Effect of high-dose delivery on the attachment of meningiomas in Gamma Knife surgery: a retrospective study

BACKGROUND

Meningiomas have vascular supply from the tumor attachment on the dura mater. Gamma Knife radiosurgery (GKS) is known to have a vascular obliterating effect. This study aims to determine the benefits of high-dose irradiation to the tumor attachment compared to conventional dose planning in the long-term control of tumor growth with GKS.

METHODS

Two different dose plannings were retrospectively compared in 75 patients with meningioma treated with GKS as a primary treatment. Forty-three patients were irradiated over 20 Gy to the tumor attachment. The remaining 32 patients were treated with conventional-dose planning. Tumor growth control, reduction of enhancement on the gadolinium-enhanced magnetic resonance imaging (MRI), and neurological status were retrospectively assessed.

RESULTS

The maximum dose on the tumor attachment was significantly higher in the high-dose group (23 Gy) than in the conventional group (16 Gy). The tumor margin was irradiated with the median of the 50% isodose line in both groups. The prescription doses resulted in 14 Gy and 12 Gy, respectively. The tumor control rate achieved 91% in both groups during the median follow-up period of 54 months. A decrease of enhancement on follow-up MRI was noted in one patient in each group. Kaplan-Meier analysis revealed no statistical difference in the progression-free survival between the two groups. The number of patients with improved neurological status showed no statistical difference.

CONCLUSIONS

No obvious benefit of high-dose irradiation to the tumor attachment and margin was found in tumor control and neurological status in the long term.

Preoperative Evaluation of the Effects of Sigmoid Sinus Ligation with both Endovascular and Open-Field Occlusion Tests before Removal of Petroclival Tumors

Background  Surgery for petroclival tumors is very challenging for neurosurgeons because the position of the tumor in relation to the brainstem, cranial nerves, and posterior fossa vessels greatly restricts the surgical field. Some papers have described using sigmoid sinus ligation to open the surgical field; however, pre- and intraoperative evaluations of the safety of ligation have been limited, despite the risk of complications from venous insufficiency. Here, we describe our method of preoperatively evaluating the potential safety of a retrolabyrinthine transsigmoid approach with nondominant ipsilateral sigmoid sinus ligation (RLTSwSSL). Methods  A retrospective review was conducted on petroclival tumors treated over a 5-year period with RLTSwSSL after evaluation with both an endovascular balloon occlusion test (BOT) and an open-field sinus clipping occlusion test (COT). Changes in pressure of < 10 mm Hg and the absence of neurodegeneration during the tests indicated that it would be safe to proceed with permanent ligation. Results  Four patients with large petroclival tumors underwent surgery via RLTSwSSL after detailed preoperative evaluations with both BOT and COT. All patients had uneventful courses of recovery without developing any complications derived from venous insufficiency. Conclusion  In our case series, we have described a protocol for using both BOT and COT to evaluate the likely outcomes after sigmoid sinus ligation and thereby to improve safety. Further studies are needed to establish definite criteria for both occlusion tests that will ensure good outcomes.

Intradural Lipoma at the Craniocervical Junction Presenting with Progressing Hemiparesis: A Case Report

Intradural spinal lipomas are rare in an adult population. They are mostly asymptomatic and usually associated with spinal dysraphism in a pediatric population. We report a rare case of spinal lipoma without dysraphism and with progressing hemiparesis. A 60-year-old woman had incidental lipoma at the craniocervical junction observed for more than 5 years. Recently, she developed right-sided hemiparesis and sensory disturbance. Radiological studies revealed a large lipoma compressing the dorsal medulla and C1–C2 spinal cord. Standard midline suboccipital craniotomy and C1 laminectomy were performed, and the lipoma was removed subtotally. The lipoma showed severe adhesion to the dorsal medulla and C1 spinal cord; therefore, the excision was limited as internal debulking. Her neurological deficit subsided within 6 months after the decompressive surgery. Considering the benign nature of lipoma, internal decompression is a reasonable management for this lesion.

