Background factors determining the time to intraocular lens dislocation.

PURPOSE: To clarify the characteristics of intraocular lens (IOL) dislocation requiring IOL suture or intraocular scleral fixation. METHODS: This retrospective consecutive case series included 21 eyes (21 patients) who required sutured or sutureless intrascleral IOL fixation following IOL extraction owing to IOL dislocation at the outpatient clinic in the Department of Ophthalmology, Saitama Red Cross Hospital, Japan, between January and December 2019. Medical records were retrospectively reviewed for background diseases, location of the dislocated IOL (intracapsular/extracapsular), insertion of a capsular tension ring (CTR), and the period from IOL insertion to dislocation. RESULTS: We included 21 eyes of 21 patients who required IOL suture or intrascleral fixation for IOL dislocation at our clinic from January to December 2019 were included. The most common background disease was pseudoexfoliation syndrome (four cases), followed by atopic dermatitis, dysplasia/dehiscence of the zonule, post-retinal detachment surgery, high myopia, and uveitis (three cases each). At the time of dislocation, the IOLs were either intracapsular (16 cases, including 3 cases with CTR insertion) or extracapsular (5 cases). The time from IOL insertion to IOL dislocation was 13.7 ± 8.1 years (maximum: 31.3 years, minimum: 1.7 years). CONCLUSIONS: In this study, all 21 cases represented late IOL dislocations occurring after 3 months postoperatively. Among these late IOL dislocation cases, IOL dislocation occurred in a short-medium period of time, especially in those with CTR insertion and weakness/dehiscence of the zonule, with an average of 3 to 5 years postoperatively. We propose referring to these cases as intermediate-term IOL dislocation.

Massive intraocular hemorrhage, presumably from the central retinal artery after cataract surgery, and difficult hemostasis during vitrectomy: a case report.

BACKGROUND: Severe intraocular hemorrhage is a rare complication of cataract surgery due to the recent generalization of minimal-incision cataract surgery. We report a case of a massive intraocular hemorrhage that probably originated from the central retinal artery after cataract surgery, in which hemostasis was difficult to achieve during vitrectomy. CASE PRESENTATION: An 86-year-old woman was referred to our department for intraocular lens (IOL) dislocation after undergoing cataract surgery. Massive intraocular hemorrhage was observed during the initial visit to our department. She underwent pars plana vitrectomy (PPV) and IOL repositioning under local anesthesia. However, the hemorrhage could not be removed completely because of continued massive intraoperative bleeding from the posterior fundus, and it was extremely difficult to achieve hemostasis during the initial surgery. At 7 days after the initial surgery, PPVs were performed under general anesthesia. Bleeding significantly decreased in the second surgery compared to the first. The bleeding probably originated from the central retinal artery on the optic disc; hemostasis was obtained by coagulation of the bleeding site with intraocular diathermy. After the second surgery, there was no exacerbation of bleeding and the patient's condition was stable. However, the patient's visual acuity showed no light perception after the second surgery. CONCLUSIONS: Massive intraocular hemorrhage may occur from the central retinal artery after undergoing cataract surgery. In such cases, surgery with general anesthesia with a lower maintained blood pressure (instead of surgery under local anesthesia) should be recommended, considering the possibility of difficult hemostasis in the event of bleeding from the retinal artery.

Diagnosis of cytomegalovirus corneal endotheliitis using surgically removed Descemet's membrane and endothelium despite negative results with aqueous humor PCR: a case report.

BACKGROUND: Cytomegalovirus (CMV) has been known to cause unilateral corneal endotheliitis with keratic precipitates and localized corneal edema, iridocyclitis, and secondary glaucoma. CMV endotheliitis is diagnosed based on clinical manifestations and viral examination using qualitative polymerase chain reaction (PCR) of the aqueous humor. CASE PRESENTATION: An 80-year-old woman was referred to our department for bullous keratopathy. Pigmented keratic precipitates were found in the right eye without significant anterior chamber inflammation. After 8 months there was inflammation relapse with mutton fat keratic precipitates and PCR on aqueous humor was performed, with negative results for CMV, herpes simplex virus, and varicella zoster virus. Keratic precipitates disappeared with steroid instillation, and Descemet-stripping automated endothelial keratoplasty (DSAEK) was performed for the right eye. CMV-DNA was positive at 6.0 × 102 copies/ GAPDH 105 copies in real time PCR of corneal endothelial specimen removed during DSAEK with negative results for all the other human herpes viruses. After diagnosis of CMV corneal endotheliitis, treatment with systemic and topical ganciclovir was initiated and there was resolution of symptoms. No recurrence of iridocyclitis or corneal endotheliitis was observed at 6 months follow up. CONCLUSIONS: This case report suggests that PCR should be performed using the endothelium removed during DSAEK for bullous keratopathy of an unknown cause, even if PCR for aqueous humor yields negative results.

