Stress minimization for lattice structures. Part I: Micro-structure design

Lattice structures are periodic porous bodies which are becoming popular since they are a good compromise between rigidity and weight and can be built by additive manufacturing techniques. Their optimization has recently attracted some attention, based on the homogenization method, mostly for compliance minimization. The goal of our two-part work is to extend lattice optimization to stress minimization problems two-dimensionally. The present first part is devoted to the choice of a parametrized periodicity cell that will be used for structural optimization in the second part of our work. In order to avoid stress concentration, we propose a square cell microstructure with a super-ellipsoidal hole instead of the standard rectangular hole often used for compliance minimization. This type of cell is parametrized two-dimensionally by one orientation angle, two semi-axis and a corner smoothing parameter. We first analyse their influence on the stress amplification factor by performing some numerical experiments. Second, we compute the optimal corner smoothing parameter for each possible microstructure and macroscopic stress. Then, we average (with specific weights) the optimal smoothing exponent with respect to the macroscopic stress. Finally, to validate the results, we compare our optimal super-ellipsoidal hole with the Vigdergauz microstructure which is known to be optimal for stress minimization in some special cases. This article is part of the theme issue 'Topics in mathematical design of complex materials'.

Regression of Sebaceous Carcinoma of the Eyelid after a Small Incisional Biopsy: Report of Two Cases

Purpose

To report 2 cases of regression of sebaceous carcinoma of the eyelid after a small incisional biopsy.

Methods

Clinical, imaging, and histopathological findings are presented, with a literature review on regressing ocular tumors.

Results

Our first patient was a 79-year-old man who presented with a 10-month history of progressive left upper eyelid ptosis caused by an eyelid tumor with orbital involvement and confirmed on magnetic resonance imaging. Our second patient was a 70-year-old woman who presented with ptosis with a left upper eyelid mass. Both patients underwent a small incisional biopsy of their lesion. The histopathological diagnoses in both cases were consistent with sebaceous carcinoma. Both patients refused exenteration. Follow-up clinical examination and imaging disclosed total regression of the ptosis and of the neoplasm with no sign of recurrence in both patients over a 4-year period for Case 1 and a 7-year period for Case 2.

Conclusion

Regression following incisional biopsy of basal cell, squamous cell, and Merkel cell carcinoma, including of the eyelid, is well documented. To the best of our knowledge, our 2 cases of sebaceous carcinoma are the first to be reported with total involution clinically and on imaging of the tumor following partial incisional biopsy.

Choroidal extranodal marginal zone lymphoma diagnosed by full-thickness retinochoroidal biopsy: case report and review of the literature

The case of an 89-year-old man who was referred for a painless decrease of vision in his right eye (RE) is reported. Fundus examination of the RE showed an elevated amelanotic lesion located in the posterior pole with an adjacent focal round pigmented lesion. There was also a more peripheral amelanotic lesion extending from 6 to 9 o’clock clockwise inferotemporally. Uveitis workup and imaging studies of brain and orbits were normal. A retinochoroidal biopsy was done and showed the presence of choroidal extranodal marginal zone lymphoma. The patient was treated with external beam radiotherapy. This report presents a review of the literature of all reported cases of choroidal extranodal marginal zone lymphoma.

Factors influencing dairy calf and replacement heifer mortality in France

Herd-level risk factors for dairy calf and heifer mortality in France were identified by calculating herd-level variables (including mortality risk or rate) using the National Bovine Identification Database (2005 and 2006). Eleven dairy production areas representing different livestock systems were also included. Statistical analyses were based on a probit model (mortality risk or rate=0 or >0) and a linear model (mortality risk or rate >0) corrected by the sample bias Heckman method. The same associations were reported for 2005 and 2006. The mortality risks or rates for calves and heifers were positively associated with the proportion of purchased cows or being a Milk Control Program member and negatively associated with adhering to the Good Breeding Practices charter and having an autumn calving peak. The associations between mortality and the breeds or the production areas were positive or negative, depending on the classes of animal. Mortality and having a beef herd in addition to the dairy herd were negatively associated for noncrossed birth to 2-d-old calves, noncrossed 3-d- to 1-mo-old calves, and 3-d- to 1-mo-old heifers. Having a beef herd probably provides specific know-how related to newborn and young calf management that makes it easier to attain low mortality in pure-breed dairy calves. The proportion of males born was positively associated with mortality for the birth to 2-d-old calves (all classes) and for the 3-d- to 1-mo-old beef-crossed calves, but negatively for all classes of heifers. This indicates that heifer management was improved when the availability of newborn heifers decreased, resulting in low mortality. This lower mortality is apparent for all classes of heifers present on the farm during the year when the proportion of males was low, and demonstrates an anticipatory effect. In conclusion, this study shows that the presence of a beef herd in addition to the dairy herd within a farm is associated with decreased dairy calf mortality. It also shows that heifer mortality decreases when the proportion of heifers born decreased. These determinants of dairy calf and heifer mortality are of great importance for farmer advisors, the dairy industry, and the political decision makers.

