Steffen Heegaard

Radiocarbon Dating of the Human Eye Lens Crystallines Reveal Proteins without Carbon Turnover throughout Life

Background Lens crystallines are special proteins in the eye lens. Because the epithelial basement membrane (lens capsule) completely encloses the lens, desquamation of aging cells is impossible, and due to the complete absence of blood vessels or transport of metabolites in this area, there is no subsequent remodelling of these fibers, nor removal of degraded lens fibers. Human tissue ultimately derives its 14C content from the atmospheric carbon dioxide. The 14C content of the lens proteins thus reflects the atmospheric content of 14C when the lens crystallines were formed. Precise radiocarbon dating is made possible by comparing the 14C content of the lens crystallines to the so-called bomb pulse, i.e. a plot of the atmospheric 14C content since the Second World War, when there was a significant increase due to nuclear-bomb testing. Since the change in concentration is significant even on a yearly basis this allows very accurate dating. Methodology/Principal Findings Our results allow us to conclude that the crystalline formation in the lens nucleus almost entirely takes place around the time of birth, with a very small, and decreasing, continuous formation throughout life. The close relationship may be further expressed as a mathematical model, which takes into account the timing of the crystalline formation. Conclusions/Significance Such a life-long permanence of human tissue has hitherto only been described for dental enamel. In confront to dental enamel it must be held in mind that the eye lens is a soft structure, subjected to almost continuous deformation, due to lens accommodation, yet its most important constituent, the lens crystalline, is never subject to turnover or remodelling once formed. The determination of the 14C content of various tissues may be used to assess turnover rates and degree of substitution (for example for brain cell DNA). Potential targets may be nervous tissues in terms of senile or pre-senile degradation, as well as other highly specialised structures of the eyes. The precision with which the year of birth may be calculated points to forensic uses of this technique.

Melanopsin retinal ganglion cells are resistant to neurodegeneration in mitochondrial optic neuropathies

Mitochondrial optic neuropathies, that is, Leber hereditary optic neuropathy and dominant optic atrophy, selectively affect retinal ganglion cells, causing visual loss with relatively preserved pupillary light reflex. The mammalian eye contains a light detection system based on a subset of retinal ganglion cells containing the photopigment melanopsin. These cells give origin to the retinohypothalamic tract and support the non-image-forming visual functions of the eye, which include the photoentrainment of circadian rhythms, light-induced suppression of melatonin secretion and pupillary light reflex. We studied the integrity of the retinohypothalamic tract in five patients with Leber hereditary optic neuropathy, in four with dominant optic atrophy and in nine controls by testing the light-induced suppression of nocturnal melatonin secretion. This response was maintained in optic neuropathy subjects as in controls, indicating that the retinohypothalamic tract is sufficiently preserved to drive light information detected by melanopsin retinal ganglion cells. We then investigated the histology of post-mortem eyes from two patients with Leber hereditary optic neuropathy and one case with dominant optic atrophy, compared with three age-matched controls. On these retinas, melanopsin retinal ganglion cells were characterized by immunohistochemistry and their number and distribution evaluated by a new protocol. In control retinas, we show that melanopsin retinal ganglion cells are lost with age and are more represented in the parafoveal region. In patients, we demonstrate a relative sparing of these cells compared with the massive loss of total retinal ganglion cells, even in the most affected areas of the retina. Our results demonstrate that melanopsin retinal ganglion cells resist neurodegeneration due to mitochondrial dysfunction and maintain non-image-forming functions of the eye in these visually impaired patients. We also show that in normal human retinas, these cells are more concentrated around the fovea and are lost with ageing. The current results provide a plausible explanation for the preservation of pupillary light reaction despite profound visual loss in patients with mitochondrial optic neuropathy, revealing the robustness of melanopsin retinal ganglion cells to a metabolic insult and opening the question of mechanisms that might protect these cells.

A cryptic BAP1 splice mutation in a family with uveal and cutaneous melanoma, and paraganglioma

Inactivating germ line BRCA1‐associated protein‐1 (BAP1) mutations have recently been reported in families with uveal or cutaneous malignant melanoma (UMM, CMM), mesothelioma, and meningioma. Although apparently predisposing to a wide range of tumors, the exact tumor spectrum associated with germ line BAP1 mutations has yet to be established. Here, we report a novel germ line BAP1 splice mutation, c.1708C>G (p.Leu570fs*40), in a multiple‐case Danish UMM family with a spectrum of other tumors. Whole‐exome sequencing identified an apparent missense mutation of BAP1 in UMM, CMM, as well as paraganglioma, breast cancer, and suspected mesothelioma cases in the family. Bioinformatic analysis and splicing assays demonstrated that this mutation creates a strong cryptic splice donor, resulting in aberrant splicing and a truncating frameshift of the BAP1 transcript. Somatic loss of the wild‐type allele was also confirmed in the UMM and paraganglioma tumors. Our findings further support BAP1 as a melanoma susceptibility gene and extend the potential predisposition spectrum to paraganglioma.