Clinical Performance Evaluation of a High-Risk Human Papillomavirus Genotyping Test "Clinichip HPV" Using Cervical Scrape Specimens.

BACKGROUND: Persistent infection with high-risk human papillomavirus (HPV) is closely associated with cervical cancer development. In this study, the performance of the Clinichip HPV genotyping assay as a screening laboratory test for high-risk HPV infection was evaluated. METHODS: The genotypes of 74 cervical scrape specimens were tested using the Clinichip HPV assay and a conventionally employed HPV polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay. PCR sequencing was performed in cases with discrepant results between the Clinichip HPV test and PCR-RFLP. RESULTS: Genotyping using the Clinichip HPV assay and PCR-RFLP method resulted in 27% disagreement. PCR sequence results exhibited 79% and 21% consistency with the Clinichip HPV assay and PCR-RFLP method, respectively. Multiple infections were detected in 24.3% and 12.2% of the tested cases using the Clinichip HPV assay and PCR-RFLP method, respectively. CONCLUSIONS: The genotyping performance of the Clinichip HPV showed strong concordance with PCR sequencing, although this rate was partially diminished in cases with multiple HPV infections. The Clinichip HPV represents a suitable laboratory test for the clinical screening of high-risk HPV infections.

Poor intraoperative visibility and postoperative astigmatism associated with trabecular micro-bypass stent for corneal dystrophy: A case report.

RATIONALE: There are reports of safe cataract surgery in eyes with posterior polymorphous corneal dystrophy (PPCD); however, to our knowledge, there are no reports of minimally invasive glaucoma surgery (MIGS) in eyes with PPCD. Herein, we report a case of poor intraoperative visibility with gonioscopy, postoperative corneal edema, and corneal astigmatism in eyes with PPCD treated with trabecular micro-bypass stent combined with cataract surgery. PATIENT CONCERNS/DIAGNOSIS: A 78-year-old man was referred to our hospital for MIGS. He presented with bilateral corneal endothelial vesicular changes and band lesions. Endothelial cell density was 2983/2871 cells/mm2 (right/left eye), central corneal thickness was 581 µm/572 µm, best-corrected visual acuity values (Snellen equivalent) were 20/32 (right) and 20/100 (left), and corneal astigmatism was -2.7D in the right eye and -2.5D in the left eye. INTERVENSIONS/ OUTCOMS: After phacoemulsification and aspiration with intraocular lens implantation with a 2.4-mm corneal incision in both eyes, trabecular micro-bypass stents were inserted successfully despite the poor intraoperative visibility with gonioscopy. One week after surgery, the central corneal thickness was 614 µm/609 µm, and Descemet's membrane folds and mild corneal edema were observed. Best-corrected decimal visual acuity was 20/40 for the right eye and 20/50 for the left eye. In the left eye, total corneal astigmatism increased from -2.5D to -5.5D. Corneal astigmatism and edema showed gradual improvement. LESSONS: Although reports have shown that cataract surgery can be safely performed in eyes with PPCD, MIGS in eyes with PPCD may require caution regarding intraoperative visibility with gonioscopy and visual function in the early postoperative period.

Effects of reduction in intraocular pressure after trabeculotomy on axial length and intraocular lens selection.

PURPOSE: To investigate the relationship between intraocular pressure (IOP) and axial length (AL) and to compare the refractive predicted error in patients who have undergone cataract surgery alone or in combination with trabeculotomy. SETTING: Hospital. DESIGN: Single-center, retrospective, case-control. METHODS: The medical records of patients who had undergone cataract surgery alone or in combination with trabeculotomy using the Tanito microhook were retrospectively reviewed. Patients were grouped into cataract surgery alone (CAT) or cataract surgery combined with trabeculotomy (LOT) groups. Demographic data, preoperative and postoperative IOP and AL, and surgically induced astigmatism (SIA) were analyzed before and 1 month postoperatively to evaluate the interplay between IOP, AL, and refractive outcomes. RESULTS: 52 eyes (52 patients) underwent LOT, and 67 eyes (67 patients) underwent CAT. The mean IOP at baseline did not differ between the groups; the change in IOP (dIOP) was significantly higher in the LOT group than in the CAT group. The mean AL at baseline and the change in AL (dAL) were 24.0 ± 1.2 mm and 0.16 ± 0.11 mm, respectively, in the LOT group, and 23.8 ± 1.1 mm and 0.11 ± 0.070 mm, respectively, in the CAT group. The difference in dAL was also significant. In the LOT group, dIOP and dAL were significantly correlated. The mean SIA vectors did not significantly differ between the groups. CONCLUSIONS: AL decreased because of the reduction in IOP after cataract surgery combined with trabeculotomy. Consequently, the refractive target error was greater, and the postoperative refractive outcome showed a tendency toward hyperopia.

