

RESULTS

At 1 year after therapy, the sites treated with EMD demonstrated a mean PPD reduction of 4.1 +/- 1.7 mm and a mean CAL gain of 3.4 +/- 1.5 mm (p<0.001). The sites treated with GTR showed a mean PPD reduction of 4.2 +/- 1.9 mm and a mean CAL gain of 3.1 +/- 1.5 mm (p<0.001). The sites treated with the combined treatment showed a mean PPD reduction of 4.3 +/- 1.4 mm and a mean CAL gain of 3.4 +/- 1.1 mm (p<0.001). In the control group, the mean PPD reduction was 3.7 +/- 1.4 mm (p<0.001) and the mean CAL gain measured 1.7 +/- 1.5 mm (p<0.01). All 4 treatments led to statistically significant PPD reduction and CAL gain. All three regenerative treatments led to higher CAL gain than the control treatment (p<0.05). No statistical significant differences in PPD reduction and CAL gain were observed between the three regenerative treatments.

CONCLUSION

It may be concluded that (a) all 3 regenerative treatment modalities may lead to higher CAL gain than the control one, and (b) the combined treatment does not seem to improve the outcome of the regenerative procedure.

Patterns of cytokeratin expression in monkey and human periodontium following regenerative and conventional periodontal surgery

The pattern of cytokeratin expression has been extensively described in the normal and inflamed periodontium. However, there is no information regarding the pattern of cytokeratin expression in the periodontium which has been reformed following regenerative periodontal surgery. The aim of the present investigation was to evaluate the pattern of cytokeratin expression in the reformed human and monkey periodontium following regenerative and conventional periodontal surgery. In 3 monkeys, acute fenestration-type and chronic intrabony defects were treated with guided tissue regeneration (GTR), enamel matrix proteins (EMD), or coronally repositioned flap surgery (control). After a healing period of 5 months, the animals were sacrificed and perfused with 10% buffered formalin for fixation. Specimens containing the defects and surrounding tissues were dissected free, decalcified in EDTA and embedded in paraffin. Histological sections were cut with the microtome set at 3 microm. The sections were alternatively stained either with hematoxylin and eosin, or immunohistochemically by using one of the broad range monoclonal antibodies 34betaE 12 (for cytokeratins 1, 5, 10 and 14) or KL 1 (for cytokeratins 1, 2, 5, 6, 7, 8, 10, 11, 16 and 19), or one of the individual monoclonal antibodies LL025 (for cytokeratin 16), DC 10 (for cytokeratin 18), A53-B/A2 (for cytokeratin 19). Twelve patients, each displaying one deep intrabony defect scheduled for extraction due to advanced periodontitis or prosthetic reasons, were treated as described above. Following a healing period of 6 months, the teeth were extracted together with some of their surrounding soft and hard tissues. The histological and immunohistochemical processing of the human biopsies was identical to that described in monkeys. The results revealed that both the normal non-treated (original) monkey and human junctional epithelium stained strongly with all of the monoclonal antibodies used. The reformed junctional epithelium displayed the same cytokeratin expression pattern as the non-treated junctional epithelium. No differences regarding the cytokeratin expression pattern of the junctional epithelium were found between the treatments and types of healing (i.e. regenerative, through a new periodontal ligament, or reparative through a long junctional epithelium). In the intact periodontal ligament, the epithelial rests of Malassez displayed a comparable cytokeratin expression pattern to that of the junctional epithelium. However, no expression of cytokeratins was seen in the newly formed periodontal ligament. In such specimens, cytokeratin expression was observed only until the borderline between the regenerated cementum and the epithelial downgrowth. It was concluded that: a) the reformed junctional epithelium, following any type of surgical procedure, displays a similar pattern of cytokeratin expression to the original junctional epithelium; b) in the newly formed periodontal ligament, no expression of cytokeratins is present; and c) the epithelial rests of Malassez do not seem to reform after regenerative periodontal surgery.

Clinical and histologic evaluation of human intrabony defects treated with an enamel matrix protein derivative (Emdogain)

An enamel matrix protein derivative (Emdogain) has been recently shown to promote periodontal regeneration in experimentally created recession-type defects. However, only limited histologic data from human material are available concerning the healing of intrabony periodontal defects following treatment with Emdogain. The aim of the present study was therefore to present the clinical and histologic results following the application of Emdogain in intrabony defects. Two patients with marginal periodontitis and deep intrabony defects adjacent to teeth scheduled for extraction were treated with Emdogain. The postoperative healing phase was uneventful in both cases. At 6 months following treatment, newly formed cementum with inserting collagen fibers was found in both specimens. In one case, the new attachment formation was also accompanied by bone neoformation. The results of this human histologic study indicate that Emdogain possesses the potential to stimulate new connective tissue attachment formation in human intrabony defects.

