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Purpose: Metformin use has been associated with a decreased risk of age-related macular degeneration (AMD) progression in observational studies. We aimed to evaluate the efficacy of oral metformin for slowing geographic atrophy (GA) progression., Design: Parallel-group, multicenter, randomized phase II clinical trial., Participants: Participants aged ≥ 55 years without diabetes who had GA from atrophic AMD in ≥ 1 eye., Methods: We enrolled participants across 12 clinical centers and randomized participants in a 1:1 ratio to receive oral metformin (2000 mg daily) or observation for 18 months. Fundus autofluorescence imaging was obtained at baseline and every 6 months., Main Outcome Measures: The primary efficacy endpoint was the annualized enlargement rate of the square root-transformed GA area. Secondary endpoints included best-corrected visual acuity (BCVA) and low luminance visual acuity (LLVA) at each visit., Results: Of 66 enrolled participants, 34 (57 eyes) were randomized to the observation group and 32 (53 eyes) were randomized to the treatment group. The median follow-up duration was 13.9 and 12.6 months in the observation and metformin groups, respectively. The mean ± standard error annualized enlargement rate of square root transformed GA area was 0.35 ± 0.04 mm/year in the observation group and 0.42 ± 0.04 mm/year in the treatment group (risk difference = 0.07 mm/year, 95% confidence interval = -0.05 to 0.18 mm/year; P  = 0.26). The mean ± standard error decline in BCVA was 4.8 ± 1.7 letters/year in the observation group and 3.4 ± 1.1 letters/year in the treatment group ( P  = 0.56). The mean ± standard error decline in LLVA was 7.3 ± 2.5 letters/year in the observation group and 0.8 ± 2.2 letters/year in the treatment group ( P  = 0.06). Fourteen participants in the metformin group experienced nonserious adverse events related to metformin, with gastrointestinal side effects as the most common. No serious adverse events were attributed to metformin., Conclusions: The results of this trial as conducted do not support oral metformin having effects on reducing the progression of GA. Additional placebo-controlled trials are needed to explore the role of metformin for AMD, especially for earlier stages of the disease., Financial Disclosures: Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article., (© 2023 by the American Academy of Ophthalmology.)

Background and Objective: Assess fluocinolone acetonide implant (FAc) effects on diabetic macular edema (DME) retinal thickness fluctuations., Patients and Methods: A post-hoc chart review of the real-world USER study analyzed patients receiving 0.2 μg/day FAc implant. The percentage of eyes with central subfield thickness (CST) of 300 µm or less were compared pre- and post-FAc implant; mean retinal thickness amplitude (RTA), retinal thickness standard deviation (RTSD), and two case studies were analyzed., Results: One hundred thirty patients (mean age: 69.6 years) presented; CST was available for 120 of 160 treated eyes. Mean RTA decreased significantly post-FAc implant (P < .001) regardless of baseline visual acuity (VA). Correlations with last-observed VA (R 2 ) were: RTA, 0.1197; retinal thickness standard deviation (RTSD), 0.1526; and area under the CST-time curve (AUC CST), 0.0981. After FAc implant, the percentage of eyes with CST of 300 μm or less was significantly greater versus baseline (P < .05)., Conclusions: Retinal thickness fluctuations significantly declined after FAc and correlated with improvement in VA. Both RTSD and RTA measures correlated more closely to last observed VA than AUC CST itself. [Ophthalmic Surg Lasers Imaging Retina. 2020;51:298-306.]., (© 2020 Riemann, Eaton, Cutino.)

Purpose: To report two cases of central retinal artery occlusion (CRAO) associated with vitreoretinal surgery., Observations: Two patients underwent vitreoretinal surgery and were diagnosed with CRAO on postoperative day one. Both had received retrobulbar anesthetic blocks, followed by pars plana vitrectomy in one patient and scleral buckling in the other patient. Best-corrected visual acuity at last follow-up was 20/40 and 20/400., Conclusions/importance: CRAO is a rare but serious adverse event after vitreoretinal surgery. The causative mechanism is not known in these patients.