Performance evaluation of the automated morphological analysis of erythrocytes by CellaVision DM96.

BACKGROUND: Automated digital morphology systems are utilized for blood cell morphological examination. The aim of this study is to evaluate the accuracy and efficacy of RBC morphological anomaly screening using the CellaVision DM96 (DM96) automated image analysis system. METHODS: The automated analysis of RBC shape, size, and chromasia abnormalities was conducted on the DM96 using 478 blood samples. A manual microscopic review was independently performed. RESULTS: The DM96 preclassified samples as poikilocytosis-positive for 98% of cases with schistocytosis or echinocytosis, 97% of elliptocytosis, and 92% or 65% of cases that were positive for teardrop cells or for target cells, respectively. The accuracy of the DM96 in the detection of RBC size and chromasia abnormalities of iron deficiency anemia cases was higher than direct microscopic observation. CONCLUSIONS: Automated morphological analysis with the DM96 has potential utility in the morphological screening of RBC anomalies that are associated with disease.

Transsphenoidal meningocele: an anatomical study using human fetuses including report of a case.

An asymptomatic transsphenoidal meningoencephalocele was discovered incidentally by fiber laryngoscopic examination in a 62-year-old man suffering from hoarseness due to dysplasia of the vocal cord epithelium. To provide a better understanding of the pathogenesis of this anomaly, we performed histologic observations of paraffin-embedded specimens of 42 human fetal heads at 12-16 weeks of gestation. At these stages, ossification had started in the clivus but the sphenoid sinus was not developed. In contrast to the very low incidence of the intra- or trans-sphenoidal remnant of Rathke's pouch after birth, we found (1) the typical mid-line cleft of the sphenoid body in two specimens (2/42 or 4.8 %) and (2) a duct-like, sellar inferior protrusion ending in the sphenoid body in 12 specimens (12/42 or 28.6 %). The cyst-like structure in the protrusion (two specimens) seemed to be composed of obstructed veins. The intra- and trans-sphenoidal anomalies were observed more frequently in specimens without ossification of the sphenoid body than in those with ossification. However, irrespective of ossification, a cyst-like remnant of the most upper part of Rathke's pouch was always seen between the anterior and posterior lobes of the developing pituitary gland. In addition, the bursa pharyngea was seen in four specimens and we confirmed that the notochord was attached to the bursa in each case. The consistent remnant of the intrasellar Rathke's pouch appeared to explain the high incidence of Rathke's cleft cyst in adults. The relatively high incidence of intrasphenoidal anomalies in fetuses (14/42) suggested that the intra- or trans-sphenoidal remnant of Rathke's pouch was physiologically closed by ossification of the sphenoid body.

Clinical Outcomes of Phacoemulsification in Japanese Patients Receiving First and Revised Second-Generation Trabecular Microbypass Stents.

