Digestive endoscopy: relevance of negative findings

In patients with digestive complaints, endoscopy is the gold standard and is often the primary exploration. Positive findings in upper gastrointestinal endoscopy occur in 30 to 40% in relation to a benign or malignant structural disease. Negative findings occur therefore in 60 to 70% of cases: dyspepsia and/or reflux are functional diseases. Colonoscopy aims essentially at screening of colorectal cancer. Digestive cancer is very rare under 50 years, and most cases detected with symptoms are advanced; asymptomatic early and curable cancer is detected in screening. A negative finding at endoscopy is reliable in the hands of an experienced endoscopist controlling the risk of false negative and false positive findings. A reliable negative endoscopy is beneficial for the quality of life when it relieves anxiousness of the patient. It may be cost effective if drugs and consultations are decreased. Overuse of negative endoscopy is not so much through large indications, that in repetition of negative procedures. The relevance of negative endoscopy in screening for cancer in the upper and lower digestive tract, is whether is should be repeated. There is tendency to increased intervals in surveillance protocols. In the very near future the first role of endoscopy in the primary diagnosis could be challenged by concurrent techniques. Future progress is based upon a Quality Assurance program for quality, experience of the operator a control of the cost and a research programme on tolerance with a trend to reduced sedation.

Effect of dietary lipids on hepatic Na+,K(+)-ATPase in cyclosporine A-treated rats: immunocytochemical analysis of alpha1 subunit by confocal laser scanning microscopy imaging

We studied the effect of dietary soybean lecithin or triacylglycerol on hepatic Na+,K(+)-ATPase in cyclosporine A-treated rats by means of quantitative immunocytochemistry. Cyclosporine A-treated rats were fed lecithin or a triacylglycerol-enriched diet or a low-fat diet. As a control, one group was only fed the low-fat diet; the three other groups were treated with cyclosporine A solvent and received the low fat, lecithin, or triacylglycerol diet. Bile canalicular staining significantly decreased in all cyclosporine A-treated groups with the higher values in lecithin-fed rats. In basolateral membranes, no decrease was observed in the lecithin-cyclosporine group, in contrast to the other groups. The triacylglycerol-cyclosporine group had lower values in both membrane domains. The alteration of Na+,K(+)-ATPase by cyclosporine A was related to cholestasis evidenced by a decrease in bile salt secretion. These modifications were prevented by dietary soybean lecithin and amplified by dietary soybean triacylglycerol.

Outcome of pediatric Graves' disease after treatment with antithyroid medication and radioiodine

OBJECTIVE

To evaluate the efficacy of antithyroid medication in the initial treatment of pediatric Graves' disease and the frequency of use and outcome of radioiodine as second-line therapy.

DESIGN

Retrospective review.

SETTING

Tertiary care children's hospital.

PATIENTS

Thirty-three patients (29 female, 4 male; mean age 12.7 years) who started treatment for hyperthyroidism between Jan. 1, 1990, and Dec. 31, 1994.

INTERVENTIONS

Initial treatment with propylthiouracil or methimazole (with addition of levothyroxine if needed to maintain euthyroidism); subsequent treatment with radioiodine.

OUTCOME MEASURES

1) Clinical and laboratory features at the time of diagnosis; 2) doses and duration of antithyroid drug treatment and response to treatment; 3) need for treatment with levothyroxine to maintain euthyroidism during the trial of antithyroid medication; 4) indications for radioiodine therapy, and the dose and number of treatments with 131iodine (131I); 5) thyroid status at last follow-up visit (at least 2 years after diagnosis).

RESULTS

All patients were initially treated with antithyroid drugs, and levothyroxine was added in 16 subjects to maintain euthyroidism. The median duration of drug treatment was 21 months. Ultimately, 24/33 patients (73%) received radioiodine following a trial of antithyroid drugs because of a) side effects of antithyroid medication (in 3 patients); b) inadequate response to medication (in 8 patients); and c) relapse (in 13 patients), which occurred at a median of 6 (range 1 to 16) months following cessation of drug therapy. Five patients required a second dose of radioiodine and 2 patients required 3 doses. Of the 24 patients treated with radioiodine, at last follow-up after the most recent treatment (median 18.5, range 3 to 55 months), 6 patients were euthyroid, 16 required thyroxine replacement, and 2 were-still, or again, hyperthyroid.

