Unraveling the molecular basis of cannabidiolic acid methyl Ester's anti-depressive effects in a rat model of treatment-resistant depression

Major depressive disorder (MDD) stands as a significant cause of disability globally. Cannabidiolic Acid-Methyl Ester (CBDA-ME) (EPM-301, HU-580), a derivative of Cannabidiol, demonstrates immediate antidepressant-like effects, yet it has undergone only minimal evaluation in psychopharmacology. Our goal was to investigate the behavioral and potential molecular mechanisms associated with the chronic oral administration of this compound in the Wistar Kyoto (WKY) genetic model of treatment-resistant depression. Male WKY rats were subjected to behavioral assessments before and after receiving chronic (14-day) oral doses of CBDA-ME (0.5 mg/kg), 15 mg/kg of imipramine or vehicle. At the end of the study, plasma corticosterone levels and mRNA expression of various genes in the medial Prefrontal Cortex and Hippocampus were measured. Behavioral outcomes from CBDA-ME treatment indicated an antidepressant-like effect similar to imipramine, as oral ingestion reduced immobility and increased swimming duration in the Forced Swim Test. Neither treatment influenced locomotion in the Open Field Test nor preference in the Saccharin Preference Test. The behavioral impact in WKY rats coincided with reduced corticosterone serum levels, upregulated mRNA expression of Cannabinoid receptor 1, Fatty Acid Amide Hydrolase, and Corticotropin-Releasing Hormone Receptor 1, alongside downregulation of the Serotonin Transporter in the hippocampus. Additionally, there was an upregulation of CB1 mRNA expression and downregulation of Brain-Derived Neurotrophic Factor in the mPFC. These findings contribute to our limited understanding of the antidepressant effects of CBDA-ME and shed light on its potential psychopharmacological mechanisms. This discovery opens up possibilities for utilizing cannabinoids in the treatment of major depressive disorder and related conditions.

Designed proteinoid polymers and nanoparticles encapsulating risperidone for enhanced antipsychotic activity

BACKGROUND

Nanoparticles (NPs) incorporating drug formulations can be used to facilitate passage through biological barriers including the blood-brain barrier (BBB) and increase drug delivery and bioavailability. Hence, NP-based administration may enhance the efficiency of current antipsychotics. Encapsulation within NPs can resolve aqueous solubility problems that not only reduce permeability through the BBB but also affect targeting. The present study describes a new drug delivery system based on proteinoid NPs to explore the possibility of improving drug efficacy. Risperidone (RSP) is a commonly used atypical antipsychotic medication, and was therefore selected for encapsulation by proteinoid NPs.

RESULTS

Proteinoid polymers with high molecular weight and low polydispersity were synthesized from L-amino acids and poly-L-lactic acid (PLLA) by thermal step-growth polymerization mechanism. RSP-loaded proteinoid NPs were then prepared using a self-assembly process in the presence of RSP, followed by PEGylation. The optimal PEGylated RSP-loaded NPs were characterized in terms of diameter and size distribution, drug loading, ζ-potential, cytotoxicity, biodistribution, and psychopharmacological effects. The findings indicate significantly higher antipsychotic activity of drug-loaded proteinoid NPs compared to free RSP.

CONCLUSIONS

Proteinoid NPs enhance RSP delivery and may potentially increase drug efficiency by reducing dosage and side effects.

Synergistic effect of AS101 and Bryostatin-1 on myeloid leukemia cell differentiation in vitro and in an animal model