PURPOSE: This study evaluated the effectiveness and safety of first and revised second-generation trabecular microbypass stent insertion [iStent (IS) and iStent inject W (IW)] in cataract surgery. DESIGN: Single-center, retrospective, cohort study. METHODS: The study included 176 eyes that received trabecular microbypass stents combined with cataract surgery at the Saitama Red Cross Hospital between September 2017 and September 2021. Patients were divided into IS and IW groups depending on the implant type. Demographic characteristics, intraocular pressure (IOP), and the number of antiglaucoma medications (Med) were analyzed preoperatively and 12 months postoperatively. In addition, postoperative complications were compared between the groups. RESULTS: IS and IW were implanted in 86 eyes and 90 eyes, respectively. IOP and Med at 1, 3, 6, 9, and 12 months decreased significantly from baseline in both groups ( P = 0.04, P < 0.001, P < 0.001, P < 0.001, and P < 0.001, respectively, for IOP in the IS group; P = 0.02, P < 0.001, P < 0.001, P < 0.001, and P < 0.001, respectively, for IOP in the IW group; P = 0.03, P = 0.002, P < 0.001, P < 0.001, and P < 0.001, respectively, for Med in the IS group; and P < 0.001 for all time points for Med in the IW group). IOP did not vary significantly between the groups at 1, 3, 6, 9, and 12 months postoperatively. Med was significantly lower in IW than IS at 1, 3, 6, 9, and 12 months postoperatively ( P < 0.001, P < 0.001, P = 0.002, P = 0.002, and P = 0.002, respectively). Hyphema and IOP >30 mm Hg (spike) occurred in 1.2% and 4.4%, and 1.2% and 3.3% of patients in the IS and IW groups, respectively. The probability of successful discontinuation of medications at 12 months postoperatively was 10.5% and 41.1%, respectively ( P < 0.001). CONCLUSIONS: Postoperative Med was significantly lower in the IW group. Simultaneous insertion of IW in patients with glaucoma requiring cataract surgery may be preferred to IS because it reduces the burden of Med.

Induction of amyloid-ß(1-42) in the retina and optic nerve head of chronic ocular hypertensive monkeys.

PURPOSE: Recent studies have indicated that accumulation of amyloid ß(1-42) (Aß(1-42)), which is associated with the progression of Alzheimer disease, may also be responsible for retinal ganglion cell death in glaucoma. The purpose of this study was to investigate the expression and localization of Aß(1-42) in the retina and the optic nerve head (ONH) of monkeys with experimental glaucoma. METHODS: Five cynomolgus monkeys with a glaucomatous left eye at 4, 9, 11, 15, and 24 weeks after laser photocoagulation treatment were studied by immunohistochemical methods. Another two cynomolgus monkeys with a glaucomatous left eye at 133 weeks after laser photocoagulation treatment were used to measure Aß(1-42) concentrations in the retina by enzyme-linked immunosorbent assay. RESULTS: At 11 to 24 weeks after the laser photocoagulation treatment, Aß(1-42) was upregulated in the nerve fiber layer (NFL) and the ganglion cell layer (GCL) of the retina and the ONH, but the expression of amyloid precursor protein decreased in the NFL and ONH from levels at 9 weeks. The localizations of Aß(1-42) were merged in glial fibrillary acidic protein-positive astroglial cells but not phosphorylated neurofilament heavy- or nonphosphorylated neurofilament heavy-positive axons in the retina and the ONH. Likewise, Aß(1-42) concentrations in the retina of monkeys increased in the chronic stage of glaucoma. CONCLUSIONS: These findings indicate that the upregulation of Aß(1-42) after an intraocular pressure elevation could apply to monkeys since the structure of the ONH is more similar to humans than that of rodents.

Anterior Chamber Shallowing from the Early Stage of Surgery and Suprachoroidal Effusion during Clear Corneal Small-Incision Cataract Surgery: A Case Report.

Suprachoroidal effusion (SCE) is a rarely observed complication due to the recent generalization of clear corneal small-incision cataract surgery. We report a case of anterior chamber shallowing (ACS) from the early stage of surgery and SCE during clear corneal small-incision cataract surgery. A 69-year-old man was referred to our department for primary open-angle glaucoma and grade 2 nuclear cataract. The intraocular pressure (IOP) was 18 and 12 mm Hg in the right and left eyes with the instillation of three antiglaucoma eye drops in both eyes, respectively, and deep anterior chamber and normal axial length were observed. At the age of 70 years, which was 4 months after the initial visit to our department, the IOP of the right eye increased to 30 mm Hg. Hence, cataract surgery and microhook ab interno trabeculotomy (µLOT) of the right eye were scheduled. Mild ACS was observed during continuous curvilinear capsulorhexis (CCC), and ACS worsened as the surgery progressed, making the surgery progressively challenging. SCE was observed by fundus examination after phacoemulsification and cortex removal, and the wound was immediately closed with a suture. The IOP was 28 mm Hg on postoperative day (POD) 1 and decreased to 14 mm Hg on POD 5. SCE disappeared on POD 12. On POD 18, intraocular lens implantation into the bag and µLOT were performed under general anesthesia. Subsequently, the IOP decreased to 15 mm Hg 3 months after the surgery. Mild ACS was already present at the time of CCC, so it is possible that SCE occurred in the early stage of surgery. If ACS is observed intraoperatively, especially if there are SCE risk factors, such as hypertension, glaucoma, and lung cancer, as in this case, and even if the eye has deep anterior chamber and normal axial length preoperatively, fundoscopic examination should be performed even at an early stage of clear corneal small-incision cataract surgery to rule out SCE.