HAART and progression to high-grade anal intraepithelial neoplasia in men who have sex with men and are infected with HIV

BACKGROUND

Human immunodeficiency virus (HIV)-seropositive men who have sex with men (MSM) are at risk for anal intraepithelial neoplasia (AIN) and cancer. The goal of this study was to identify risk factors associated with high-grade AIN (AIN-2,3) in HIV-positive MSM, including the receipt of highly active antiretroviral therapy (HAART).

METHODS

A cohort study involving 247 HIV-seropositive MSM receiving HAART or initiating HAART was followed up every 6 months for 3 years with human papillomavirus (HPV) testing and high-resolution anoscopy to identify predictors of AIN-2,3 by Cox regression analysis and period prevalence logistic regression.

RESULTS

AIN-2,3 was observed during the study in 132 (53%) of 247 participants. The progression rate to AIN-2,3 from a lesser abnormality at baseline was 12.8 cases per 1000 person-months (95% confidence interval [CI], 9.8-16.5 cases per 1000 person-months). The risk of AIN-2,3 increased with age (odds ratio [OR], 3.09 [95% CI, 1.12-8.52] for men 40-49 years of age and 4.78 [95% CI, 1.29-17.73] for men >50 years of age, compared with men <40 years of age) and for men whose CD4+ cell counts were <50 cells/mm(3) before starting HAART (OR, 14.40 [95% CI, 1.45-143.58]). Men who had been receiving their current HAART regimen for >4 years had a marginally significant lower risk of AIN-2,3 after adjustment for HPV (OR, 0.28 [95% CI, 0.07-1.06]) compared with those treated for <4 years. Anal HPV type 16 (HPV16) or type 18 (HPV18) infections (OR, 14.18; [95% CI, 3.51-57.32]) and HPV16 and HPV18 co-infection (OR, 31.03 [ 95% CI, 5.68-169.60]) were strongly associated with progression to AIN-2,3.

CONCLUSION

HPV16 and HPV18 infections and a low nadir CD4+ cell count increase the risk of AIN-2,3. Receiving the same HAART regimen for >4 years may contribute some benefit against AIN-2,3.

Prevalence, clearance, and incidence of anal human papillomavirus infection in HIV-infected men: the HIPVIRG cohort study

BACKGROUND

Human immunodeficiency virus (HIV)-seropositive men who have sex with men (MSM) are at higher risk of human papillomavirus (HPV) infection. This study was conducted to better understand the natural history of type-specific HPV infection in the anus.

METHODS

A cohort study was conducted among HIV-seropositive MSM in Montreal to investigate acquisition and loss of anal HPV infection. Participants were followed up every 6 months for 3 years for risk behaviors, HIV-related parameters, and HPV testing.

RESULTS

HPV DNA was detected in 97.9% of the 247 participants at baseline (median, 5 HPV types). The most common types were HPV-16 (38.2%) and HPV-6 (35.3%). Prevalent HPV-16 infections had the lowest clearance rate (12.2 cleared episodes per 1000 person-months [95% confidence interval {CI}, 8.5-17.7]) and a mean retention time of 36 months (95% CI, 32.7-38.8). The highest incidence rates were found for HPV-16 (10.8 new cases per 1000 person-months [95% CI, 8.0-14.7]), HPV-52 (10.8 new cases per 1000 person-months [95% CI, 8.2-14.1]), and HPV-53 (9.8 new cases per 1000 person-months [95% CI, 7.4-13.0]), with cumulative incidences at 36 months of approximately 30%.