Background and Objectives: To determine the rate of ocular hypertension (OHT) after dexamethasone intravitreal implant in routine clinical practice and identify patient characteristics associated with a risk for glaucoma surgery., Patients and Methods: The charts of 260 eyes from 221 patients with diabetic macular edema, retinal vein occlusion, uveitis, and macular edema secondary to various causes treated with one or more dexamethasone implants were reviewed. Intraocular pressure (IOP), medications, and glaucoma interventions were collected before and after implantation., Results: The mean baseline IOP was 14.3 mm Hg ± 3.6 mm Hg, and after receiving dexamethasone implant(s), 26.2% and 7.7% of patients had IOP greater than 25 mm Hg and 35 mm Hg, respectively. There was evidence (P < .001) of an association between preexisting glaucoma or glaucoma suspect status (103 eyes) and need for glaucoma surgery, and 4.62% (12 eyes) required glaucoma surgery., Conclusions: Secondary OHT induced by the dexamethasone implant can usually be controlled by medications, but the incidence of OHT requiring glaucoma surgery was high (4.62%) in our study relative to rates previously reported in the literature. All patients, especially those with preexisting glaucoma, should be advised of the possible need for glaucoma surgery prior to undergoing treatment with the dexamethasone implant. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:680-685.]., (Copyright 2018, SLACK Incorporated.)

The present study tested the effect of a bacterial lactone N-(3-oxododecanoyl)-homoserine lactone (C12-HSL) on the cytoskeletal and transcriptional genes and proteins in prostate adenocarcinoma (PA) cells (DU145 and LNCaP) and prostate small cell neuroendocrine carcinoma (SCNC) PC3 cells including their cellular viability and apoptosis. Our data indicate that cell migration and colony formation were affected in the presence of C12-HSL. C12-HSL induced apoptosis and altered viability of both PA and SCNC cells in a concentration dependent manner as measured by fluorescence and chemiluminescence assays. Compared to PCa cells, noncancerous prostate epithelial cells (RWPE1) were resistant to modification by C12-HSL. Further, the viability of PC3 cells in 3D matrix was suppressed by C12-HSL treatment as detected using calcein AM fluorescence in situ. C12-HSL treatment induced cytoskeletal associated protein expression of vinculin and RhoC, which may have implications in cancer cell motility, adhesion, and metastasis. IQGAP protein expression was reduced in DU145 and RWPE1 cells in the presence of C12-HSL. C12-HSL decreased STAT3 phosphorylation in DU145 cells but increased STAT1 protein phosphorylation in PC3 and LNCaP cells. Overall, these studies indicate that C12-HSL can trigger changes in transcription factors and cytoskeletal proteins and thereby modulate growth and migration properties of PCa cells.

Programmed death ligand 1 (PD-L1) expression in antigen-presenting cells and tumors can inhibit T cell-mediated immunity. In this study, PD-L1 mRNA and protein expression was evaluated in canine B cell lymphoma (CLL17-71), large T-cell leukemia (CLGL-90), B cell leukemia (GL-1) and primitive leukocyte round cell neoplasia (CLL-1390). Variable PD-L1 mRNA and protein were observed in these cells with high endogenous expression present in CLL17-71 cells. PD-L1 protein was also observed in canine patient B cell lymphoma tissues using immunostaining. PD-L1 and signal transducer and activator of transcription 1 ( STAT1 ) mRNA expression were reduced in the presence of mitogen-activated protein kinase kinase 1.2 (MEK1/2) inhibitors RDEA119 and AZD6244 in CLL 17-71 cells. RDEA119 had similar effect on PD-L1 and STAT-1 in IFN-γ activated CLL-1390 cells. Overall, these results indicate that PD-L1 is expressed in canine B cell lymphoma. Its inhibition by MEK1/2 inhibitors suggests a possible treatment strategy using targeted drugs which likely could enhance antitumor immune response., (© 2017 John Wiley & Sons Ltd.)

Purpose: To assess the ability of a novel imaging device to allow physicians to personalize therapeutic regimens based on objective patient drop administration data., Methods: A novel imaging system was used to record video of the drop technique of subjects in clinic (n=25) or at home (n=17) for 1 week. Video assessment by a reading center was compared with patient reporting and their prescribed regimen with respect to how many drops were applied and how many landed in the eye., Results: Reading center assessment of both drops dispensed and drops landing in the eye was significantly different from the prescribed regimen in the clinic (Pd=0.005, Pi<0.001, respectively) and at-home arms (Pd=0.003, Pi<0.001, respectively)., Conclusions: This imaging system is a powerful tool to help physicians tailor patient therapy more accurately, to help researchers evaluate new drop therapies with objective rather than subjective data, and to potentially facilitate better patient training for improved drug delivery.