CONCLUSION

In our population of children and adolescents, treatment of hyperthyroidism with antithyroid drugs frequently resulted in either side effects, inadequate response to medication or subsequent relapse, all of which led to radioiodine therapy. We conclude, therefore, that radioiodine could be considered as one of the first-line options in older children and adolescents with hyperthyroidism.

[Diagnosis and evaluation of the extent of cancer of the esophagus]

Oesophageal cancer includes two distinct tumours: squamous cell cancer is related to alcohol and tobacco consumption; adenocarcinoma develops on a metaplastic columnar mucosa lining the oesophagus (Barrett's oesophagus). In Western countries the ratio of the 2 tumors is 6 to 4. Dysphagia is a late symptom in the evolution and corresponds in most cases to advanced cancer with poor prognosis. Treatment decision required evaluation of the performance status, search for associated tumors (mouth, pharynx and respiratory tract), and evaluation of the locoregional extension of the primary tumour. In the absence of dysphagia, detection of oesophageal cancer at an early stage is compatible with a curative option.

A quantitative immunocytochemical study of Na+,K+-ATPase in rat hepatocytes after STZ-induced diabetes and dietary fish oil supplementation

Because diabetes causes alterations in hepatic membrane fatty acid content, these changes may affect the Na+,K+-ATPase. In this study we documented the effects of streptozotocin (STZ)-induced diabetes on hepatic Na+,K+-ATPase catalytic alpha1-subunit and evaluated whether these changes could be normalized by fish oil supplementation. Two groups of diabetic rats received fish oil or olive oil supplementation. Both groups had a respective control group. We studied the localization of catalytic alpha1-subunit on bile canalicular and basolateral membranes using immunocytochemical methods and confocal laser scanning microscopy, and the Na+, K+-ATPase activity, membrane fluidity, and fatty acid composition on isolated hepatic membranes. A decrease in the alpha1-subunit was observed with diabetes in the bile canalicular membranes, without changes in basolateral membranes. This decrease was partially prevented by dietary fish oil. Diabetes induces significant changes as documented by enzymatic Na+,K+-ATPase activity, membrane fluidity, and fatty acid content, whereas little change in these parameters was observed after a fish oil diet. In conclusion, STZ-induced diabetes appears to modify bile canalicular membrane integrity and dietary fish oil partly prevents the diabetes-induced alterations.

X-ray structure of 5-aminolevulinic acid dehydratase from Escherichia coli complexed with the inhibitor levulinic acid at 2.0 A resolution

5-Aminolevulinic acid dehydratase (ALAD), an early enzyme of the tetrapyrrole biosynthesis pathway, catalyzes the dimerization of 5-aminolevulinic acid to form the pyrrole, porphobilinogen. ALAD from Escherichia coli is shown to form a homo-octameric structure with 422 symmetry in which each subunit adopts the TIM barrel fold with a 30-residue N-terminal arm. Pairs of monomers associate with their arms wrapped around each other. Four of these dimers interact, principally via their arm regions, to form octamers in which each active site is located on the surface. The active site contains two lysine residues (195 and 247), one of which (Lys 247) forms a Schiff base link with the bound substrate analogue, levulinic acid. Of the two substrate binding sites (referred to as A and P), our analysis defines the residues forming the P-site, which is where the first ALA molecule to associate with the enzyme binds. The carboxyl group of the levulinic acid moiety forms hydrogen bonds with the side chains of Ser 273 and Tyr 312. In proximity to the levulinic acid is a zinc binding site formed by three cysteines (Cys 120, 122, and 130) and a solvent molecule. We infer that the second substrate binding site (or A-site) is located between the triple-cysteine zinc site and the bound levulinic acid moiety. Two invariant arginine residues in a loop covering the active site (Arg 205 and Arg 216) appear to be appropriately placed to bind the carboxylate of the A-site substrate. Another metal binding site, close to the active site flap, in which a putative zinc ion is coordinated by a carboxyl and five solvent molecules may account for the activating properties of magnesium ions.

Prospective evaluation of transnasal esophagogastroduodenoscopy: feasibility and study on performance and tolerance

BACKGROUND

With a pediatric endoscope, esophagogastroduodenoscopy (EGD) can be performed via a nasal route in adults. To evaluate this new procedure, we conducted a randomized comparative study of the feasibility of diagnostic transnasal EGD and assessed the factors influencing its quality and tolerance (endoscope diameter or route).