We evaluated the synergistic activity of AS101 (ammonium trichloro-(dioxoethylene-0-0')-tellurate) with the protein kinase C (PKC) activators, Bryostatin-1 and phorbol-12-myristate-13-acetate (PMA), on human myelocytic leukemia cell differentiation in vitro, and in a mouse model. Use of AS101 with Bryostatin-1 or with a low concentration of PMA resulted in the differentiation of HL-60 cell line to cells with characteristics of macrophages. A similar synergistic effect was found in vivo. Compared with mice treated with AS101 alone or with Bryostatin-1 alone, the infiltration of leukemic cells into the spleen and the peritoneum of mice treated with both compounds, as well as the number of the HL-60 colonies extracted from those organs, were markedly reduced. The antitumor effects were associated with significantly prolonged survival (100% for 125 days) of the treated mice. Finally, the mechanism of action of this antitumor effect was explored, and was found to involve the Ras/extracellular signal-regulated kinase signaling pathway. Combined treatment with AS101 and Bryostatin-1 synergistically increased p21(waf1) expression levels independently of p53. Upregulation of p21(waf1) was necessary for HL-60 cell differentiation, which was found to be both c-raf-1 and mitogen-activated protein kinase dependent. This study may have implications for the development of strategies to induce differentiation in myeloid leukemias, myelodysplasias and possibly in other malignancies.

Intravascular lymphomatosis--an indolent or aggressive entity?

Intravascular lymphomatosis (IVL) is a rare malignancy characterized by neoplastic proliferation of lymphoid cells within the lumens of arteries, small veins and capillaries. We report four patients with IVL and review the recent world literature, relating to incidence, clinical features and possible therapy. In these cases diagnosis was established coincidentally in one patient after prostatectomy. This patient eventually had central nervous system involvement. In two other patients IVL was diagnosed from skin lesions. In the fourth case the diagnosis was established at post-mortem examination, where involvement of most organs was evident but particularly kidneys, myocardium, gastrointestinal tract and lymph nodes. Therapy was given to three patients, but the disease progressed in two and they both died with evidence of central nervous system involvement, while the third patient has had a good partial response to combination chemotherapy but has relapsed within two months of completing chemotherapy. As evident from our patients and the literature review IVL has a variable clinical course and currently, there appears to be no effective therapy for this rare disorder.

Polyvalent melanoma cell vaccine induces delayed-type hypersensitivity and in vitro cellular immune response

Patients with melanoma metastatic to distant sites or at high risk for recurrent melanoma have been treated with a polyvalent melanoma cell vaccine (MCV) in phase II protocols. We assessed in vivo and in vitro cell-mediated responses to MCV in 163 patients who had undergone surgical resection of American Joint Committee on Cancer stage III melanoma. During the first 4 months of vaccine immunotherapy, 135 patients (83%) responded by developing a positive delayed-type hypersensitivity reaction > or = 6 mm to MCV. In a mixed lymphocyte tumor cell reaction using peripheral blood lymphocytes, 35 of 42 patients (83%) showed a recall proliferative response to one or more of the three cell lines of MCV. There was a significant correlation between delayed-type hypersensitivity reaction and mixed lymphocyte tumor cell reaction (P = 0.013). After 4 months of MCV therapy, 8 of 11 patients had an increased mixed lymphocyte tumor cell reaction to autologous melanoma cells. During the first 4 months of vaccine therapy, 16 of 33 patients developed more than a 50% increase in cytotoxic T-cell activity against one of the cell lines of MCV. Overall survival was significantly prolonged in patients with a positive delayed-type hypersensitivity reaction (P = 0.0054) and/or increased cytotoxic T-cell activity (P = 0.02). These findings suggest that MCV induces specific T-cell responses which are correlated with clinical course; the data also suggest that some of these responses are directed against autologous melanomas and may play a major role in controlling the progression of melanoma.

Aberrant expression of gangliosides in human renal cell carcinomas

Aberrant and elevated ganglioside expression has been observed in neoplasms, and has been shown to be an important marker of tumor progression. We therefore studied the gangliosides of renal cell carcinoma (RCC) by analyzing gangliosides from 18 RCC biopsies, 10 RCC lines and 5 normal kidney biopsies. A comparison of tumor with normal tissue revealed a significant difference in individual ganglioside expression in which the former consistently expressed eight major gangliosides, GM3, GM2, GM1, GD3, GD1A, GD2, GD1B and GT1B, according to the nomenclature of Svennerholm. There was a notable significant mean increase in the expression of GM2, GM1 and GD1A and a significant decrease in the expression of GD3 in tumor tissue compared with normal kidney tissue. Compared with tumor biopsy tissue, RCC cell lines showed a significant decrease in the expression of GM3, but a significant increase in GM2, GM1 and GD2. There was a marked increase in a pathway gangliosides (GM2, GM1, and GD1a) in RCC biopsies and cell lines compared with normal kidney. These studies indicating that RCC have markedly aberrant ganglioside expression similar to neural origin tumors may relate to the activation of a ganglioside pathway enzymes. Gangliosides expressed on RCC tumors may be important markers of tumor progression and target antigens for immunotherapy.