Bilateral Chronic Subdural Hematoma in the Posterior Fossa Treated with a Burr Hole Irrigation: A Case Report and Review of the Literature

Chronic subdural hematoma (CSH) in the posterior fossa is extremely rare. The surgical strategy is still controversial. We report a case of bilateral CSH in the posterior fossa successfully treated with a single-burr hole surgery. A 74-year-old man under anticoagulation and antiplatelet therapy developed headache and nausea during observation for an asymptomatic supratentorial CSH. Radiological examinations revealed appearance of bilateral CSH in the posterior fossa associated with hydrocephalus. Upon rapid deterioration of the patient's consciousness, an urgent treatment was required. A burr hole was made near the transverse-sigmoid junction on the left side to access the hematoma. No ventricular drainage was placed as his consciousness improved during the decompression of the hematoma. Postoperative computed tomography showed that bilateral CSH and hydrocephalus had been successfully treated. In bilateral CSH in the posterior fossa, there may be a connection between each side. CSH in the posterior fossa, when urgent, can be treated under local anesthesia with a unilateral burr hole irrigation.

Correlation of Appearance of MRI Perinidal T2 Hyperintensity Signal and Eventual Nidus Obliteration Following Photon Radiosurgery of Brain AVMs: Combined Results of LINAC and Gamma Knife Centers

Background A wide variety of radiologic changes occur within and adjacent to the nidus of arteriovenous malformations (AVMs) after stereotactic radiosurgery (SRS). Our objective was to study the magnetic resonance imaging(MRI)-defined changes following photon radiosurgery of AVMs and specifically to correlate the appearance of a perinidal T2 hyperintensity signal with the eventual angiographic obliteration of an AVM nidus in response to SRS treatment.

Material and Methods This retrospective study was conducted on 62 patients with brain AVMs who received photon SRS treatments between 2004 and 2017, using either a technique based on a linear accelerator at the Alexandria LINAC Radiosurgery Center in Egypt (21 patients/AVMs) or a technique based on a gamma unit at the Koto Memorial Gamma Knife Center in Japan (41 patients/AVMs). All patients included in the study had serial clinical and radiologic follow-ups for ≥ 2 years after SRS treatments.

Results In the combined study series of 62 patients/AVMs treated with photon SRS, the follow-up MRIs revealed that 50 AVMs (80.6%) showed nonvisualized nidus and 12 AVMs (19.4%) showed decreased nidus size. Radiation-induced changes, defined as appearance of perinidal T2 hyperintensities in post-SRS MRIs, occurred in 34 patients (54.8%). Of the 35 patients with available follow-up angiographic studies, 30 AVMs (85.7%) demonstrated complete nidus obliteration at a mean of 36 months (range: 8–66 months) after SRS. Of the 30 AVMs with both MRI evidence of a nonvisualized nidus and angiographic verification of complete nidus obliteration, 20 AVMs (66.7%) were associated with prior MRI evidence of the appearance of a perinidal T2 hyperintensity signal at an average of 12 months (range: 6–45 months) after SRS. Of the five AVMs with both MRI evidence of decreased nidus size and angiographic verification of partial nidus obliteration, four AVMs (80%) showed perinidal T2 hyperintensity signal on post-SRS follow-up MRIs. Lower Spetzler-Martin grade (p = 0.013), smaller AVM volume (p = 0.017), and appearance of post-SRS perinidal T2 hyperintensity signal (p = 0.007) were the statistically significant independent predictors of AVM obliteration. The appearance of perinidal T2 hyperintensity signal in the post-SRS MRIs had a sensitivity of 66.7%, a specificity of 20%, and an overall accuracy of 60% in predicting the eventual obliteration of the AVM nidus.

Conclusions The present study may help improve our current understanding of the mechanisms behind the radiation-induced tissue changes following AVM SRS. Because the SRS-induced hemodynamic changes within the AVM nidus initiate the cascade of the subsequent formation of perinidal vasogenic brain edema, the appearance of perinidal high T2 signal in the follow-up MRIs after SRS would be a valuable indicator of the AVM response to SRS. The development of perinidal hyperintensity was the strongest predictive factor of AVM obliteration (p = 0.007), with relatively high sensitivity (66.7%) and accuracy (60%) and fairly low specificity (20%), as a prognostic sign of eventual complete angiographic obliteration of the AVM nidus following SRS.

Single-stage total resection of giant dumbbell-shaped hypoglossal schwannoma: a case report

Extensive large dumbbell-shaped hypoglossal schwannoma is extremely rare, and total resection is nearly impossible. We present a case of a 61-year-old male with a giant-size hypoglossal schwannoma with moderate tongue atrophy. The tumor extended from the enlarged hypoglossal canal to the brainstem intradurally and the high cervical region extradurally. Through the extreme lateral infrajugular transcondylar (ELITE) skull base approach, the tumor was totally removed in a single-stage operation. Single-stage total resection is feasible by an experienced skull base team utilizing transcondylar skull base techniques and high cervical dissection.