The effects of antithrombotic therapy in ab interno trabeculotomy with a spatula-shaped microhook.

To evaluate the effects of the discontinuation of antithrombotic drugs on intraocular pressure (IOP) reduction and complications from ab interno trabeculotomy for patients with glaucoma. We performed a retrospective chart review on the data of patients treated with antithrombotic agents who have undergone ab interno trabeculotomy through Tanito microhook combined with cataract surgery at the Asahi General Hospital and the Tokyo University Hospital, with 6 months of follow-up. The patients were classified into two groups depending on whether they discontinued (AT-) or continued (AT+) antithrombotic therapy during the perioperative phase. The demographics, pre- and postoperative IOP, medication score, best-corrected visual acuity (BCVA), and postoperative complications were analyzed preoperatively and postoperatively at 1 week and 1-6 months. The series included 44 eyes from 44 Japanese patients. The AT- and AT+ groups included 21 eyes from 21 patients and 23 eyes from 23 patients, respectively. The decrease in IOP from the baseline at 1 week postoperative was significantly different between the two groups (p = 0.009), but there were no significant differences observed in the other visits. Hyphema and IOP spikes exceeding 30 mmHg occurred in 10% and 10% of AT- participants, and in 43% and 26% of AT+ participants, respectively. Hyphema and spikes with hyphema occurred more frequently in the AT+ than in the AT- group (p = 0.02 and p = 0.05). The number of patients who had spikes was not significantly different (p = 0.27). In trabeculotomy using the Tanito microhook®, discontinuing antithrombotic therapy had better IOP-lowering effects and less postoperative complications.

[Hemorrhagic infarction complicated by obliteration of the superior sagittal sinus by depressed skull fracture after a hammer injury: a case report].

The authors have encountered a case of compound depressed skull fracture in a 59 year-old-man complicated by occlusion of the anterior 1/3 part of the superior sagittal sinus (SSS). He was hit by a hammer at the midline of the frontal region, and transferred to our emergency care unit. On admission, there was laceration of skin at the midline of the forehead, but the patient had no neurological deficit. Skull radiograph showed a depressed skull fracture over the SSS. Computed tomography (CT) scan showed a small brain contusion adjacent to the depressed fracture. Digital subtraction angiography (DSA) showed occlusion of the anterior 1/3 part of SSS, and extravasations of contrast medium from cortical arterioles and capillaries. CT taken at 4 hours after injury showed enlargement of the lesion with extravasations of contrast medium and the patient manifested consciousness disturbance at this point. Distribution of extravasations suggested the occurrence of hemorrhagic infarction. Elevation of the depressed skull was thus performed under general anesthesia. There was laceration of the dura 5 mm away from the SSS and lacerations of cortical vessels, but there was no apparent damage to SSS itself. The depressed bone was replaced with artificial bone. The patient was discharged without any neurological deficit. Preoperative angiography was helpful to understand the hemodynamics and risk of massive bleeding during the operation.

Usefulness of z-score mapping for quantification of extent of hypoattenuation regions of hyperacute stroke in unenhanced computed tomography: analysis of radiologists' performance.

OBJECTIVE: The purpose of this study was to evaluate the usefulness of z-score mapping method on neuroradiologists' performance in quantification of the extent of hypoattenuation regions of hyperacute stroke on unenhanced computed tomographic (CT) images by using the Alberta Stroke Programme Early CT Score system. METHODS: Twenty-one patients with infarction (<3 hours) were retrospectively selected. Five neuroradiologists interpreted CT images first without and then with z-score maps by using the Alberta Stroke Programme Early CT Score system. Their performances in the quantification of the extent of hypoattenuation were compared. RESULTS: Average accuracies for the quantification without and with the z-score maps were 82.6% and 86.6%, respectively (P < 0.0001). The average area under the receiver operating characteristic curve for detection of focal hypoattenuation significantly increased from 0.883 to 0.925 (P = 0.01) by use of z-score maps. CONCLUSIONS: The use of z-score mapping method has the potential to help neuroradiologists quantify the extent of hypoattenuation regions of hyperacute stroke on unenhanced CT images.

