Inter-relationships among diet, obesity and hippocampal-dependent cognitive function.

Intake of a Western diet (WD), which is high in saturated fat and sugar, is associated with deficits in hippocampal-dependent learning and memory processes as well as with markers of hippocampal pathology. In the present study, rats were trained to asymptote on hippocampal-dependent serial feature negative (FN) and hippocampal-independent simple discrimination problems. Performance was then assessed following 7 days on ad libitum chow and after 10, 24, 40, 60, and 90 days of maintenance on WD, on ketogenic (KETO) diet, which is high in saturated fat and low in sugar and other carbohydrates, or continued maintenance on chow (CHOW). Confirming and extending previous findings, diet-induced obese (DIO) rats fed WD showed impaired FN performance, increased blood-brain barrier (BBB) permeability, and increased fasting blood glucose levels compared to CHOW controls and to diet-resistant (DR) rats that did not become obese when maintained on WD. For rats fed the KETO diet, FN performance and BBB integrity were more closely associated with level of circulating ketone bodies than with obesity phenotype (DR or DIO), with higher levels of ketones appearing to provide a protective effect. The evidence also indicated that FN deficits preceded and predicted increased body weight and adiposity. This research (a) further substantiates previous findings of WD-induced deficits in hippocampal-dependent FN discriminations, (b) suggests that ketones may be protective against diet-induced cognitive impairment, and (c) provides evidence that diet-induced cognitive impairment precedes weight gain and obesity.

High-risk corneal allografts are capable of stimulating complement dependent cytolytic antibodies.

PURPOSE: To prospectively characterize serum antibody responses in high-risk corneal allografts. METHODS: Orthotopic and heterotopic C3H (H-2k) corneas were transplanted to CB6F1 (H-2b/d) recipient mice. Individual serum samples were collected at days 7, 14, 21, and 28 from orthotopically and heterotopically grafted mice. Samples were tested for anti-C3H antibodies using an enzyme-linked immunosorbent assay (ELISA). Serum samples were also tested for the ability to lyse target cells in the presence of complement. RESULTS: In high-risk donor-host combinations, 100% corneal allograft rejection occurs in the absence of IgG1 production. Both orthotopic and heterotopic corneal allografts induced cytolytic complement fixing antibody isotypes. CONCLUSIONS: Allospecific corneal antibody may be involved in corneal graft rejection in high-risk donor-host combinations.

Results of a trial of combined propamidine isethionate and neomycin therapy for Acanthamoeba keratitis. Brolene Study Group.

PURPOSE: To characterize patients with Acanthamoeba keratitis and to evaluate the safety and efficacy of propamidine isethionate 0.1% ophthalmic solution (Brolene) when administered concomitantly with neomycin-polymyxin B-gramicidin ophthalmic solution (Neotricin) in the treatment of Acanthamoeba keratitis. DESIGN: Prospective, noncomparative case series. METHODS: The authors report the clinical characteristics and outcomes of patients who entered this multicentered, open-label, clinical trial. Eighty-three patients with Acanthamoeba keratitis representing 87 infected eyes entered the trial. RESULTS: Sixty (69%) of the 87 eyes enrolled had data analyzed for treatment efficacy and safety. Of these 60 eyes, 50 (83%) experienced treatment success. Thirty (60%) patients successfully treated adhered to treatment protocol guidelines. Patients who broke protocol had disease exacerbation during the maintenance therapy phase. The only eyes lost/enucleated were 7 of 17 in which penetrating keratoplasty was performed before eradication of the infectious agent. CONCLUSION: Propamidine isethionate and neomycin are an effective treatment for Acanthamoeba keratitis. Penetrating keratoplasty should be performed only for visual rehabilitation and not to "debulk" an active infection. The authors advocate treating patients with topical medications, mainly Brolene, until all organisms are eradicated. There should be no signs of infection for at least 3 months in the patients not receiving antiamebic medications before penetrating keratoplasty is performed.

Complications of combined radial thermokeratoplasty and incisional keratotomy.

PURPOSE: To report complications of radial thermokeratoplasty (RTK) when used in combination with either radial keratotomy (RK) or astigmatic keratotomy (AK). METHODS: RTK is a technique for the surgical correction of hyperopia and presbyopia. 600 degrees C burns are applied to the peripheral cornea for 0.3 seconds using a specialized cautery probe. The thermal energy generated shrinks stromal collagen and flattens the peripheral cornea. The central cornea is steepened producing a myopic shift. RESULTS: Two patients who had RTK in combination with either RK or AK are reported. Patient 1 was bilaterally hyperopic and presbyopic. The patient had RTK performed on the left eye in an attempt to make that eye myopic. The goal was to allow the left eye to be used for near vision. After RTK, the left eye was significantly overcorrected. The patient then had RK in the left eye which resulted in profound overcorrection with return of hyperopia. Postoperatively, examination revealed gaping of the RK incisions and poor epithelial wound healing. The patient also complained of severe ocular pain. Despite suturing the RK incisions, the eye remained hyperopic. The patient underwent two additional RTK procedures which failed to correct the induced hyperopia. The second patient had induced hyperopic astigmatism after undergoing RK. RTK was then performed to correct the hyperopia. However, the result was a worsening of the astigmatism. Two t-cut astigmatic keratotomies were then performed which improved the astigmatism but subsequently exacerbated the hyperopia. A second RTK procedure was then performed; however, it failed to correct the induced hyperopia. CONCLUSIONS: RTK is an unproved surgical technique for the correction of hyperopia and presbyopia that needs much further evaluation before broad clinical application can be supported.