A prospective phase II study of combined androgen blockade in patients with androgen receptor-positive metastatic or locally advanced unresectable salivary gland carcinoma

Background

There is no standard first-line chemotherapy for recurrent/metastatic (RM) or unresectable locally advanced (LA) salivary gland carcinoma (SGC).

Patients and methods

We conducted a single institution, open-label, single arm, phase II trial of combined androgen blockade (CAB) for androgen receptor (AR)-positive SGC. Leuprorelin acetate was administered subcutaneously at a dose of 3.75 mg every 4 weeks. Bicalutamide was administered orally at a daily dose of 80 mg. Patients were treated until progressive disease or unacceptable toxicities.

Results

Thirty-six eligible patients were enrolled. Thirty-three patients had RM disease and three patients had LA disease. The pathological diagnoses were salivary duct carcinoma (34 patients, 94%) and adenocarcinoma, NOS (two patients, 6%). The best overall response rate was 41.7% [n = 15, 95% confidence interval (CI), 25.5%-59.2%], the clinical benefit rate was 75.0% (n = 27, 95% CI, 57.8%-87.9%). The median progression-free survival was 8.8 months (95% CI, 6.3-12.3 months) and the median overall survival was 30.5 months (95% CI, 16.8 months to not reached). Additional analyses between treatment outcomes and clinicopathological factors or biomarkers including AR positivity, human epidermal growth factor receptor 2 status, and its complex downstream signaling pathway gene mutations showed no statistically significant differences. Elevated grade 3 liver transaminases and increased serum creatinine were reported in two patients, respectively. Discontinuation of leuprorelin acetate or bicalutamide due to adverse event occurred in one patient.

Conclusion

This study suggests that CAB has equivalent efficacy and less toxicity for patients with AR-positive RM or unresectable LA SGC compared with conventional chemotherapy, which warrants further study.

Clinical Trial Registration

UMIN-CTR (http://www.umin.ac.jp/ctr/index-j.htm), identification number: UMIN000005703.

Artificial Conditioner for Stored Organs

We have developed an artificial organ conditioning system in order not only to condition but also evaluate the viability for transplant graft of kidneys which have been stored for a long time and damaged by warm ischaemia following cardiac arrest. The conditioning system consisted of an artificial lung, a roller pump, an organ chamber and perfusate. The perfusate was prepared with electrolytes, fluorocarbon, amino acid, glucose, an oxygen scavenger and so on. Conditioning was performed by continuous perfusion under mild hypothermia at 24° C. Mildly damaged kidneys (0 and 30 minutes warm ischaemia rabbit kidneys) were well conditioned but severely damaged kidneys failed to produce urination. Our device successfully exposed the viability of stored kidneys and the successful conditioning of damaged kidneys due to warm ischaemia avoiding transplantation. By establishing our method, the harvesting of kidneys following cardiac arrest will be feasible.

Intraventricular Epithelioid Glioblastoma: A Case Report

BACKGROUND

Epithelioid glioblastoma, a high-grade, diffuse astrocytic tumor variant, comprises closely packed epithelioid cells and rhabdoid cells. This rare tumor usually develops in the cerebral cortex and diencephalon; however, in the case reported here, it was located intraventricularly.

CASE DESCRIPTION

A 47-year-old woman was referred to our hospital with a right intraventricular mass that had rapidly increased in size. On discovery of the tumor 3 years earlier at the referring hospital, the mass was small, calcified, and attached to the periventricular parenchyma. Over the next 2 years, the mass grew slowly, as observed on periodic magnetic resonance imaging scans. Forty days before the referral, the patient experienced headache and nausea, and marked growth and intratumoral hemorrhage were visible on a computed tomography scan of the head. The tumor was partially removed via a superior parietal lobule corticotomy. Histopathological examination confirmed an isocitrate dehydrogenase-wild-type epithelioid glioblastoma with a BRAF V600E mutation, but the original slow-growing lesion was no longer detected. Consequently, we assume that in this case, a low-grade glioma transformed into an aggressively malignant epithelioid glioblastoma.

CONCLUSIONS

We present the first case of an intraventricular epithelioid glioblastoma that might have arisen from a low-grade glioma with calcification. We recommend including this tumor variant in the differential diagnosis of lateral ventricle tumors.