Modulation of histamine type II receptors on CD8+ T cells by interleukin-2 and cimetidine

CD8+ T cells are known to play a major role in regulating immune functions under normal and disease conditions. In this study a radioligand binding assay was used to quantitate histamine type II (H2) receptors on activated T cells. The objective was to examine the expression of H2 receptors on T cells during activation with interleukin-2 (IL-2) and treatment with cimetidine. Activated suppressor T cells induced by concanavalin A+IL-2 showed a significant (p less than 0.01) increase in H2 receptors compared to the control nonactivated T cells. The T cells expressing the H2 receptors were identified as CD8+ cells; those among them that had an enhanced level of H2 receptors were identified as CD25+. Treatment of activated suppressor cells with the H2 receptor antagonist cimetidine at a concentration of 10(-5) M significantly reduced the number of H2 receptors. Suppressor cells induced by Con A+IL-2 were able to suppress both IgG and IgM production that was reversible with cimetidine. Incubation of lymphocytes with 50 U/ml IL-2 alone in 3-day culture significantly (p less than 0.005) enhanced H2 receptor expression. These studies demonstrate that activated suppressor T cells that are CD8+CD25+ have enhanced levels of H2 receptors and can be modulated by cimetidine.

Interleukin 4 alone and with gamma-interferon or alpha-tumor necrosis factor inhibits cell growth and modulates cell surface antigens on human renal cell carcinomas

Immune cytokines have been shown to play important roles in regulating immune cell functions as well as neoplastic cells. Interleukin-4 (IL4), primarily known as a B-cell growth factor, can also activate and differentiate other immune cells. This cytokine has recently been shown to have immunotherapeutic benefit in tumor-bearing hosts. The present study assessed the effect on human renal cell carcinoma cell lines of recombinant IL4 alone and in combination with recombinant gamma-interferon (IFN) or recombinant alpha-tumor necrosis factor (TNF). IL4 inhibited cell growth of all lines at 250-500 units/ml in a differential manner. Expression of IL4 receptors was demonstrated on renal cell carcinomas. Overall, IFN (500 units/ml) alone inhibited cell growth; however, TNF (500 units/ml) was not as strong an inhibitor. When IL4 was combined with IFN or TNF there was a significant augmentation of cell growth inhibition and modulation of cell morphology of the cell lines. Tumor-associated ganglioside antigens (NeuAc alpha 2-3Gal beta 1-4Glc beta 1-1'Cer, NeuAc alpha 2-8NeuAc alpha 2-3Gal beta 1-4Glc beta 1-1'Cer, GalNAc beta 1-4 (NeuAc alpha 2-3)Gal beta 1-4Glc beta 1-1'Cer, and GalNAc beta 1-4(NeuAc alpha 2-8NeuAc alpha 2-3)Gal beta 1-4Glc beta 1-1'Cer) HLA class I, HLA-DR, and beta 2-microglobulin on the cell surface of renal cancer lines were assessed by flow cytometry and radiometric binding assay. IL4 alone or in combination with other cytokines modulated HLA class I and HLA-DR expression. IL4 and IFN consistently enhanced NeuAc alpha 2-8NeuAc alpha 2-3Gal beta 1-4Glc beta 1-1'Cer and GalNAc beta 1-4(NeuAc alpha 2-8NeuAc alpha 2-3)Gal beta 1-4Glc beta 1-1'Cer expression on individual cell lines. The study demonstrated that IL4 alone or in combination with other cytokines can significantly inhibit growth, and modulate the expression of surface major histocompatibility and tumor-associated antigens of renal cell carcinomas.