GTR with three different types of membranes in the treatment of intrabony periodontal defects: three-year results in sixty consecutive cases

The aim of the present study was to evaluate the clinical results at 3 years following treating intrabony periodontal defects with different nonresorbable and bioabsorbable membrane barriers. Sixty intrabony periodontal defects were treated according to the principles of guided tissue regeneration (GTR). Twenty pockets were treated with Gore Resolut, a bioabsorbable membrane; 20 were treated with Gore-Tex, a titanium-reinforced membrane; and 20 with nonresorbable Gore-Tex membrane (all manufactured by Gore Regenerative Technologies, Flagstaff, AZ). The therapeutic results were evaluated by assessing probing pocket depth (PPD), recession of the gingival margin (GR), and clinical attachment level (CAL) at baseline, at 1 and at 3 years after therapy. The postoperative phase was uneventful in all cases. At 1 year after surgery, the results showed a mean PPD reduction from 9.42 mm to 3.35 mm (p < 0.0001) with Resolut; from 10.30 mm to 4.00 with titanium-reinforced Gore-Tex (p < 0.0001); and from 8.40 mm to 3.73 mm (p < 0.0001) with Gore-Tex membranes. The mean GR increased from 1.92 mm to 3.70 mm (p < 0.001) with Resolut; from 0.47 mm to 2.85 mm (p < 0.0001) with titanium-reinforced Gore-Tex; and from 0.73 mm to 2.15 mm (p < 0.0001) with Gore-Tex membranes. The mean CAL changed from 11.35 mm to 6.92 mm (p < 0.001) with Resolut; from 10.78 mm to 6.85 mm (p < 0.0001) with titanium-reinforced Gore-Tex; and from 9.13 mm to 5.87 mm (p < 0.0001) with Gore-Tex membranes. The clinical results at 3 years were not significantly different when compared with the 1-year results (p > 0.05). No significant differences existed between the mean changes in PPD, GR, and CAL in the three different test groups. Furthermore, one tooth scheduled for extraction for periodontal and prosthodontic reasons was treated with Resolut. Histological analysis 6 months after treatment demonstrated the neoformation of a connective tissue attachment and of new alveolar bone. This additional evidence thus proved that treatment with bioabsorbable membranes according to GTR principles delivers not only clinical improvement, but also histological periodontal regeneration.

GTR with bioresorbable membranes in the treatment of intrabony defects: a clinical and histologic study

The aim of the present study was to evaluate clinically and histologically the treatment of intrabony periodontal defects with a bioresorbable membrane barrier. Fifty-two intrabony periodontal defects were treated according to the principles of guided tissue regeneration (GTR) with a bioresorbable membrane. Results were evaluated by assessing probing pocket depth, recession of the gingival margin, and clinical attachment level at baseline and at 1 and 2 years after therapy. Bone level changes were evaluated radiographically. The postoperative phase was uneventful in all cases. There was a mean probing pocket depth reduction from 8.4 to 3.6 mm, a mean increase of gingival margin recession from 1.5 to 3.0 mm, and a mean clinical attachment level change from 9.9 to 6.5 mm. Mean attachment gain was 3.4 mm. Two teeth scheduled for extraction were also treated with the same bioresorbable membrane. The histologic analysis 6 months after treatment revealed the formation of new connective tissue attachment and new alveolar bone in both cases. Based on the histologic findings it can be concluded that the clinical improvements following GTR with this type of bioresorbable membrane may represent, at least in part, true periodontal regeneration.

Healing of human intrabony defects following treatment with enamel matrix proteins or guided tissue regeneration