METHODS

Transnasal EGD was attempted in 100 patients to assess its feasibility. For the analysis of quality and tolerance, 150 patients were randomized as follows into 3 groups according to the route of examinations: (1) oral route with 9.8 mm diameter standard videoendoscope; (2) oral route with 6.0 mm diameter pediatric videoendoscope; (3) transnasal route with 6.0 mm diameter pediatric videoendoscope. The operator assessed the quality of examination by standard scores. Patients quantified pain intensity, nausea, and choking sensation.

RESULTS

Transnasal EGD was feasible in 82% of patients. The quality of the examination was significantly lower with pediatric endoscope. No difference was noted concerning pain intensity, but nausea and choking sensation were significantly reduced when the nasal route was used.

CONCLUSIONS

Transnasal EGD is feasible in the routine practice of diagnostic EGD. The nasal route, and not endoscope diameter (6.0 mm vs 9.8 mm diameter), is the determining factor that explains increased patient tolerance during transnasal EGD. Technical improvements in pediatric videoendoscopes are required.

Segmental myocardial contractility versus perfusion in Kawasaki disease with coronary arterial aneurysm

The impact of Kawasaki-related coronary injury on the myocardium was evaluated in 13 patients with persistent coronary aneurysm after a follow-up period of 7.92+/-3.97 years (range 1.8 to 14.3). Myocardial segmental perfusion and contractility integrity were assessed by resting and exercise echocardiography and technetium-99 (Tc-99m) sestamibi scan. Eight patients (61.5%) had giant aneurysms (> or = 8 mm) and 9 had multivessel involvement; the mean diameter of the largest aneurysm was 8.6+/-2.5 mm (range 5 to 14). During the acute phase, myocardial infarction occurred in 1 patient and coronary thrombosis in another. At the latest echocardiographic evaluation, the mean aneurysm diameter was 6.8+/-2.4 mm (range 4.5 to 12), there was persistent giant aneurysms in 5 of 8 patients, and 3 of 9 patients had multivessel involvement. Coronary angiography demonstrated stenosis in 7 of 10 patients, with multiple levels in 2. At sestamibi scan, all 13 patients had perfusion anomalies at rest, whereas only 7 had detectable hypokinesia on echocardiography. With exercise, perfusion returned to near normal in 3 patients, improved in 3, remained unchanged in 4, and worsened in 3 patients. Segmental contractility similarly deteriorated in the latter 3 patients but also in 2 patients whose perfusion scan had improved with exercise. Three patients, normal at rest, developed segmental hypokinesia during exercise. When present, the location of observed changes in contractility on stress echocardiography corresponded to that of perfusion defect. In conclusion, abnormal myocardial perfusion is present long term after complicated Kawasaki disease, the worst anomalies accompanying persistent giant aneurysms. Unfavorable perfusion response was coupled with abnormal contractility; however, enhanced perfusion with exercise correlated poorly with segmental contractility response.

Modification of Ca2+, Mg2+-ATPase and F-actin distribution in hepatocytes of cyclosporine A treated rats. Effect of soyabean lecithin and triacylglycerol

We studied the effect of cyclosporine A on hepatic Ca2+, Mg2+-ATPase and F-actin on bile canalicular and basolateral membranes in rats fed either soyabean lecithin, or triacylglycerol enriched diet, or low fat diet. Ca2+, Mg2+-ATPase histochemical activity was not modified in lecithin-cyclosporine A group, whereas the activity was decreased in the other groups. The triacylglycerol-cyclosporine A group had the lower activity. The histochemical staining of F-actin was quite normal in lecithin-cyclosporine group but decreased in the other cyclosporine A treated groups. The lower staining was observed in the triacylglycerol-cyclosporine group. The alteration of Ca2+, Mg2+-ATPase and F-actin by cyclosporine A, related to cholestasis evidenced by a decrease in bile salt secretion, were prevented by dietary soyabean lecithin and amplified by dietary soyabean triacylglycerol.

The captopril renogram: a new tool for diagnosing and predicting obstruction in childhood hydronephrosis

PURPOSE

We evaluated the difference in response patterns of captopril versus standard renography for assessing hydronephrosis due to suspected ureteropelvic and ureterovesical junction obstruction. This technique may identify hydronephrotic kidneys in which normal function is maintained by vasoactive compensatory mechanisms. Sustained obstruction may cause these mechanisms to fail, and expose the kidneys to permanent functional deterioration in the long term.