Modulation of human melanoma cells by interleukin-4 and in combination with gamma-interferon or alpha-tumor necrosis factor

Immune cytokines have been shown to play important roles in regulating immune cell functions. Interleukin-4 (IL4), originally described as a B-cell growth factor, is known to activate and differentiate other immune cells. IL4 has been given as an immunotherapeutic to tumor-bearing hosts. In this report, we set out to determine whether IL4 can directly modulate growth and expression of surface antigens on human melanoma cells. The effect of recombinant IL4 alone and in combination with recombinant gamma-interferon (IFN) or recombinant alpha-tumor necrosis factor (TNF) on melanoma cell lines was examined. IL4 significantly inhibited cell growth of all cell lines examined at 100-500 units/ml; but a dose-dependent differential response to individual cell lines occurred. The effect of IL4 was augmented by combination with IFN or TNF. Melanoma-associated ganglioside antigens (GM3, GD3, GM2, GD2) and human leukocyte antigen class I and DR on the cell surface of melanoma cells were assessed by flow cytometry and/or a radiometric binding assay. IL4, IFN, or TNF alone enhanced human leukocyte antigen class I, DR, and beta 2-microglobulin antigen expression. IL4 alone and in combination with IFN or TNF increased the GM3/GD3 ratio expression. GD2 was enhanced significantly by IL4, IFN, and TNF. Pretreatment of melanoma with IL4 or with other cytokines prior to stimulation with peripheral blood lymphocytes significantly enhanced mixed lymphocyte tumor reaction activity as compared with non-treated melanoma used as stimulators. These studies demonstrate that IL4 alone or in combination with IFN and TNF can modulate melanoma growth activity and surface antigen expression to a more differentiated and immunogenic phenotype.

Ganglioside GM2 expression on human melanoma cells correlates with sensitivity to lymphokine-activated killer cells

Ganglioside GM2 is expressed on cell surface membranes of a variety of human malignant cells and has been demonstrated to be immunogenic in humans. We have assessed the role of the antigen GM2 on melanoma cells as a recognition structure for lymphokine-activated killer (LAK) cells. LAK cells were generated by stimulation of non-adherent peripheral blood lymphocytes (PBL) from human donors with recombinant interleukin-2 (IL-2). The selection of target cells was based on GM2 content and included 11 human melanoma cell lines and 2 human leukemia lines. Using a single-cell binding assay, LAK cell binding to target lines expressing high levels of GM2 was significantly greater than to those expressing minimum GM2. This cell-binding was specifically inhibited by addition of purified GM2 but not by other gangliosides. LAK-melanoma cell-binding was also specifically inhibited by anti-GM2 monoclonal antibody (MAb). For further analysis LAK cell lysis of melanoma target cells expressing various amounts of GM2 was assessed. A significant correlation occurred with GM2 expression and LAK cell lysis (p less than 0.025; r = 0.623). Three other gangliosides commonly expressed on human melanoma, GM3, GD3 and GD2, had no correlation with LAK cell lysis. These studies suggest that GM2 on melanoma cells is a marker for LAK cell sensitivity, as well as indicate that GM2 is a potential target recognition structure for human LAK cells.

S-100 protein stimulates cellular proliferation

S-100 protein (S-100p) is a small, acidic, calcium-binding protein that is present (predominantly) in the cytoplasm of many types of cells including those of neuroectodermal origin, such as glial cells, schwann cells and melanocytes. In human melanoma cells S-100p is abundant relative to the small quantities expressed by normal melanocytes. We investigated the possibility that this protein may be a growth factor. Purified S-100p from bovine brain or human melanoma cells was added exogenously to human melanoma cells and peripheral blood lymphocytes (PBL) and their growth in the presence of different concentrations of S-100p was determined using a [3H]dT-uptake proliferation assay. The growth of melanoma cells was stimulated by S-100p at concentrations of 1.95-31.25 micrograms/ml. Slight inhibition of cell proliferation occurred at high concentrations (125 micrograms/ml). Maximum stimulation of PBL was at 31.25 micrograms/ml. PBL were not inhibited even at high concentrations of S-100p (125 micrograms/ml). PBL stimulation by S-100p did not require the presence of monocytes/macrophages. Though stimulation by S-100p is not restricted to a specific cell type, when released by melanoma cells it may function as an "autocrine" tumor growth factor. Other cells, such as PBL, coming in contact with S-100p are also stimulated to proliferate.