Trigeminal neurofibroma in the infratemporal fossa arising from the inferior alveolar nerve: A case report

Solitary neurofibromas arising from cranial nerves are rare, and those arising from the peripheral divisions of the trigeminal nerve are even rarer. Although infratemporal fossa (ITF) masses are challenging to remove, certain approaches are considered feasible for this region. The present study reports a rare case of an ITF neurofibroma arising from the inferior alveolar nerve. The 27-year-old male patient presented with numbness of the right jaw. A radiological examination revealed a large mass occupying the ITF, from the mandible to the foramen ovale, originating from the inferior alveolar nerve in the mandible. The tumor was successfully excised via a transtemporal approach followed by a transoral-retromolar approach. A histological examination confirmed the diagnosis of neurofibroma. The present case demonstrates that a combination of the transtemporal and transoral-retromolar approaches may provide wide access to the ITF region.

Long-term outcomes of microvascular decompression and Gamma Knife surgery for trigeminal neuralgia: a retrospective comparison study

BACKGROUND

There is still no clear guideline for surgical treatment for patients with medically refractory trigeminal neuralgia (TN). When it comes to which surgical treatment to choose, microvascular decompression (MVD) or Gamma Knife surgery (GKS), we should know the long-term outcome of each treatment.

METHODS

We analyzed 179 patients undergoing MVD and 52 patients undergoing GKS followed for 1 year or longer. We evaluated the patient's neurological status including pain relief, complications and recurrence. Results were assessed with Barrow Neurological Institute (BNI) pain intensity and facial numbness scores. Overall outcomes were compared between the two groups based on pain relief and complications.

RESULTS

BNI pain intensity and facial numbness scores at the final visit were significantly lower in the MVD group than in the GKS group (P < 0.001, P = 0.04, respectively). Overall outcomes were superior following MVD than following GKS (P < 0.001). Following whichever treatment, there were initially high rates of pain-free status "without medication": 96.6% in the MVD group and 96.2% in the GKS group. However, 6.1% in the MVD group and 51.9% in the GKS group fell into a "with medication" state within median periods of 1.83 and 3.92 years, respectively (P < 0.001). Kaplan-Meier analysis revealed that pain recurred more often and later in the GKS group than in the MVD group (P < 0.001).

CONCLUSIONS

Considering the long-term outcomes, MVD should be chosen as the initial surgical treatment for patients with medically refractory TN.

Nervus Intermedius Neuralgia Treated with Microvascular Decompression: A Case Report and Review of the Literature

Nervus intermedius neuralgia is one of the craniofacial neuralgias, which is extremely rare compared with trigeminal or glossopharyngeal neuralgia. Despite its unique symptom, the aetiology remains unclear. We present a case of a surgically treated 36-year-old woman who suffered from paroxysmal stabbing deep-ear pain for over 10 years. Preoperative magnetic resonance imaging demonstrated a vascular loop compressing the root entry zone of the vestibulocochlear nerve between the seventh and eighth cranial nerves, suggesting nervus intermedius neuralgia as a cause of her pain. Surgical exploration revealed that the nervus intermedius was displaced upward by the anterior inferior cerebellar artery. Transposition of the artery from the brainstem relieved the patient’s neurological symptom immediately after the surgery, supporting the hypothesis that nervus intermedius neuralgia could be caused by neurovascular compression.

Constitutively active ABL family kinases, TEL/ABL and TEL/ARG, harbor distinct leukemogenic activities in vivo

ABL (ABL1) and ARG (ABL2) are highly homologous to each other in overall domain structure and amino-acid sequence, with the exception of their C termini. As with ABL, translocations that fuse ARG to ETV6/TEL have been identified in patients with leukemia. To assess the in vivo leukemogenic activity of constitutively active ABL and ARG, we generated a bone marrow (BM) transplantation model using the chimeric forms TEL/ABL and TEL/ARG, which have comparable kinase activities. TEL/ABL rapidly induced fatal myeloid leukemia in recipient mice, whereas recipients of TEL/ARG-transduced cells did not develop myeloid leukemia, instead, they succumbed to a long-latency infiltrative mastocytosis that could be adoptively transferred to secondary recipients. Swapping of the C termini of ABL and ARG altered disease latency and phenotypes. In a detailed in vitro study, TEL/ARG strongly promoted mast cell differentiation in response to stem cell factor or interleukin-3, whereas TEL/ABL preferentially induced myeloid differentiation of hematopoietic stem/progenitor cells. These results indicate that ABL and ARG kinase activate distinct differentiation pathways to induce specific diseases in vivo, that is, myeloid leukemia and mastocytosis, respectively. Further elucidation of the differences in their properties should provide important insight into the pathogenic mechanisms of oncogenes of the ABL kinase family.