CONCLUSIONS

Multiple HPV types were common in the anal canals of HIV-seropositive MSM. Incidence and clearance rates were not similar among HPV types. Ongoing surveillance of this cohort will help our understanding of the determinants of HPV persistence and progression to lesions.

Transplantation of a tissue-engineered corneal endothelium reconstructed on a devitalized carrier in the feline model

PURPOSE

To evaluate the functional outcome of tissue-engineered corneal endothelium reconstructed on a devitalized carrier and transplanted in the living feline model.

METHODS

Eighteen healthy adult cats underwent full-thickness corneal transplantation. In 11 animals, the donor cornea was reconstructed from cultured allogeneic feline corneal endothelial cells seeded on the denuded Descemet's membrane of a devitalized human cornea. The reconstructed corneal endothelium was cultured for 2 weeks before transplantation. Five control animals received autologous (n = 1), allogeneic (n = 3), or human xenogeneic (n = 1) native cornea. Two other control animals were grafted with the devitalized carrier only (no cells). Animals were observed daily by slit lamp until euthanatization on day 7. Postmortem analysis included optical coherence tomography (OCT), alizarin red staining, histology, fluorescence microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM).

RESULTS

Nine of the 11 reconstructed corneal endothelial grafts and all five native (autologous, allogeneic, xenogeneic) control grafts were clear and thin 7 days after grafting. In contrast, the two control grafts consisting of the carrier only (without endothelium) remained thick and opaque. Alizarin red staining, histology, SEM, and TEM showed that the transplanted reconstructed endothelium maintained a normal morphology and ultrastructure and expressed the function-related proteins Na(+)/K(+)-ATPase alpha1, Na(+)/HCO(3), and ZO-1.

CONCLUSIONS

This study provides evidence for the short-term (7-day) anatomic and functional success of corneal transplantation with a tissue-engineered corneal endothelium reconstructed on a devitalized carrier.

Choroidal amelanotic melanoma in a patient with oculocutaneous albinism

CASE REPORT

We describe the clinical presentation of a choroidal amelanotic melanoma in a 46-year-old woman with oculocutaneous albinism. Clinical aspects, investigations, and management are presented, and findings from computed tomography and magnetic resonance imaging are described. Microscopic findings and histopathological features, demonstrating a spindle B-cell melanoma of the choroid, are also reviewed.

COMMENTS

Magnetic resonance imaging may be helpful in diagnosing amelanotic melanoma in patients with oculocutaneous albinism.

Diffusion-weighted MR imaging of the liver of hepatitis C patients

Magnetic resonance diffusion-weighted imaging (DWI) of the liver was investigated to determine whether this method could be used to differentiate between the stages of fibrosis and inflammation for hepatitis C viral infection. DWI data were recorded for 18 hepatitis C patients and 10 control subjects using a modified pulse sequence allowing a 52 ms echo time delay. Acquisitions were performed with breath holding using five different b gradient factor values ranging between 50 and 250 s/mm(2) and in the three axes. Apparent diffusion coefficient (ADC) values were measured from a 5.7 cm(2) area in the central region of the liver. The inflammation and fibrosis grades were evaluated histologically on a biopsy sample. The mean ADC values were 2.30 +/- 1.28 x 10(-3) and 1.79 +/- 0.25 x 10(-3) mm(2)/s for hepatitis C patients and control subjects, respectively. Using our technique, no correlation could be found between the ADC values and the inflammation or fibrosis scores, indicating that tissue changes produced by hepatitis C do not appear to be quantifiable by DWI.

Herpes simplex virus type II is not a cofactor to human papillomavirus in cancer of the uterine cervix

OBJECTIVE

Cells that were cotransfected with herpes simplex virus-16 and the herpes simplex virus type 2 Xho -2 DNA induce tumors in nude mice. In a cross-sectional study, we investigated the role of herpes simplex virus type 2 as a cofactor to human papillomavirus in cervical cancer.

STUDY DESIGN

Cervical cells that were obtained with an endocervical Cytobrush brush (Medscand) from 439 women (50 women with cancer lesions, 65 women with high-grade squamous intraepithelial lesions, 80 women with low-grade squamous intraepithelial lesions, 244 healthy subjects) and DNA that was extracted from 150 cervical cancer biopsy specimens were analyzed with polymerase chain reaction for herpes simplex virus type 2 Xho -2 and Bgl IIC transforming DNA sequences.