Surgical management of premacular fibroplasia

The results of pars plana vitrectomy and membrane peeling for premacular fibroplasia (PMF) were reviewed retrospectively for 88 eyes of 86 patients. Premacular fibroplasia was idiopathic in 61 eyes (69%) and postdetachment in 27 eyes (31%). All patients had a minimum follow-up of 12 months. Visual symptoms of blurring and metamorphopsia were reduced in 75 (85%) study eyes at the end of the follow-up period. Poor visual outcome was significantly related to preoperative cystoid macular edema and prolonged duration of visual blurring. Posterior retinal breaks occurred in three eyes (5%) with idiopathic PMF and five eyes (19%) with postdetachment PMF. Cataract progression was demonstrated in 35 eyes (48%) at 12 months of follow-up and 49 eyes (68%) at 24 months of follow-up, reflecting an incidence of cataract formation that has not been previously reported (to our knowledge) after limited vitrectomy and membrane peeling for PMF.

Transconjunctival anterior retinal cryotherapy for proliferative diabetic retinopathy

Transconjunctival anterior retinal cryotherapy (ARC) for proliferative diabetic retinopathy (PDR) in 408 eyes was reviewed retrospectively. Of 266 eyes available for analysis for treatment effect on neovascularization, 138 (52%) had reduced neovascularization at 6 months. Eighty (30%) had no change in neovascularization, and 48 (18%) had increased neovascularization at 6 months. Factors having a significant effect on reduction of neovascularization were duration of diabetes and severity of retinopathy. Of 238 eyes available for analysis for treatment effect on vitreous hemorrhage at 6 months, 118 (50%) had reduced vitreous hemorrhage, 80 (33%) had no change, and 40 (17%) had increased vitreous hemorrhage. Severity of vitreous hemorrhage significantly affected the outcome in the subgroup of eyes with both neovascularization and vitreous hemorrhage. Of the total 408 eyes in this series, at 6 months, 172 (44%) had improved visual acuity, 89 (23%) had no change, and 126 (33%) had decreased visual acuity. Retinal detachments developed in 17 eyes (4%) post-treatment, 68 eyes (17%) had significant recurrent vitreous hemorrhage, and 61 eyes (15%) eventually underwent vitrectomy.

New retinal detachment after pneumatic retinopexy

Thirteen cases of rhegmatogenous retinal detachment repaired by pneumatic retinopexy were reviewed retrospectively. All patients were followed for a minimum of 6 months after surgery. At the end of follow-up, retinal detachment repair by pneumatic retinopexy succeeded in nine cases (70%) and failed in four (30%). Within 2 days of pneumatic retinopexy, vitreous condensation and traction with new retinal tears and associated detachments in previously uninvolved quadrants developed in two patients. The occurrence of new retinal detachments in the early postoperative period after pneumatic retinopexy has not been previously observed.

Neovascular glaucoma: a retrospective analysis of treatment with peripheral panretinal cryotherapy

A retrospective analysis of thirty-one eyes in thirty patients with neovascular glaucoma (NVG) associated with proliferative diabetic retinopathy or venous occlusive disease was performed. Eyes treated with transconjunctival peripheral panretinal cryotherapy alone, or in combination with limited cyclocryotherapy had improvement or stabilization of visual acuity in 55%, reduction of intraocular pressure in 55%, and stabilization or regression of iris neovascularization in 70% of eyes at 12-14 months post-treatment. Transconjunctival peripheral panretinal cryotherapy alone, or in combination with limited cyclocryotherapy is recommended in the treatment of eyes with NVG and media opacities precluding photocoagulation therapy, or in eyes unresponsive to previous photocoagulation therapy.