Trigeminal Neuralgia Due to Red Vein Draining a Supratentorial Arteriovenous Malformation: Case Report

Trigeminal neuralgia (TGN) is rarely caused by arteriovenous malformation (AVM). The AVMs causing TGN are reported mostly in the ipsilateral posterior fossa. The culprit vessels are dilated feeding artery or nidus itself. We present a rare case of TGN caused by dilated draining veins from a supratentorial AVM. The patient suffered from TGN with an incidentally found large AVM, which had been left untreated. The neuralgia was successfully relieved by microvascular decompression. Dilated red veins compressed the nerve at the root entry zone and distant cisternal portion of the nerve. Technically, transposition is not practical for fragile, dilated red veins with high pressure. Interposition is safer method in this case.

Treatment Results of Gamma Knife Radiosurgery for Central Neurocytoma: Report of a Japanese Multi-Institutional Cooperative Study

OBJECTIVE

Central neurocytoma (CN) is a rare benign neuronal tumor, and a limited number of reports have described the usefulness of radiosurgery for a relatively large group of patients. We evaluated the effectiveness and outcomes of Gamma Knife radiosurgery (GKS) for CN in a Japanese multi-institutional study.

METHODS

We performed retrospective analysis of 36 patients with CN who were treated with GKS in 12 institutes in Japan. All patients underwent surgery before GKS. The median tumor volume at GKS was 4.9 mL (range, 0.07-23.4 mL), and the median radiation dose prescribed to the tumor margin was 15 Gy (range, 10-20 Gy). The median follow-up period was 54.5 months (range, 3-180 months).

RESULTS

The local tumor progression-free survival rates at 5 and 10 years were 94% and 86%, respectively. Three patients developed distant dissemination 16-90 months later. Overall progression-free survival was unrelated to the prescribed dose (<15 Gy vs. ≥15 Gy, P = 0.62), tumor size (<6 mL vs. ≥6 mL, P = 0.46), gender (P = 0.36), age (<30 vs. ≥30 years, P = 0.37), target of GKS (residual vs. recurrence, P = 0.90), and type of enhancement (homogeneous vs. inhomogeneous, P = 0.19). Two permanent complications occurred with 1 intratumoral hemorrhage and 1 radiation injury.

CONCLUSIONS

GKS is effective for CN because of its high rate of long-term local tumor control. GKS may have a potential role as a primary treatment for asymptomatic, relatively small tumors in the absence of hydrocephalus without surgical resection.

Trochlear Nerve Schwannoma Treated with Gamma Knife after Excision: A Case Report and Review of the Literature

Trochlear nerve schwannomas are extremely rare. We present a surgically excised case of trochlear nerve schwannoma followed by Gamma Knife (ELEKTA, Stockholm, Sweden) after histologic confirmation. A 52-year-old man presented with diplopia, gait disturbance, and sensory disturbance. Magnetic resonance imaging demonstrated a large cystic mass at ambient cistern on the right side. Subtotal excision followed by Gamma Knife surgery was undertaken. His neurologic symptoms disappeared with radiologic reduction in size at 15-month follow-up. Because Gamma Knife can manage trochlear nerve schwannomas well, surgical excision should be reserved for large ones and limited to subcapsular or subtotal removal with the expectation of possible recovery of neurologic dysfunction.

The development of laboratory tests for cancer in Japan with special reference to carcinoembryonic proteins

The present paper describes the present status of clinical tests for cancer in Japan. Since no cancer-specific substance has been found so far the clinical tests for cancer at present are always quantitative but not qualitative. Among these substances, alpha-fetoprotein is one of the most specific substances for cancer and its test is essential for diagnosis of hepatoma beins used worldwide. AFP is a specific product of liver cancer cells. The measurement of carcinoembryonic antigen in patient blood is a hopeful method for cancer diagnosis. This substance is not specifically produced by cancer cells, but the phenomenon of appearance in bloodstream appears to be cancer-specific. This may reflect the invasion of blood vessels in tissues such as colorectum, lung, etc., by infiltration of cancer cell. This is the reason for the appearance of CEA in a wide variety of cancers. There are many other clinical tests at present but these are only secondary aids for the diagnosis of cancer. This is the reason why the description concentrates mostly on AFP and CEA. The companies manufacturing the kits for these tests in Japan are also listed in this paper.