Primary lymphoma of the lacrimal sac: an EORTC ophthalmic oncology task force study

Aim: To define the clinical and histopathological characteristics of primary lacrimal sac lymphoma in a predominantly white population. Methods: Specimens of lacrimal sac lymphoma and follow up data were solicited from members of the Ophthalmic Oncology Task Force of the European Organization for Research and Treatment of Cancer (EORTC) and the European Ophthalmic Pathology Society (EOPS). Specimens were stained with haematoxylin and eosin and an immunohistochemical panel against leucocyte antigens was applied. Diagnosis was reached by consensus of five experienced pathologists according to the World Health Organization classification system. The histopathological findings were correlated with the clinical data. Results: Of 15 primary lacrimal sac lymphomas, five (33%) were diffuse large B cell lymphoma (DLBCL), five (33%) were extranodal marginal zone B cell lymphoma of mucosa associated lymphoid tissue (MALT lymphoma), three were classified as “transitional MALT lymphoma,” being in transition from MALT lymphoma to DLBCL, and two were unclassified B cell lymphomas. Nine of the patients were female, and the median age at the time of diagnosis was 71 years (range 45–95 years). The most frequent presenting symptoms were epiphora (85%), swelling in the region of the lacrimal sac (79%), and dacryocystitis (21%). All but one patient presented in stage I. Systemic spread occurred in three of nine patients (33%). The 5 year overall survival was 65%. Conclusions: DLBCL and MALT lymphoma are equally common in the lacrimal sac in contrast with the remaining periorbital and/or orbital region where MALT lymphoma predominates.

A recurrent germline BAP1 mutation and extension of the BAP1 tumor predisposition spectrum to include basal cell carcinoma

We report four previously undescribed families with germline BRCA1‐associated protein‐1 gene (BAP1) mutations and expand the clinical phenotype of this tumor syndrome. The tumor spectrum in these families is predominantly uveal malignant melanoma (UMM), cutaneous malignant melanoma (CMM) and mesothelioma, as previously reported for germline BAP1 mutations. However, mutation carriers from three new families, and one previously reported family, developed basal cell carcinoma (BCC), thus suggesting inclusion of BCC in the phenotypic spectrum of the BAP1 tumor syndrome. This notion is supported by the finding of loss of BAP1 protein expression by immunochemistry in two BCCs from individuals with germline BAP1 mutations and no loss of BAP1 staining in 53 of sporadic BCCs consistent with somatic mutations and loss of heterozygosity of the gene in the BCCs occurring in mutation carriers. Lastly, we identify the first reported recurrent mutation in BAP1 (p.R60X), which occurred in three families from two different continents. In two of the families, the mutation was inherited from a common founder but it arose independently in the third family.

Deep sequencing of uveal melanoma identifies a recurrent mutation in PLCB4.

Next generation sequencing of uveal melanoma (UM) samples has identified a number of recurrent oncogenic or loss-of-function mutations in key driver genes including: GNAQ, GNA11, EIF1AX, SF3B1 and BAP1. To search for additional driver mutations in this tumor type we carried out whole-genome or whole-exome sequencing of 28 tumors or primary cell lines. These samples have a low mutation burden, with a mean of 10.6 protein changing mutations per sample (range 0 to 53). As expected for these sun-shielded melanomas the mutation spectrum was not consistent with an ultraviolet radiation signature, instead, a BRCA mutation signature predominated. In addition to mutations in the known UM driver genes, we found a recurrent mutation in PLCB4 (c.G1888T, p.D630Y, NM_000933), which was validated using Sanger sequencing. The identical mutation was also found in published UM sequence data (1 of 56 tumors), supporting its role as a novel driver mutation in UM. PLCB4 p.D630Y mutations are mutually exclusive with mutations in GNA11 and GNAQ, consistent with PLCB4 being the canonical downstream target of the former gene products. Taken together these data suggest that the PLCB4 hotspot mutation is similarly a gain-of-function mutation leading to activation of the same signaling pathway, promoting UM tumorigenesis.

Human papillomavirus in normal conjunctival tissue and in conjunctival papilloma. Types and frequencies in a large series.