The aim of the present study was to evaluate histologically in humans the healing of advanced intrabony defects following treatment with enamel matrix proteins (EMD) or guided tissue regeneration (GTR). Fourteen patients, each of them displaying 1 advanced intrabony defect around teeth scheduled for extraction were included in the study. The defects were treated randomly either with an enamel matrix protein derivative (Emdogain, BIORA AB, Malmö, Sweden) or with a bioabsorbable membrane (Resolut, Regenerative Material, W.L. Gore & Assoc., Flagstaff, Arizona, USA). At baseline the mean probing pocket depth (PPD) in the EMD group was 11.3 +/- 1.8 mm and the mean clinical attachment level (CAL) 12.1 +/- 2.0 mm, whereas in the GTR group the mean PPD was 11.4 +/- 2.2 mm and the mean CAL 13.3 +/- 2.3 mm. Healing was uneventful in all cases. Neither allergic reactions against EMD or the bioabsorbable membrane, nor suppuration or abscesses were observed. The clinical results revealed at 6 months in the EMD group a mean PPD of 5.6 +/- 1.3 mm and a mean CAL of 9.1 +/- 1.5 mm. In the GTR group the mean PPD was 5.6 +/- 1.3 mm and the mean CAL 10.1 +/- 1.5 mm. The histological analysis showed in the EMD group a mean 2.6 +/- 1.0 mm of new attachment (i.e. new cementum with inserting collagen fibers) and a mean 0.9 +/- 1.0 mm of new bone. In this group, the formation of new attachment was not always followed by bone regeneration. In the GTR group, the mean new attachment was 2.4 +/- 1.0 mm and the mean new bone 2.1 +/- 1.0 mm. In every case treated with GTR, the formation of new attachment was followed by a varying amount of new bone. After both types of regenerative treatment the newly formed cementum displayed a predominantly cellular character. The findings of the present study indicate that the treatment of intrabony defects with enamel matrix proteins or with bioabsorbable membranes enhances the formation of a new connective tissue attachment in humans.

Presence of oxytalan fibers in human regenerated periodontal ligament

The aim of the present study was to investigate whether oxytalan fibers are formed in the regenerated human periodontal ligament. 6 patients, each of them exhibiting an advanced intrabony defect, were treated with a bioresorbable membrane according to the GTR-principle. Following a healing period of 6 months, the teeth were extracted together with their surrounding soft and hard tissues and subsequently fixed in 10% buffered formalin. Following decalcification in EDTA, the specimens were embedded in paraffin and 8-microm histological sections were cut in the mesio-distal direction, parallel to the long axes of the teeth. The sections were stained with hematoxylin and eosin, or with the oxone-aldehyde-fuchsin-Halmi staining method and examined in the light microscope. A regenerated periodontal ligament containing newly-formed oxytalan fibers was observed in all specimens. Many of them inserted into the newly formed cementum on the root surface. It is concluded that oxytalan fibers are formed de novo in human regenerated periodontal ligament tissue.

[A 3-year experience with guided tissue regeneration procedures]

The Guided Tissue Regeneration (GTR) procedures are promoting a clinically and radiologically as well as histologically verifiably periodontal attachment gain. The objective of the study was to evaluate the clinical efficacy of these GTR techniques. In the past four years different barrier membranes (Gore-tex, Resolut and Guidor) were used around 318 teeth of 196 patients. 169 periodontal defects of 140 patients were followed up at least for two years. 54 patient had chronic adult type periodontitis, 67 suffered with rapidly progressing periodontitis and 15 had different severe mucogingival lesions. 111 vertical bony defects, 43 Class II-III furcation lesions and 15 mucogingival lesions were surgically corrected. The average preoperative probing depth (PD) and the clinical attachment loss (CAL) of the vertical bony defects were 5.3 +/- 1.7 mm and 6.2 +/- 1.9 mm respectively. The PD of the deepest Class III furcation lesion was 11 mm. The average gingival recession of the mucogingival lesions was 4.5 +/- 1.1 mm. The GTR technique provided the best results in the Class II-III furcation lesions, where an average 2.4 +/- 0.9 clinical attachment gain was observed one year postoperatively. The GTR techniques provided an average 1.8 +/- 1.2 mm attachment gain in the vertical bony crater cases. In both groups of cases a marked gingival recession followed the healing and the periodontal regeneration. In this way the average reduction in the probing depth exceeded the average attachment gain by more that 1.5 mm. 1 year after the operation the average radiologic bone fill was about 0.9-1.2 mm. The resorbable barrier membranes resulted in clinically significant root coverage and an average 3.5 +/- 1.7 mm gain in the width of keratinized gingiva. The success or failure of our cases were mainly determined by the patient's compliance, the level of the postoperative professional and individual oral hygiene and the number of periodontal recalls. These findings are also underlining the importance of the high standard of oral hygiene in the postoperative periodontal regeneration.

[The effect of certain stages of periodontal treatment on the regeneration of periodontal tissues]

The regenerative potential of the periodontal tissues is relatively limited. The attachment loss has long been considered as an irreversible damage of the periodontium. Most of the conventional methods of the comprehensive periodontal treatment provided no convincing evidence of true new periodontal attachment formation. Most of the surgical and nonsurgical approaches achieved either secondary gingival recession and/or long epithelial attachement. The recently introduced guided tissue regeneration techniques can make the regeneration of the fibrous periodontal attachment and convincing clinical and histological evidences of new cementum and bone formation possible, as well as the regeneration of the perpendicular Sharpey's fibers fully embedded into the matrix of the appositionally formed new cementum and bone. The theories and clinical implications of these techniques are discussed and illustrated with clinical cases.

