The Complete Sequence and Comparative Analysis of Ape Sex Chromosomes

Apes possess two sex chromosomes-the male-specific Y and the X shared by males and females. The Y chromosome is crucial for male reproduction, with deletions linked to infertility. The X chromosome carries genes vital for reproduction and cognition. Variation in mating patterns and brain function among great apes suggests corresponding differences in their sex chromosome structure and evolution. However, due to their highly repetitive nature and incomplete reference assemblies, ape sex chromosomes have been challenging to study. Here, using the state-of-the-art experimental and computational methods developed for the telomere-to-telomere (T2T) human genome, we produced gapless, complete assemblies of the X and Y chromosomes for five great apes (chimpanzee, bonobo, gorilla, Bornean and Sumatran orangutans) and a lesser ape, the siamang gibbon. These assemblies completely resolved ampliconic, palindromic, and satellite sequences, including the entire centromeres, allowing us to untangle the intricacies of ape sex chromosome evolution. We found that, compared to the X, ape Y chromosomes vary greatly in size and have low alignability and high levels of structural rearrangements. This divergence on the Y arises from the accumulation of lineage-specific ampliconic regions and palindromes (which are shared more broadly among species on the X) and from the abundance of transposable elements and satellites (which have a lower representation on the X). Our analysis of Y chromosome genes revealed lineage-specific expansions of multi-copy gene families and signatures of purifying selection. In summary, the Y exhibits dynamic evolution, while the X is more stable. Finally, mapping short-read sequencing data from >100 great ape individuals revealed the patterns of diversity and selection on their sex chromosomes, demonstrating the utility of these reference assemblies for studies of great ape evolution. These complete sex chromosome assemblies are expected to further inform conservation genetics of nonhuman apes, all of which are endangered species.

The transcaruncular approach in repair of orbital fractures: a retrospective study

The use of a transcaruncular approach to the medial orbit provides excellent exposure of the medial wall and avoids a cutaneous scar. This article presents the clinical procedure in a retrospective study of 8 patients. An incision through the caruncle, combined with an incision along the inferior conjunctival fornix, provides wide exposure of the medial and inferior orbit. Traumatic fractures of the orbit typically involve the thin bone of the medial and inferior walls. The clinical history and findings in 8 patients with bony orbital fractures are presented. In each case, surgical repair was based on the transcaruncular approach. Results of postoperative evaluation (range of 24 days to 32.5 months) are described, with a mean follow-up period of 8.5 months. The authors conclude that the transcaruncular approach is well suited to surgical repair of blow-out fractures to the medial orbit, in combination with an inferior transconjunctival incision.

Criteria for nonsurgical management of subperiosteal abscess of the orbit: analysis of outcomes 1988-1998

PURPOSE

On the basis of bacteriologic studies, we have recommended expectant observation with intravenous antibiotics for subperiosteal abscess (SPA) of the orbit in patients less than 9 years of age, given the absence of eight other specific surgical criteria. We attempted to test these recommendations with a prospective study.

STUDY DESIGN

Prospective noncomparative case series.

PARTICIPANTS

Forty patients younger than 9 years of age treated for orbital SPAs at the Childrens Hospital of Wisconsin from 1988 to 1998.

METHODS

Specific management criteria were applied to a cohort of 37 orbital SPA patients. Three other orbital SPA patients under the age of 9, either ineligible for medical therapy or treated outside our guidelines, were also studied. Clinical data for all patients were reviewed and analyzed.

MAIN OUTCOME MEASURES

Clinical resolution of the abscess, as evidenced by normal visual acuity, pupillary examination, motility, and globe position on the affected side.

RESULTS

Eight patients met criteria for surgical treatment and underwent prompt drainage. Of the 29 patients for whom initial nonsurgical management was recommended, 27 (93.1%) SPAs cleared with expectant observation on intravenous antibiotics, and 2 patients defaulted to surgical intervention. All cases had successful clinical outcomes.

CONCLUSIONS

In patients less than 9 years of age, orbital SPAs are likely to resolve without surgery, provided certain surgical criteria are absent.

Correlation of preoperative computed tomography and postoperative ocular motility in orbital blowout fractures

PURPOSE

To determine a relationship between preoperative soft tissue disruption and postoperative ocular motility in orbital blowout fractures.

METHODS

This retrospective cohort study reviewed 30 patients who met all criteria: retrievable coronal computed tomography (CT) scans; internal fractures of the orbital floor, with or without medial wall extension; preoperative diplopia; repair by a single surgeon; complete release of entrapped tissues; and postoperative binocular visual fields (BVFs). Motility outcomes were quantified by one group of the authors, who measured the vertical fusion within BVFs. Other authors analyzed CT scans, designating each fracture as either A or B, based on lesser or greater soft tissue distortion relative to the configuration of bone fragments. The interval between trauma and surgery was also determined.

RESULTS

Among the 15 patients with a postoperative motility outcome poorer than the median (86 degrees or less), four (27%) had A fractures; 11 (73%) had B fractures. Among the 15 patients with an outcome better than the median (88 degrees or more), 10 (67%) had A fractures; five (33%) had B fractures. Differences were more defined away from the median. Among five patients with B fractures and better than the median result, three (60%) had surgical repair during the first week after injury. Among the 11 patients with B fractures and less than the median result, one (9%) had repair during the first week.