Aim: To examine conjunctival papilloma and normal conjunctival tissue for the presence of human papillomavirus (HPV). Methods: Archival paraffin wax-embedded tissue from 165 conjunctival papillomas and from 20 histological normal conjunctival biopsy specimens was analysed for the presence of HPV by PCR. Specimens considered HPV positive using consensus primers, but with a negative or uncertain PCR result using type-specific HPV probes, were analysed with DNA sequencing. Results: HPV was present in 86 of 106 (81%) β-globin-positive papillomas. HPV type 6 was positive in 80 cases, HPV type 11 was identified in 5 cases and HPV type 45 was present in a single papilloma. All the 20 normal conjunctival biopsy specimens were β-globin positive and HPV negative. Conclusion: There is a strong association between HPV and conjunctival papilloma. The study presents the largest material of conjunctival papilloma investigated for HPV and the first investigation of HPV in normal conjunctival tissue. HPV types 6 and 11 are the most common HPV types in conjunctival papilloma. This also is the first report of HPV type 45 in conjunctival papilloma.

Increasing incidence of ophthalmic lymphoma in Denmark from 1980 to 2005

PURPOSE To evaluate patient characteristics and incidence of ophthalmic lymphoma in Denmark during the period 1980 to 2005. METHODS All patients in Denmark with a diagnosis of ophthalmic lymphoma during the period 1980 to 2005 were retrieved from three different population-based registries. Specimens from all patients were collected and reclassified according to the World Health Organization (WHO) classification system. Incidence rates were calculated by using Poisson regression models. RESULTS A total of 228 patients with a histologically verified diagnosis of ophthalmic lymphoma were included. There was an equal distribution of males and females. The most frequent lymphoma subtype was extranodal marginal zone B-cell lymphoma (MALT [mucosa-associated lymphoid tissue] lymphoma, 55.5%) and most cases were located in the orbit (56.8%). High-grade lymphoma subtypes were found more frequently in males than in females. Incidence rates were highly dependent on the patients age. For all ages, a statistically significant annual average increase of 3.4% during the 26-year period was found. This increase was primarily due to a rise in the incidence of MALT lymphoma. CONCLUSIONS In the Danish population ophthalmic lymphoma consists primarily of orbital MALT lymphoma. Although it is a rare disease in mostly elderly patients, the incidence of ophthalmic lymphoma is increasing at a rapid pace.

Structure and composition of the inner limiting membrane of the retina. SEM on frozen resin-cracked and enzyme-digested retinas of Macaca mulatta.

After a historical introduction describing previous observations and views on the structure and composition of the internal limiting membrane of the retina (MLI), it is concluded that no definite unifying concept exists concerning the MLI structure. The authors applied frozen resin cracking with hexamethyldisilazane (HMDS) desiccation on normal and enzyme-digested specimens of monkey retinas. Distinct differences were observed between equatorial, macular, and optic disc regions. The MLI in the equatorial and disc regions was about 70 nm thick with an outer dense, basement membranelike part and an inner, loose fibrillar meshwork fusing with the vitreous fibers. The foveal region was 400 nm thick; the dense outer layer was thicker than normal basement membrane, whereas the inner loose meshwork had only a few fibrils. The enzyme-digestion experiments showed that the fibrillar meshwork consisted mainly of collagen fibers surrounded by predominantly hyaluronic acid.

Mantle cell lymphoma in the orbital and adnexal region

Aims: To characterise clinicopathological features of mantle cell lymphoma (MCL) in the orbital and adnexal region. Methods: Data on lymphoid lesions were retrieved searching the Danish Ocular Lymphoma Database 1980–2005. Specimens were collected from Danish pathological departments and re-evaluated with a panel of monoclonal antibodies. For all patients with confirmed MCL the complete clinical files were collected and reviewed. Results: Twenty-one patients with MCL in the orbital and adnexal region were identified comprising 9% (21/230) of all lymphoma in the ocular region. There were 18 male patients and three female patients with an age range from 60 to 90 years (median 75 years). Orbital and adnexal region MCL as first presenting symptom comprised 67% of the patients. Of these, 71% had bilateral involvement. The orbit (71%) and eyelids (64%) were the most commonly affected sites. All but two presented in stage III/IV. Secondary MCL comprised 33% of the patients. Bilateral affection (29%) was less common in this patient group. The median survival was not different between the two presentation groups. Patients receiving anti-CD20 (rituximab)-containing chemotherapy had a significantly better 5-year overall survival (OS) rate (83%) than patients in treatment regimes without rituximab (5-year OS rate, 8%). Conclusions: Orbital and adnexal region MCL presents in elderly males. The orbit and eyelid are frequently involved. There is a very high proportion of systemic involvement in general with MCL of the orbital and adnexal region. Most patients presented with stage IV disease and had multiple relapses and short survival time. Treatment with rituximab-containing chemotherapy improved survival significantly compared with combination chemotherapy without rituximab.