[Evaluation of capability of cell count and detection of tumor cells in cerebrospinal and body fluids by automated hematology analyzer].

Sysmex XE-5000 offers the body fluid modus which provides the opportunity to count and differentiate leukocytes in body fluids and cerebrospinal fluid (CFS). In this study, we evaluated the basic performance of this application using routinely obtained samples in comparison with manual counting. Reproducibility study yielded good results in samples with a high white blood cell (WBC) count, whereas relatively high imprecision was observed at low WBC counts. Linearity was established up to 1,500 cells/microL in CFS and 5,600 cells/microL in body fluid. The cell count by XE-5000 was highly correlated with that of the microscopic reference method. Highly fluorescent body fluid cells percent (HF-BF%) was observed in samples with tumor cells or activated macrophages, which provides information about the possible presence of tumor cells. In conclusion, total and differential WBC counts in body fluid and CFS can be reliably determined by XE-5000 in samples with increased cell counts. XE-5000 also provides screening information about the presence of tumor cells for further manual examination.

[Performance evaluation of the CellaVision DM96 system in WBC differentials].

Though differential counting of peripheral blood cells is an important diagnostic tool, this technique requires highly trained staff. Automation of differentials is desirable for economic and time-saving reasons. Recently, the CellaVision DM96 (DM96, CellaVision AB, Lund, Sweden) has been introduced as an automated cell analysis system capable of morphological classification of WBCs and RBCs in pheripheral blood smears. In this study, we routinely analyzed the blood samples from 216 patients by the DM96. The overall preclassification of WBC analysis accuracy value for the DM96 was 90.3%. Good correlation coefficients between final results of the DM96 and manual differentiation were observed. The DM96 system performed high sensitivity and specificity for blasts and immature granulocytes. Although the DM96 system operates more effectively in the normal blood samples than pathological ones, its ability of review slides on the computer screen with a cell-by-cell basis provides real-time collaboration between colleagues when they face the abnormal cells.

[Relevance of urinary protein/creatinine ratio and urinary abnormal casts].

OBJECTIVES: The quantification of 24 hrs urinary protein excretion is valuable for diagnosing and monitoring renal disease. However, because of its practical difficulties, the spot urinary protein/creatinine (P/C) ratio has been utilized. We aimed to evaluate the analytical performance of P/C ratio by comparing with the qualitative urinary protein values and the microscopic urine sediment analysis. METHODS: We obtained 5,538 urinary samples from the outpatients of Juntendo University Hospital. Testing for urinary P/C ratio was performed by Atlas Pro12 (cut-off 150 mg/g x Cr), urinary protein (proteinuria) was detected quantitatively by full-automated system ATLAS XL (cut-off 30 mg/dL). Microscopic exams were conducted following to the JCCLS reference method. RESULTS: The P/C ratio demonstrated higher sensitivity but lower specificity for urinary abnormal casts detected by microscopic exams compared to proteinuria (sensitivity; P/C 87%, proteinuria 77%. specificity; P/C 74%, proteinuria 93%). From the comparative study with microscopic exams, both P/C and proteinuria performed high positive rate (> 80%) for the granular cast type and mixture cast type. For the cellular cast type, however, the positive rate of P/C was 56% and that of proteinuria was only 36%. The overall abnormal casts by microscopic exams showed better correlation with the positive P/C ratio than proteinuria. CONCLUSION: This study emphasizes that a spot urine P/C ratio is useful in screening for the further microscopic exams. P/C ratio can be a convincing index of urinary protein excretion when attenuation urine is doubted.

Effects of pair-housing after social defeat experience on elevated plus-maze behavior in rats.

Social defeat experience in male rats causes an increase in anxiety-like behavior in the elevated plus-maze. Some researchers have suggested that housing rats socially following social defeat attenuates and/or prevents an increase in anxiety-like behavior. However, many other studies have shown that individual housing per se enhances anxiety-like behavior even in the absence of social defeat. In the present study, we assessed the relative contributions of the experience of social defeat and housing conditions on animals' performance in the elevated plus-maze. Rats were assigned to one of the following four groups: defeat/individual housing, defeat/pair-housing, non-defeat/individual housing, and non-defeat/pair-housing. The elevated plus-maze test was conducted 2 weeks after the defeat experience. Our results demonstrated that the defeat/individual housing group spent less time than the other groups in the open arms: moreover, there were no differences between the other three groups. These results confirm the claim that the group-housing of rats prevents an increase in anxiety-like behavior caused by defeat.