CONCLUSIONS

Postoperative motility is influenced by soft tissue-bone fragment relationships. Whether the outcome can be altered by earlier surgery in selected cases will be determined by prospective studies.

Periocular deep cutaneous basal cell carcinoma

PURPOSE

The distinction between benign and malignant cutaneous periocular lesions can be difficult, as the clinical history and appearance are often quite similar. When present, typical cutaneous changes are often helpful in distinguishing between benign and malignant neoplasms. However, when tumors lack characteristic epidermal change, histopathologic examination may be necessary to confirm the diagnosis. The authors present their experience in the evaluation and management of two patients with periocular basal cell carcinoma who were initially diagnosed as having benign cysts.

METHODS

The case records for two patients with periocular basal cell carcinoma were reviewed. Preoperative and postoperative photographs were available for comparison in one case. For each patient, the medical history, clinical presentation, histology, and surgical outcome were reviewed.

RESULTS

In each case, the periocular mass was initially diagnosed as a benign process. Histopathologic examination following excisional biopsy established the diagnosis of basal cell carcinoma in both patients. Following biopsy, residual tumor was removed by the Mohs micrographic technique. There were no surgical complications and no tumor recurrences during follow-up of one year and eight years.

CONCLUSIONS

Periocular basal cell carcinoma may mimic benign cystic lesions of the central face. Incorrect diagnosis may result in delayed or inappropriate therapy, or failure to submit seemingly benign lesions for histopathologic examination. Definitive treatment requires complete excision with histologic margin control.

Acute dacryocystitis as a presenting sign of pediatric leukemia

PURPOSE

To report acute dacryocystitis with preseptal cellulitis as the presenting sign of leukemia in a child.

METHODS

Case report and literature review.

RESULTS

During the initial evaluation of a 17-month-old child with epiphora, left lower eyelid swelling, and a tender left medial canthal mass, a complete blood cell count demonstrated pancytopenia. Bone marrow biopsy disclosed replacement of normal cellular architecture with a dense infiltrate of leukocyte blast forms. DNA analysis disclosed a translocation between chromosome 10 and 11, consistent with the diagnosis of nonlymphocytic leukemia. Although the adjacent lower eyelid cellulitis responded to intravenous antibiotics, lacrimal sac distention decreased only after chemotherapy was initiated.

CONCLUSIONS

Dacryocystitis with preseptal cellulitis can be a presenting sign of leukemia. This blood malignancy should be considered in patients whose leukocyte counts do not correlate with their clinical presentation.

Deep transorbital approach to the apex and cavernous sinus

Tumors of the orbital apex are difficult to approach through a standard lateral orbitotomy exposure. The transcranial approach has been described, but it requires an open craniotomy as well as dissection through the annulus of Zinn in its tight superior segment to reach intraconal and inferior lateral tumors. It is well recognized that the transcranial approach is optimal only for tumors of the superomedial orbital apex. Our study demonstrates that by enlarging the bony incision of a classic lateral orbitotomy to include a generous marginotomy and removing the deep sphenoid wing up to the superior orbital fissure, good exposure of the lateral orbital apex can be obtained. Tumors of the apex, including those that extend slightly into the cavernous sinus, can be removed from the cranial nerves and extraocular muscle origins in en face fashion, providing optimal ability to identify the delicate neurovascular structures of the orbital apex and avoid damage to them. The operating microscope is extremely useful for bony and soft tissue dissection. We report four benign tumors of the orbital apex removed using this approach. Two tumors encroached slightly into the cavernous sinus. Three of four patients were told that they had inoperable tumors. By use of the deep orbital apex approach described, all four tumors were successfully exposed and removed. Visual and motor function was unchanged or improved in all four patients, with the exception of one tumor that incorporated the inferior division of the third cranial nerve; in that patient, the transected nerve was anastomosed microscopically, and partial return of function was noted. The transorbital ophthalmic approach to tumors of the inferolateral orbital apex has significant potential advantages in comparison with a frontal craniotomy approach.

Carcinoma of the male breast metastatic to both orbits

We report the case of a 43-year-old man who presented with painless proptosis of the right eye of 6 weeks' duration. Examination demonstrated a tense right orbit and decreased vision and extraocular motility bilaterally. Diagnostic evaluation included computed tomographic imaging of the head and orbits, a therapeutic trial of high-dose systemic corticosteroids, and orbital biopsy, which revealed the presence of metastatic adenocarcinoma. The primary tumor was found to be an estrogen-receptor-positive, infiltrating ductal adenocarcinoma of the right breast. Therapy included lumpectomy of the breast mass, orbital irradiation, and hormonal therapy. Metastatic carcinoma of the breast should be considered in the differential diagnosis of orbital neoplastic disease in the male patient.