[Possibilities of reducing the sensitivity of the neck of the tooth]

Authors overview the etiology and pathomechanism of the root hypersensitivity. The most commonly used therapeutical aids and devices are discussed. They discuss the theory of action of the drugs used for controlling root hypersensitivity. In details the dental literature of devices used on the individual bases--included different fluoride compounds, stronciumchloride, and potassium nitrate--are reviewed. In the end the authors's own clinical experience and findings with the Sensodyne toothpaste (kindly donated by the Block Drug Co.) are presented.

[Importance of periodic follow up of periodontal diseases for the maintenance of periodontal health and the longevity of dental restoration]

The major objective of the author's investigation was to determine if the progression of attachment loss, the recurrence of active phase of periodontitis and development of new carious lesions can be controlled and prevented in individuals with prior history of aggressive periodontitis provided full mouth reconstruction and maintained at a proper level of oral hygiene. The results of a group on regular periodontal recall program were compared with the five years dental and periodontal findings on a matched group of patients having not been on regular maintenance program. The well maintained group of patients' annual recall data did not vary markedly. In five years basically the same amount of attachment apparatus was maintained. The reexamination of the non recall group at the end of the fifth year shoved a total deterioration of dentition due to the progression of periodontal disease and attachment loss. Especially those of rapidly progressing periodontitis cases shoved 70 to 100% attachment loss. This comparative study attempted to outline the insufficiency of our former dental philosophy of patient management and follow up. Authors emphasize the importance of the follow up, and maintenance of a very high level.

Oligomeric states of spectrin in normal erythrocyte membranes: biochemical and electron microscopic studies

We estimated the relative amounts of oligomeric species of spectrin in 0 degrees C red-cell-membrane extracts, including those released from spectrin-actin-polypeptide 4.1 complexes after mild urea treatment. Spectrin dimers, tetramers, and medium-size oligomers were the prominent species, accounting for 5%-10%, 45%-55%, and 25%-35% of spectrin, respectively. When examined by low-angle rotary-shadowing electron microscopy, these medium-size spectrin oligomers (e.g., hexamers, octamers, decamers , dodecamers , and quadecamers ) appeared as polyskelions formed by head-to-head association of three to seven dimers. They were stable species capable of binding to, and subsequent release from, inside-out vesicles without degradation to tetramers or dimers. The data suggest that spectrin tetramers and medium-size oligomers coexist in the normal erythrocyte membrane as the primary native spectrin species.

Erythrocytes in sickle cell anemia are heterogeneous in their rheological and hemodynamic characteristics

To understand the contribution to the pathophysiology of sickle cell anemia of the different erythrocyte density types present in the blood of these patients, we have studied the viscosimetric and hemodynamic characteristics of four major classes of hemoglobin SS erythrocytes. We have isolated reticulocytes, discocytes, dense discocytes, and irreversibly sickled cells (fractions I-IV) on Percoll-Renografin density gradients. Bulk viscosity was studied in a coneplate viscosimeter and the hemodynamic studies were performed on the isolated, artificially perfused mesoappendix vasculature of the rat (Baez preparation). Bulk viscosity measurements at shear rates of 230 S-1 demonstrate that when the cells are oxygenated, fraction I (reticulocyte rich) has a higher viscosity than expected from its low intracellular hemoglobin concentration. The rest of the fractions exhibit moderate increases in bulk viscosity pari-passu with the corresponding increases in density (mean corpuscular hemoglobin concentration). When deoxygenated, all cell fractions nearly doubled their bulk viscosity and the deoxy-oxy differences remained constant. The Baez preparation renders a different picture: oxygenated fractions behave as predicted by the viscosimetric data, but, when deoxygenated, cell fractions exhibit dramatically increased peripheral resistance and the deoxy-oxy difference are directly proportional to cell density, thus, the largest increases were observed for fractions III and IV. The differences between the rheological and the hemodynamic measurements are most probably due to the different sensitivity of the two methods to the extent of intracellular polymerization. These results also demonstrate that the hitherto unrecognized fraction III cells (very dense discocytes that change shape very little on deoxygenation) are as detrimental to the microcirculation as the irreversibly sickled cell-rich fraction IV. They may, however, induce obstruction by a different mechanism. As the extent to which these fractions are populated by erythrocytes varies considerably from patient to patient, the distribution function of cell densities in each sickle cell anemia patient might have consequences for the type of pathophysiological events occurring in their microcirculation.