MATERIAL AND METHODS

We prospectively studied 15 boys and 8 girls with a mean age of 3.5 years with grades III to IV/IV hydronephrosis. Evaluations included renal sonography, standard diuretic and captopril renography, glomerular filtration rate, voiding cystography, serum creatinine, blood pressure, and urinalysis with culture and sensitivity. Obstruction was suspected at the ureteropelvic junction in 19 kidneys and at the ureterovesical junction in 9. We compared differential function values obtained by standard diuretic and captopril renography.

RESULTS

We observed certain patterns in response to captopril renography, including pattern 1--unilateral decrease in hydronephrotic kidney relative function in 5 of 23 cases, 2--bilateral decreased function in 2, 3--bilateral increased function in 4 and 4--no change in function in 12 on standard renography. When half-time was more than 20 minutes on standard diuretic renography in 8 cases, captopril renography showed an ipsilateral decrease and bilateral increase in glomerular filtration rate in 4 and 1, respectively, and no change in 3. In 12 of the 23 patients (52%) there was no difference in the results of captopril and diuretic renography as well as no change in differential function on standard diuretic renography during 1 1/2 years of observation. Surgical correction was performed in 4 patients in whom half-time was greater than 20 minutes and differential function was decreased on captopril renography.

CONCLUSIONS

Our preliminary study reveals that there may be a role for captopril renography for detecting renin-angiotensin system mediated compensatory mechanisms in obstructive uropathy. When such compensatory mechanisms are activated, they may be unmasked by captopril, producing 1 of 4 patterns on renography and glomerular filtration rate. Patterns may indicate different degrees of impending renal function impairment and, thus, they may become useful for determining the progression of injury, when present, and the appropriate timing of surgical intervention.

An overview of the management of cancer of the esophagus

The surgical treatment of esophageal cancer concerns a small percentage of patients with small Stage I or II tumors and a good performance status. Nonsurgical management with concurrent radiation and chemotherapy concerns a larger group of patients, and complete tumor responses have been observed at a significant rate. This applies to inoperable patients and to operable patients when there is a relative contraindication or when large malignant lymph nodes are detected at the preoperative stage. Endoscopic palliation in monotherapy should be restricted to the smallest possible number of patients.

Cisapride 20 mg b.i.d. provides symptomatic relief of heartburn and related symptoms of chronic mild to moderate gastroesophageal reflux disease. CIS-USA-52 Investigator Group

OBJECTIVE

We evaluated the efficacy and safety of a twice-daily dosage regimen of cisapride 20 mg in relieving the symptoms of mild-moderate gastroesophageal reflux disease (GERD) in patients with moderate intensity heartburn and no history of erosive esophagitis.

METHODS

After a 2-wk, single-blind, placebo run-in period, 398 patients who continued to experience moderate intensity heartburn were randomized to either placebo (n = 196) or cisapride 20 mg (n = 202) twice daily for 4 wk.

RESULTS

Compared with placebo, cisapride significantly reduced scores for daytime and nighttime heartburn (p < 0.001), total regurgitation (p < 0.001), eructation (p = 0.04), and early satiety (p = 0.04). Cisapride 20 mg b.i.d. was also superior to placebo in reducing total use of rescue antacid medication (p < 0.001); reducing, in concordance analyses, daytime and nighttime heartburn with antacid usage (p < 0.001); increasing the percentage of heartburn-free days and antacid-free nights (p < 0.5); and increasing the percentage of patients self-rated as having minimal or better symptomatic improvement (p = 0.01). Cisapride 20 mg b.i.d. was well tolerated. The most common adverse event in the cisapride group was diarrhea, reported by 10% of patients, compared with an incidence of 4% in the placebo group.

CONCLUSION

Cisapride 20 mg b.i.d. was shown to be effective and safe for the short-term treatment of daytime and nighttime heartburn and for other symptoms associated with mild-moderate GERD.

Metastatic axillary lymph node technetium-99m-MIBI imaging in primary breast cancer

Technetium-99m-MIBI scintimammography has been shown to be useful in the detection of primary breast cancer. The purpose of this study was to evaluate the potential role of scintimammography in detecting axillary lymph node involvement in patients undergoing scintimammography to detect primary breast cancer.

METHODS

A group of 100 women with breast cancer who were scheduled for a Level I-II axillary dissection were prospectively studied. Scintimammography was performed in all patients before histopathologic confirmation of breast cancer. Two lateral (prone imaging) views and one anterior (supine) planar thoracic view were obtained 10-15 min after the injection of 25-30 mCi 99mTc-MIBI (10 min/view) by using a special breast positioning device (foam cushion) placed over the imaging table. Both of the axilla were included in the field-of-view. Two experienced blinded observers reviewed all cases both from films and from the computer screen with contrast adjustment when needed. The site of intravenous injection of 99mTc-MIBI was known to the interpreters in order to avoid reading any false-positive uptake in the axilla ipsilateral to the injection site.