Orbital blow-out fractures: correlation of preoperative computed tomography and postoperative ocular motility

BACKGROUND/PURPOSE

Although the management of orbital blow-out fractures was controversial for many years, refined imaging with computed tomography (CT) helped to narrow the poles of the debate. Many orbital surgeons currently recommend repair if fracture size portends late enophthalmos, or if diplopia has not substantially resolved within 2 weeks of the injury. While volumetric considerations have been generally well-served by this approach, ocular motility outcomes have been less than ideal. In one series, almost 50% of patients had residual diplopia 6 months after surgery. A fine network of fibrous septa that functionally unites the periosteum of the orbital floor, the inferior fibrofatty tissues, and the sheaths of the inferior rectus and oblique muscles was demonstrated by Koornneef. Entrapment between bone fragments of any of the components of this anatomic unit can limit ocular motility. Based on the pathogenesis of blow-out fractures, in which the fibrofatty-muscular complex is driven to varying degrees between bone fragments, some measure of soft tissue damage might be anticipated. Subsequent intrinsic fibrosis and contraction can tether globe movement, despite complete reduction of herniated orbital tissue from the fracture site. We postulated that the extent of this soft tissue damage might be estimated from preoperative imaging studies.

METHODS

Study criteria included: retrievable coronal CT scans; fractures of the orbital floor without rim involvement, with or without extension into the medial wall; preoperative diplopia; surgical repair by a single surgeon; complete release of entrapped tissues; and postoperative ocular motility outcomes documented with binocular visual fields (BVFs). Thirty patients met all criteria. The CT scans and BVFs were assessed by different examiners among the authors. Fractures were classified into 3 general categories and 2 subtypes to reflect the severity of soft tissue damage within each category. "Trap-door" injuries, in which bone fragments appeared to have almost perfectly realigned, were classified as type I fractures. In the I-A subtype, no orbital tissue was visible on the sinus side of the fracture line. In the I-B subtype, soft tissue with the radiodensity of orbital fat was visible within the maxillary sinus. In type II fractures, bone fragments were distracted and soft tissue was displaced between them. In the II-A subtype, soft tissue displacement was less than, or proportional to, bone fragment distraction. In the II-B subtype, soft tissue displacement was greater than bone fragment distraction. In type III fractures, displaced bone fragments surrounded displaced soft tissue in all areas. In the III-A subtype, soft tissue and bone were moderately displaced. In the III-B subtype, both were markedly displaced. Motility outcomes were quantified by measuring the vertical excursion in BVFs. The interval between trauma and surgical repair was also determined.

RESULTS

Among the 15 patients with a motility outcome in BVFs which was poorer than the median (86 degrees or less of single binocular vertical excursion), 4 patients (27%) had type A fractures; 11 patients (73%) had type B fractures. Among the 15 patients with a better outcome than the median (88 degrees or more), 10 patients (67%) had type A fractures; 5 patients (33%) had type B fractures. These differences became more defined as analysis moved away from the median. Among 5 patients with type B fractures and better than the median result in BVFs, 3 patients (60%) had surgical repair during the first week after injury. Among the 11 patients with type B fractures and less than the median result, 1 patient (9%) had repair during the first week.

CONCLUSIONS

When the CT-depicted relationship between bone fragments and soft tissues is considered, a wide spectrum of injuries is subsumed under the rubric of blow-out fractures. In general, greater degrees of soft tissue incarceration or displacement, with presumably greater intrinsic damage and subsequent fibrosis, appear to result in poorer motility outcomes. Although this retrospective study does not conclusively prove its benefit, an urgent surgical approach to selected injuries should be considered.

Combined embolization and surgical treatment of arteriovenous malformation of the orbit

We examined three patients with arteriovenous malformation of the orbit. At initial examination, all patients had a slowly progressive mass effect combined with congestive symptoms and clinical signs typical of an orbital vascular lesion. Arteriovenous malformation of the orbit was diagnosed on the basis of clinical and radiographic assessment, including the use of digital subtraction angiography and in one patient, magnetic resonance imaging. Treatment of each patient involved neuroradiologic embolization of the vascular lesion followed by surgical excision. Transient complications of endovascular management occurred. In one patient particulate emboli migrated into the central retinal artery after postembolization orbital surgical excision; consequent focal ischemic retinopathy contributed to short-term visual field deficits, which eventually resolved spontaneously. In another patient, spasm of the ophthalmic artery occurred during embolization, resulting in a transient afferent pupillary defect and loss in visual acuity to 20/60, which resolved over the subsequent week. High-flow orbital vascular lesions represent a considerable treatment challenge because of the complex anatomic and hemorrhagic characteristics of the malformation. Neuroradiologic characterization and embolization as a preoperative adjuvant is not without risk but offers an important advantage in the treatment of these formidable lesions. A combination of endovascular and surgical management may allow otherwise inoperable lesions to be treated successfully.

Mycotic keratitis by Drechslera spicifera

The Drechslera state of Cochiobolus spicifer, Nelson 1964, was isolated from a case of keratomycosis. The patient, a 19 year old man, showed a large corneal ulcer with hypopyon associated with the introduction of dust. The direct examination of several scrapings revealed dark-brown hyphae. This species has been reported as a casual agent of a nodular granulomatous mass in the foot of a cat and in the skin of a horse.