Trigeminal Neuralgia due to an Isolated Cerebral Varix: Case Report

Intracranial isolated varix is a very rare entity. Although it is usually asymptomatic, there are reports on symptomatic cases with hemorrhage or mass effect that mostly relate to arteriovenous fistulas or arteriovenous malformations. We present an extremely rare case of trigeminal neuralgia caused by an isolated varix. A 55-year-old woman had been experiencing right trigeminal neuralgia for 3 years. Computed tomography and magnetic resonance imaging revealed an enhanced mass lesion on the root entry zone of the right trigeminal nerve. Angiograms confirmed the mass was a varix arising on the vein connecting the basal vein of Rosenthal and the superior petrosal vein. Preoperative three-dimensional (3D) imaging clearly depicted the anatomical relation of the varix, adjacent vessels, and trigeminal nerve, which helped plan operative procedures. The varix with its parent vein was successfully transposed from the nerve without sacrificing any veins. Her pain disappeared immediately after the surgery and did not recur during a 30-month follow-up period. The 3D image contributed to making an accurate and safer operative plan especially for this rare case.

Ocular neuromyotonia treated by microvascular decompression: usefulness of preoperative 3D imaging

Ocular neuromyotonia is a rare ocular motility disorder characterized by involuntary contraction of extraocular muscles resulting in paroxysmal diplopia. Although ocular neuromyotonia is reported as a rare complication after radiation therapy, there are a few cases of ocular neuromyotonia in the absence of irradiation. In the reported cases the possibility of vascular compression has been suggested on radiological imaging. The authors report a case of ocular neuromyotonia treated by microvascular decompression of the third cranial nerve, supporting the hypothesis that neurovascular compression may play a role in its pathogenesis. The usefulness of preoperative 3D imaging for microvascular decompression is also discussed.

AV-65, a novel Wnt/β-catenin signal inhibitor, successfully suppresses progression of multiple myeloma in a mouse model

Multiple myeloma (MM) is a malignant neoplasm of plasma cells. Although new molecular targeting agents against MM have been developed based on the better understanding of the underlying pathogenesis, MM still remains an incurable disease. We previously demonstrated that β-catenin, a downstream effector in the Wnt pathway, is a potential target in MM using RNA interference in an in vivo experimental mouse model. In this study, we have screened a library of more than 100 000 small-molecule chemical compounds for novel Wnt/β-catenin signaling inhibitors using a high-throughput transcriptional screening technology. We identified AV-65, which diminished β-catenin protein levels and T-cell factor transcriptional activity. AV-65 then decreased c-myc, cyclin D1 and survivin expression, resulting in the inhibition of MM cell proliferation through the apoptotic pathway. AV-65 treatment prolonged the survival of MM-bearing mice. These findings indicate that this compound represents a novel and attractive therapeutic agent against MM. This study also illustrates the potential of high-throughput transcriptional screening to identify candidates for anticancer drug discovery.

Deletion of Ia-2 and/or Ia-2β in mice decreases insulin secretion by reducing the number of dense core vesicles

AIMS/HYPOTHESIS

Islet antigen 2 (IA-2) and IA-2β are dense core vesicle (DCV) transmembrane proteins and major autoantigens in type 1 diabetes. The present experiments were initiated to test the hypothesis that the knockout of the genes encoding these proteins impairs the secretion of insulin by reducing the number of DCV.

METHODS

Insulin secretion, content and DCV number were evaluated in islets from single knockout (Ia-2 [also known as Ptprn] KO, Ia-2β [also known as Ptprn2] KO) and double knockout (DKO) mice by a variety of techniques including electron and two-photon microscopy, membrane capacitance, Ca(2+) currents, DCV half-life, lysosome number and size and autophagy.

RESULTS

Islets from single and DKO mice all showed a significant decrease in insulin content, insulin secretion and the number and half-life of DCV (p < 0.05 to 0.001). Exocytosis as evaluated by two-photon microscopy, membrane capacitance and Ca(2+) currents supports these findings. Electron microscopy of islets from KO mice revealed a marked increase (p < 0.05 to 0.001) in the number and size of lysosomes and enzymatic studies showed an increase in cathepsin D activity (p < 0.01). LC3 protein, an indicator of autophagy, also was increased in islets of KO compared with wild-type mice (p < 0.05 to 0.01) suggesting that autophagy might be involved in the deletion of DCV.

CONCLUSIONS/INTERPRETATION

We conclude that the decrease in insulin content and secretion, resulting from the deletion of Ia-2 and/or Ia-2β, is due to a decrease in the number of DCV.