RESULTS

A total of 52 patients had no axillary lymph node involvement (611 negative nodes) while 48 patients had at least one axillary lymph node with metastatic involvement (180/502 positive nodes). The sensitivity of scintimammography in detecting metastatic axillary lymph node involvement was 79.2% (38/48), and the specificity was 84.6% (44/52). The positive and the negative predictive values were 82.6% (38/46) and 81.5% (44/54), respectively.

CONCLUSION

This study shows that scintimammography has good diagnostic accuracy for detecting axillary lymph node involvement in patients with breast cancer. This information should be added to the result of standard scintimammography, which requires very minor modifications in order to simultaneously evaluate both of the axilla.

X-ray structure of 5-aminolaevulinate dehydratase, a hybrid aldolase

5-Aminolaevulinate dehydratase (ALAD) is a homo-octameric metallo-enzyme that catalyses the formation of porphobilinogen from 5-aminolaevulinic acid. The structure of the yeast enzyme has been solved to 2.3 A resolution, revealing that each subunit adopts a TIM barrel fold with a 39 residue N-terminal arm. Pairs of monomers wrap their arms around each other to form compact dimers and these associate to form a 422 symmetric octamer. All eight active sites are on the surface of the octamer and possess two lysine residues (210 and 263), one of which, Lys 263, forms a Schiff base link to the substrate. The two lysine side chains are close to two zinc binding sites one of which is formed by three cysteine residues (133, 135 and 143) while the other involves Cys 234 and His 142. ALAD has features at its active site that are common to both metallo- and Schiff base-aldolases and therefore represents an intriguing combination of both classes of enzyme. Lead ions, which inhibit ALAD potently, replace the zinc bound to the enzyme's unique triple-cysteine site.

CD4+ T-cell testing practices as implications for training

As new diseases and new testing methods emerge, clinical laboratories are faced with updating the skills of their personnel. Complex techniques, such as flow cytometry, require both education and experience to achieve a high level of proficiency. One of the ways to determine areas in which training is needed is to assess laboratory practices and compare them with practices recommended in guidelines or by panels of experts. In this paper we describe practices reported in a written survey of 206 laboratories that perform CD4+ T-cell counts (CD4). We provided a list of alternate practices for each of the key steps in the testing process and asked participants to select the practices they use in their laboratories. Published guidelines and interviews with knowledgeable "key informants" and focus groups of people who perform CD4 testing were used to formulate the questions. We interpreted variations from recommended practices as indicators of training needs. Other factors that can affect performance, such as workload, supervision, and resources, were satisfactory to the respondents. A response rate of 73% (247 of 337 laboratories) revealed that laboratories followed most of the recommended practices. Notable exceptions included some areas of quality control and quality assurance and safety. This paper also describes flow cytometry testing as it was practiced in 1993 shortly after release of some of the testing guidelines and provides a baseline of practices for that time frame.

Review article: current practice and future perspectives in the management of gastro-oesophageal reflux disease

Gastro-oesophageal reflux disease (GERD) is primarily due to incompetence of the lower oesophageal sphincter (LOS) and crural diaphragm, with transient LOS relaxation frequently accounting for daytime reflux. In the absence of drugs that adequately correct the motility defects of GERD, treatment is directed towards decreasing gastric acidity. Oesophageal healing is related to control of 24-h intragastric acidity, the degree of acid suppression and duration of treatment. H2-receptor antagonists are generally less effective in GERD than in peptic ulcer disease. While providing symptomatic relief in non-erosive GERD, they are often ineffective in healing erosive oesophagitis. Proton pump inhibitors provide more rapid and complete healing and symptom resolution. They are superior to H2-receptor antagonists in the long-term management of erosive oesophagitis and in reducing recurrence of oesophageal stricture following mechanical dilatation. In Barrett's oesophagus, high-dose proton pump inhibitors in combination with laser/photodynamic ablation therapy can produce metaplastic regression, although this does not preclude future emergence of adenocarcinoma. Surgical morbidity and mortality rates in GERD generally remain higher than those associated with long-term pharmacotherapy. However, direct comparisons between laparascopic anti-reflux surgery and proton pump inhibitor maintenance therapy remain to be performed. Although there is no evidence that H. pylori infection worsens the severity of oesophagitis or that H. pylori is carcinogenic in the metaplastic oesophageal mucosa. It has been suggested that H. pylori-positive patients requiring long-term proton pump inhibitor therapy receive bacterial eradication therapy to reduce the risk of developing atrophic gastritis.