Purpose: The pathophysiology of ocular hypertension (OH) leading to primary open-angle glaucoma shares many features with a secondary form of OH caused by treatment with glucocorticoids, but also exhibits distinct differences. In this study, a pharmacogenomics approach was taken to discover candidate genes for this disorder., Methods: A genome-wide association study was performed, followed by an independent candidate gene study, using a cohort enrolled from patients treated with off-label intravitreal triamcinolone, and handling change in IOP as a quantitative trait., Results: An intergenic quantitative trait locus (QTL) was identified at chromosome 6p21.33 near the 5' end of HCG22 that attained the accepted statistical threshold for genome-level significance. The HCG22 transcript, encoding a novel mucin protein, was expressed in trabecular meshwork cells, and expression was stimulated by IL-1, and inhibited by triamcinolone acetate and TGF-β. Bioinformatic analysis defined the QTL as an approximately 4 kilobase (kb) linkage disequilibrium block containing 10 common single nucleotide polymorphisms (SNPs). Four of these SNPs were identified in the National Center for Biotechnology Information (NCBI) GTEx eQTL browser as modifiers of HCG22 expression. Most are predicted to disrupt or improve motifs for transcription factor binding, the most relevant being disruption of the glucocorticoid receptor binding motif. A second QTL was identified within the predicted signal peptide of the HCG22 encoded protein that could affect its secretion. Translation, O-glycosylation, and secretion of the predicted HCG22 protein was verified in cultured trabecular meshwork cells., Conclusions: Identification of two independent QTLs that could affect expression of the HCG22 mucin gene product via two different mechanisms (transcription or secretion) is highly suggestive of a role in steroid-induced OH.

Background and Objective: Determine whether the new dexamethasone intravitreal implant (Ozurdex; Allergan, Irvine, CA) injector needle design can reduce the force needed for insertion when compared to the original needle design., Materials and Methods: In vitro testing assessed the force required for insertion from five new-design and five old-design Ozurdex needles on a synthetic test medium and explanted porcine eyes. Maximum penetration force was measured in grams-force, while the total work of the needle was measured in joules., Results: The new design required 29% and 68% less overall work to perform an injection in the synthetic medium (P = .0002) and porcine eyes (P = .009), respectively. The maximum force required to insert the new needle was 25% and 61% that of the old needle in the synthetic medium (P = .001) and porcine eyes (P = .007), respectively., Conclusion: The new needle design significantly reduces the force and work needed for insertion, which should improve physician control as well as patient safety and comfort., (Copyright 2014, SLACK Incorporated.)

Background and Objective: To determine whether a novel guarded 33-gauge injection device can make the intravitreal injection procedure faster and more comfortable for patients., Patients and Methods: Single-center, prospective, randomized interventional study. Seventy participants receiving bilateral injections on the same day had one eye injected with the 33-gauge injection device without a speculum and the other eye injected with a standard 30-gauge needle using a speculum. Length of time needed for the injection procedure was assessed, and subjects were asked to complete a questionnaire regarding their comfort level with each device during the injection procedure as well as immediately after, later that evening, and the next day., Results: Intravitreal injections using the 33-gauge injection device were significantly faster, but there was no significant difference in the incidence or levels of pain between the two needle types., Conclusion: The 33-gauge injection device may offer advantages over a standard 30-gauge needle when performing an intravitreal injection., (Copyright 2013, SLACK Incorporated.)

Purpose: To compare the incidence of sterile endophthalmitis after intravitreal triamcinolone acetonide injections during a 6 month period in 2006 to the same period in 2005 and determine the incidence after switching to intravitreal preservative-free triamcinolone acetonide., Methods: Retrospective multicenter interventional case series in which patients receiving intravitreal triamcinolone acetonide at three institutions from March 2005 to August 2005 and from March 2006 to August 2006 and intravitreal preservative-free triamcinolone acetonide from late summer 2006 through February 2007 were reviewed for the development of sterile endophthalmitis., Results: From March 2005 to August 2005, the rate of sterile endophthalmitis was 0% at all institutions. From March 2006 to August 2006, a statistically significant increase in sterile endophthalmitis was seen at all institutions with frequencies of 3.5% to 6.3% (P < 0.001). With transition to preservative-free triamcinolone acetonide, sterile endophthalmitis over the next 6 months decreased to 0% at two sites and to 2.5% (from 5.5%) at the third institution (P < 0.009)., Conclusions: A statistically significant increase in the rate of sterile endophthalmitis after intravitreal triamcinolone acetonide was seen in a 6 month period in 2006 when compared with the same period in 2005. Transition to preservative-free triamcinolone acetonide produced a frequency of sterile endophthalmitis similar to 2005.