RESULTS

All 439 cervical samples and 150 cervical cancer biopsy specimens tested negative for herpes simplex virus type 2 Xho -2 and Bgl IIC DNA by polymerase chain reaction. Overall, none of 200 samples (0%) from women with invasive cervical cancer contained herpes simplex virus type 2 Xho -2 or Bgl IIC DNA (95% CI, 0.0-1.8).

CONCLUSION

Although herpes simplex virus type 2 Bgl IIN transforms epithelial cells in vitro, it was not detected in cervical cancer specimens.

Detection of human herpes virus type 6 DNA in precancerous lesions of the uterine cervix

Human herpes virus type 6 (HHV-6) DNA has been suggested to be a cofactor to human papillomavirus (HPV) in cervical cancer. In a cross-sectional study, we investigated the association between HHV-6 DNA detected in cervical brushings and high-grade squamous intraepithelial lesions (HSIL), while controlling for genital infection with 27 genotypes of HPV. Of the 320 women recruited from an oncologic gynecology clinic, 50 had invasive cervical cancer, 65 had HSIL, 80 had low-grade squamous intraepithelial lesions (LSIL), and 125 were normal. Four of the seven HHV-6-positive women had HSIL. HHV-6 was associated with HSIL after adjusting for age and socioeconomic status (odds ratio [OR] of 10.9, 95% confidence interval [CI]: 1.1-107.1). This association was no longer significant after controlling for HPV (OR = 6.4, 95% CI = 0.3-128.5). HHV-6 was detected in cervical samples from women with precancerous and cancerous lesions of the cervix, but not significantly more frequently than in normal women.

Bone metastasis from a granulosa cell tumor of the ovary

BACKGROUND

Granulosa cell tumors (GCT) of the ovary generally have a good prognosis. Recurrences tend to be late and are usually abdominopelvic. Bone metastases are extremely rare.

CASE

A case of recurrent GCT with vertebral metastasis is presented. Radiologic studies were helpful in documenting the presence of an invasive tumor destroying the vertebral body of T7. Bone scintigraphy excluded other metastatic sites. Diagnosis could not be established by CT-scan-directed fine-needle aspiration cytology or trocar biopsies. Since the lesion was isolated and resectable, aggressive surgery with complete tumoral excision was performed followed by local radiation therapy. Megestrol acetate was given as systemic treatment.

CONCLUSION

Multiple treatments of GCT may alter the pattern of recurrence. Every symptom should be thoroughly evaluated. Bone metastases may be treated aggressively.

Persistent hyperplastic primary vitreous with retinal tumor in tuberous sclerosis: report of a case including tumoral immunohistochemistry and cytogenetic analyses

OBJECTIVE

The authors describe an ocular lesion combining the characteristics of persistent hyperplastic primary vitreous (PHPV) and a retinal tumor in an infant with tuberous sclerosis complex (TSC).

STUDY DESIGN

Case report.

METHODS

Immunohistochemistry and cytogenetic studies were performed on TSC cells from an intraocular tumor in a 6-week-old infant.

RESULTS

Histopathologic examination showed a thick fibrovascular membrane between the aspect of the lens and the astrocytic component of the mass. Glial fibrillary acidic protein (GFAP) showed a variable intracytoplasmic reaction in the astrocytic proliferation, involving approximately 50% of the cells. Tissue culture studies showed a fairly rapid proliferation of fusiform cells, consistent with bipolar astrocytic cells. Cytogenetic studies showed one abnormal clone consisting of three hyperdiploid cells with a loss of chromosome 9 and a gain of chromosomes 6 and 12.

CONCLUSION

The atypical localization of the retinal tumor could be explained by the fact that it was trapped during its proliferation by the retinal detachment associated with the PHPV.