Crystallization of 5-aminolaevulinic acid dehydratase from Escherichia coli and Saccharomyces cerevisiae and preliminary X-ray characterization of the crystals

5-Aminolaevulinic acid dehydratase (ALAD) catalyzes the formation of porphobilinogen from two molecules of 5-aminolaevulinic acid. Both Escherichia coli and Saccharomyces cerevisiae ALADs are homo-octameric enzymes which depend on Zn2+ for catalytic activity and are potently inhibited by lead ions. The E. coli enzyme crystallized in space group I422 (unit cell dimensions a = b = 130.7 A, c = 142.4 A). The best crystals were obtained in the presence of the covalently bound inhibitor laevulinic acid. The yeast enzyme (expressed in E. coli) crystallized in the same space group (I422) but with a smaller unit cell volume (a = b = 103.7 A, c = 167.7 A). High resolution synchrotron data sets were obtained from both E. coli and yeast ALAD crystals by cryocooling to 100 K.

Analysis by confocal laser scanning microscopy imaging of undilated bile canaliculi F-actin staining in the hepatocytes of human extrahepatic cholestatic liver

Many studies have demonstrated the role of bile canalicular microfilaments in bile secretion and bile flow. It is now admitted that modification of bile canalicular network of microfilaments play a role in dysfunction of bile secretion observed in many cases of cholestasis. This work intends to study F-actin, a major component of microfilaments, in human hepatocytes in extrahepatic cholestasis. Normal and extrahepatic cholestatic liver were studied. F-actin was stained with fluorescent phallotoxin and quantified by using confocal laser scanning microscopy and an image analysis method. Mean specific fluorescence (MSF) of bile canaliculi was measured. Since dilated and bile plugged canaliculi were rarely observed in cholestatic liver sections, only undilated bile canaliculi were analysed. Bile canalicular MSF was significantly increased (p < 0.05) in cholestatic hepatocytes (1.3 to 1.7 fold higher than in controls). These data demonstrate a pericanalicular thickening of F-actin microfilaments in human extrahepatic cholestatis, similar to that described in literature in many cases of human intrahepatic and extrahepatic cholestasis cases as well as in experimentally induced cholestasis. However, further studies are needed to understand this increase in F-actin pericanalicular microfilaments in human extrahepatic cholestasis.

Coating of titanium alloy with soluble laminin-5 promotes cell attachment and hemidesmosome assembly in gingival epithelial cells: potential application to dental implants

The formation of a biological seal around the transmucosal portion of dental implants may be crucial for the long-term success of these therapies. Data to date suggest that the gingival epithelium attaches to dental implants through the formation of hemidesmosomes. Biochemical and genetic data indicate that the laminin isoform, laminin-5, a component of basement membranes, plays a crucial role in the assembly and maintenance of hemidesmosomes. We report the use of soluble laminin-5 as a biological coating of titanium-alloy to promote cell attachment of the gingival epithelial cell line, IHGK. Monoclonal antibodies reactive with laminin-5 depleted the coating solution of all cell attachment activity and blocked cell attachment to laminin-5-coated disks. Immunodepletion with antibodies to fibronectin had no effect. Finally, we demonstrate that IHGK cells assembled hemidesmosomes within 24 h of attachment to laminin-5-coated titanium alloy but not to the titanium alloy alone. These results suggest that soluble laminin-5 may have clinical applications as a dental implant coating to promote the formation of a biological seal.

Effect of cementless acetabular cup geometry on strain distribution and press-fit stability

Use of cementless acetabular cups, which are slightly larger than the reamed acetabulum, can provide press-fit stability without screws; however, the ideal cup geometry to maximize stability is not clear. Acetabular strain distribution, deformation, and implant stability were studied using an axisymmetric finite-element model, and mechanical stability was assessed by testing lever-out and extraction forces required to displace different cup geometries from foam bones. The implants tested included four nonhemispheric cup geometries and 1- and 2-mm oversized hemispheric geometries. A nonhemispheric cup that provides a gradual transition from a hemisphere at the dome to a larger peripheral dimension appears to maximize peripheral strains and implant stability without increasing overall acetabular deformation as much as a larger oversized hemispheric cup.