Pseudophakic retinal detachments in the presence of various IOL types

A series of 600 pseudophakic retinal detachments in 578 patients undergoing surgical repair between 1974 and 1984 was reviewed. Patients with previous retinal surgery of less than six months follow-up were excluded. The series included 395 iris-fixated (IF) lenses, 130 anterior chamber (AC) lenses, and 75 posterior chamber (PC) lenses. The overall success rate for retinal detachment was 88% but was significantly better in the PC lens group and significantly worse in the AC lens group. Forty-one percent of all cases achieved 20/40 visual acuity or better, although the AC lens group did worse (28%), while the PC lens group did significantly better (48%). Risk factors that were predictive of failure also were identified. Many of these factors occurred more frequently in the AC lens group and probably are related to the overall worse outcome in eyes with AC lens implants. The implications of these results for retinal and cataract surgeons are discussed.

The Lincoff temporary balloon buckle

The Lincoff temporary balloon buckle is an equally effective alternative to more conventional techniques in the management of selected retinal detachments. We used this technique in the management of 45 selected primary retinal detachments operated on since Nov. 22, 1980. Initial complete retinal flattening was achieved in 42 eyes (93%). Two of the three eyes that initially did not show complete flattening ultimately went on to do well without further surgery. Redetachment occurred in three of the five aphakic eyes (60%) and in four of the 36 phakic eyes (11%). None of the retinas in the four eyes with intraocular lenses redetached. Conventional scleral buckling techniques were used in the one case of initial failure and in the seven cases of redetachment for a final success rate of 98% after an average follow-up of 13 months.

The question of ocular tolerance to intravitreal liquid silicone. A long-term analysis

The authors report a retrospective review of 407 eyes that received intravitreal liquid silicone between 1961 and 1984. Initial anatomical success was noted in 270 eyes (66.3%), while initial functional success was achieved in 103 eyes (25.3%). Ten years postoperatively, approximately half of the eyes with initial functional success still had functional vision (49.2%). These eyes had less advanced proliferative vitreoretinopathy and fewer inferior breaks than others. Recurrent retinal detachment rather than late complications was the predominant cause of functional failure in those eyes losing functional vision in less than ten years postoperatively. Late complications were common and frequently required therapeutic intervention. Intravitreal liquid silicone was of great benefit to many monocular patients, but of little benefit to the binocular patients in our series.

Limited retinal detachment. A retrospective analysis of treatment with transconjunctival retinocryopexy

Two hundred forty-one eyes with a "limited retinal detachment" were treated between 1967 and 1983 by transconjunctival retinocryopexy without scleral buckling. Follow-up ranged from 6 months to 10 years (mean, of 34 months). Anatomic reattachment was accomplished with retinocryopexy alone in 95% (228 eyes) of cases. Thirteen eyes (5%) were anatomic failures, but 12 of these were subsequently reattached with additional surgery. Risk factors for anatomic failure included multiple breaks, vitreous hemorrhage, and breaks with a rolled posterior edge. Visual results indicated that 229 eyes (95%) had stable or improved vision, while 12 eyes (5%) lost two or more Snellen lines. Causes for visual deterioration included premacular fibroplasia, proliferative vitreoretinopathy, and preexisting ocular pathology. Single breaks occurred in 172 eyes (71.4%), and multiple breaks in 69 eyes (28.6%). Associated clinical findings included high myopia (17%), surgical aphakia (12%), and retinal detachment in the fellow eye (27%).

Preoperative antibiotic soaking of silicone sponges. Does it make a difference?

A prospective randomized trial was carried out during the years 1974 to 1981 to determine whether preoperative antibiotic soaking of silicone sponges used in retinal detachment surgery would reduce the incidence of postoperative infection and extrusion. During this period 2972 consecutive primary scleral buckles were performed and in 921 (31%) of the cases an episcleral sponge was utilized either alone or in conjunction with a hard silicone encircling band. In alternate cases the sponge was soaked in an antibiotic solution for at least 30 minutes prior to insertion. In the remaining cases the sponge was not soaked. Overall, a statistically significant (P = 0.00018) seven-fold reduction in the rate of infection or extrusion was observed in cases where the silicone sponge was soaked preoperatively in antibiotics. An additional result of the study showed the rate of sponge removal was significantly increased by the use of multiple episcleral sponges (P = 0.00002).