Human immunodeficiency virus infection is a major risk factor for detection of human papillomavirus DNA in esophageal brushings

The presence of human papillomavirus (HPV) DNA in esophageal brushings from human immunodeficiency virus (HIV)-seropositive hosts was investigated in a cross-sectional study. Oral and esophageal brushings from individuals scheduled for esophagogastroscopy (53 HIV-positive and 61 age-matched HIV-negative patients) were tested for the presence of HPV DNA by a consensus L1 polymerase chain reaction assay. HPV DNA was detected in esophageal brushings of 9 (17%) of the 53 HIV-seropositive patients and 0 of the 61 HIV-negative individuals. HPV-16 DNA was the most frequently detected. No proliferative mucosal lesion was noted in individuals with HPV-positive esophageal brushings. Cytological smears were done for 6 of the 9 patients with HPV-positive esophageal brushings, and epithelial atypia was recorded for 1. HIV infection and a history of genital herpes were strong independent predictors of HPV, suggesting that HPV is transmitted sexually in the esophagus.

Risk factors for oral human papillomavirus in adults infected and not infected with human immunodeficiency virus

BACKGROUND AND OBJECTIVES

To investigate in a cross-sectional study the determinants of oral human papillomavirus infection in 287 individuals who are sexually active.

GOAL

To assess prevalence as well as risk factors for oral human papillomavirus infection.

STUDY DESIGN

One hundred seventy-eight human immunodeficiency virus-seropositive (158 men and 20 women) and 109 human immunodeficiency virus-negative (73 men and 36 women) individuals were recruited consecutively from sexually transmitted disease-human immunodeficiency virus clinics and gastrointestinal endoscopy clinics. Oral brushings were tested with the L1 consensus polymerase chain reaction assay for human papillomavirus detection.

RESULTS

Human papillomavirus DNA was detected in 32 (11.2%) of 287 individuals. Associated with oral human papillomavirus infection on univariate analyses were human immunodeficiency virus infection (odds ratio, 6.9; 95% confidence interval, 2.0-23.2), homosexuality (odds ratio, 3.7; 95% confidence interval, 1.5-9.4), unprotected oral sex (odds ratio, 5.5; 95% confidence interval, 1.6-18.4), syphilis (odds ratio, 2.5; 95% confidence interval, 1.1-6.3), gonorrhea (odds ratio, 4.2; 95% confidence interval, 1.9-9.1), Chlamydia trachomatis (odds ratio, 4.4; 95% confidence interval, 1.8-10.6), and genital herpes (odds ratio, 2.9; 95% confidence interval, 1.3-6.5). Human immunodeficiency virus infection and C. trachomatis were independently predictive of human papillomavirus infection in multivariate stepwise logistic regression.

Liver angiomyolipoma: classic and unusual presentations

Two cases of liver angiomyolipoma (AML) are presented. The first case has the classical imaging findings previously reported. The second case has no fat content on the various imaging modalities. AML should probably be included in the differential diagnosis of any hypervascular lesion of the liver. Preoperative diagnosis with core biopsy is possible.

Toxoplasma gondii retinochoroiditis and optic neuritis in acquired immune deficiency syndrome. Report of a case

A 29-year-old man with acquired immune deficiency syndrome (AIDS) was found to have a retinochoroiditis and optic neuritis of his left eye. Results of fundus examination showed inflammatory and hemorrhagic retinal lesions consistent with retinitis due to cytomegalovirus infection. A computed tomographic (CT) scan demonstrated enlargement of the optic nerve. The eye was enucleated and results of histopathologic examination showed retinal necrosis with underlying choroiditis and an optic neuritis. Numerous encysted Toxoplasma gondii organisms were present in the retina and tachyzoites were present in the optic nerve. To the authors' knowledge this is the second histologically documented case of Toxoplasma optic neuritis in a patient with AIDS.

Hemolytic uremic syndrome in renal allografted patients treated with cyclosporin

The classical triad of hemolytic uremic syndrome (microangiopathic hemolytic anemia, severe thrombopenia, and renal failure) developed de novo in three of our renal transplanted patients under cyclosporin A treatment. The predominant morphologic findings in the grafts consisted of glomerular and arteriolar thrombosis as well as arteriolonecrosis, all features of the syndrome. In one instance, ischemic bowel disease supervened after graft removal and was associated with persistent low grade microangiopathic process. De novo hemolytic uremic syndrome has been reported in patients treated with cyclosporin A following bone marrow or liver transplantation as well as in a few renal graft recipients. This peculiar form of cyclosporin A nephrotoxicity should not be confused with acute rejection of the renal transplant.