Xenon arc photocoagulation of proliferative diabetic retinopathy. A review of 2688 consecutive eyes in the format of the Diabetic Retinopathy Study

In a retrospective study, 2688 eyes treated with xenon arc photocoagulation which would have qualified for inclusion in the Diabetic Retinopathy Study (DRS) were reviewed in the format of the DRS. When comparable risk groups were compared, the results of treatment were even more favorable than reported in the DRS without the severe complications attributed to xenon treatment in the DRS. A critical analysis of the DRS gives clues for the greater amount of visual loss found with xenon than argon in the DRS. Since these complications may be avoidable in some cases, and since xenon has been shown to be at least as effective as argon, it should continue to be used in the treatment of proliferative diabetic retinopathy.

Xenon arc photocoagulation of proliferative diabetic retinopathy (a review of 2688 consecutive eyes in the format of the diabetic retinopathy study--DRS)

Over 2500 xenon arc-treated eyes which would have qualified for inclusion in the DRS were reviewed in the format of the DRS. When comparable risk groups were compared, the results of treatment were even more favorable than reported in the DRS without the severe complications attributed to xenon treatment in the DRS. A critical analysis of the DRS gives clues for the greater amount of visual loss found with xenon than argon in the DRS. Since these complications may be avoidable in some cases and since xenon has been shown to be at least as effective as argon, it should continue to be used in the treatment of PDR.

An experimental model for the evaluation of vitrectomy instruments

A scleral window was designed for implantation in human autopsy eyes. This model provides direct visualization of the pars plana, vitreous base and peripheral retina. Using this model, one can directly observe vitrectomy instruments entering the globe, and can evaluate the cutting ability of a variety of instruments. The model can also be used to provide practical experience, analogous to clinical vitrectomy, and is therefore useful as a training device.

Aphakic retinal detachment. Management of the fellow eye

One hundred eighty-five patients with unilateral aphakic retinal detachment were studied to determine the frequency of retinal detachment in the fellow eyes undergoing cataract surgery. It was found to be four times higher than the frequency in those eyes that remained phakic (26% vs 7%). Despite the high incidence of detachment, 94% of the aphakic group had a final visual acuity of 20/60 or better in the second eye. At the time of surgery, the macula was still attached in only 17% of the 185 first eyes as compared to 57% of the 21 second eyes that developed an aphakic retinal detachment.

Early photocoagulation treatment of active histoplasmic maculopathy

Photocoagulation has proved to be an effective means of treating active presumed histoplasmic maculopathy. Xenon arc and argon laser light sources have proved equally effective when moderately intense, confluent burns are produced, and both are ineffective when mild lesions are produced. The membrane must be destroyed for the treatment to be effective; and, of course, the fovea must be preserved. In treating neovascular nets that are very close to the fovea, the argon laser offers the advantage of being capable of producing a sharper zone of delineation than the xenon arc (Fig. 6). When moderate amounts of subretinal fluid or hemoglobin overlie the neovascular membrane, it is very difficult to achieve the required degree of coagulation. Under these circumstances, it is best first to try to reduce the height of the sensory retinal detachment by means of systemic steroid treatment. If this is not successful, xenon photocoagulation has produced better coagulation effects than the argon laser. Analysis of our data indicates that resultant visual acuity can be correlated with pretreatment visual acuity (Fig. 5), with best results achieved before visual acuity deteriorates beyond the 20/40 level. The closer the edge of the neovascular membrane is to the fovea, the more risky it is to treat. However, these lesions are also those most apt to destroy central vision if left alone. It is encouraging to note that in only 3 of the 16 lesions in which the foveal edge was within 1 degree of the fovea did the visual acuity deteriorate to the 20/200 level, compared to 50 percent deterioration reported in the natural history of this disease [3].

Photocoagulation as a treatment of epithelial implantation cysts following cataract surgery

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Photocoagulation treatment of presumed histoplasmic choroidopathy

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