The 5,10-methylenetetrahydrofolate reductase (MTHFR) gene plays a critical role in folate metabolism. Studies on the association between MTHFR polymorphisms and length changes in short tandem repeat DNA sequences [microsatellite instability (MSI)] are inconsistent. Using data from colon cancer cases (n=503) enrolled as part of an existing population-based case-control study, we investigated the association between MTHFR 677 and MTHFR 1298 polymorphisms and MSI. We also examined whether the association was modified by folate intake. Participants were case subjects enrolled as part of the North Carolina Colon Cancer Study. Consenting cases provided information about lifestyle and diet during in-home interviews as well as blood specimens and permission to obtain tumor blocks. DNA from normal and tumor tissue sections was used to determine microsatellite status (MSI). Tumors were classified as MSI if two or more microsatellite markers (BAT25, BAT26, D5S346, D2S123, and D17S250) had changes in the number of DNA sequence repeats compared with matched nontumor tissue. Tumors with one positive marker (MSI-low) or no positive markers (microsatellite stable) were grouped together as non-MSI tumors (microsatellite stable). MTHFR 677 and MTHFR 1298 genotypes were determined by real-time PCR using the 5' exonuclease (Taqman) assay. Logistic regression was used to calculate odds ratio (OR) and 95% confidence intervals (95% CI). MSI was more common in proximal tumors (OR, 3.8; 95% CI, 1.7-8.4) and in current smokers (OR, 4.0; 95% CI, 1.6-9.7). Compared with MTHFR 677 CC referent, MTHFR 677 CT/TT genotype was inversely associated with MSI among White cases (OR, 0.36; 95% CI, 0.16-0.81) but not significant among African Americans. Although not statistically significant, a similar inverse association was observed between MTHFR 677 CT/TT genotype and MSI among the entire case subjects (OR, 0.54; 95% CI, 0.26-1.10). Among those with adequate folate intake (>400 microg total folate), we found strong inverse associations between combined MTHFR genotypes and MSI (677 CC+1298 AC/CC, OR, 0.09; 95% CI, 0.01-0.59; 677 CT/TT+1298 AA, OR, 0.13; 95% CI, 0.02-0.85) compared with the combined wild-type genotypes (677 CC+1298 AA). This protective effect was not evident among those with low folate (<400 microg total folate) intake. Our results suggest that MTHFR variant genotypes are associated with reduced risk of MSI tumors under conditions of adequate folate intake, although the data are imprecise due to small numbers. These results indicate that the relationship between MTHFR genotypes and MSI is influenced by folate status.

Purpose: Posterior chamber foldable silicone intraocular lenses (IOLs) are becoming increasingly prevalent in patients undergoing a pars plana vitrectomy with fluid-air exchange. The authors report an important limitation of foldable silicone IOLs during fluid-air exchanges in pars plana vitrectomies., Methods: The charts of 18 pseudophakic patients with foldable silicone IOLs who underwent vitrectomy with fluid-air exchange by the authors were reviewed., Results: There was a statistically significant difference in the occurrence of condensation during fluid-air exchange between the group of patients with a capsulotomy versus those that did not have a capsulotomy (P = 0.003). Condensation limiting the view of the retina occurred during fluid-air exchange in 11 of 11 of the patients with foldable silicone lenses and a capsulotomy. Attempts to remove the condensation with a soft-tipped aspiration cannula resulted in limited view of the retina for 1 to 2 minutes in 6 of 11 patients. Use of a thin film of silicone oil restored the view in one patient. In the presence of an intact posterior capsule, condensation did not occur on identical foldable silicone IOLs in seven of seven patients., Conclusion: Recognition of the presence of a foldable silicone lens is important when an air-fluid exchange is anticipated. If a capsulotomy is present, the surgeon must be aware that condensation may limit the view of the retina severely during and after surgery. Intraoperatively, the view of the retina usually can be restored in short surgeries by wiping the posterior lens surface with a soft-tipped cannula, and in more complex surgeries by applying a thin film of silicone oil on the posterior surface of the lens.

B lymphocytes from tonsillar tissue of an asymptomatic HIV-1-seropositive subject were transformed with Epstein-Barr virus (EBV) and tested for the production of HIV-1-specific antibodies by ELISA, using purified HIV-1SF2.2F11, a monoclonal antibody derived from a transformed line, is of the IgG1 subclass and recognizes an epitope in the conserved region of the envelope transmembrane glycoprotein gp41, which is expressed on the surface of HIV-infected T cells. The antibody does not mediate the lysis of infected T cells in antibody-dependent cellular cytotoxicity (ADCC) assays and does not neutralize the infectivity of HIV-1SF2 or the homologous isolate HIV-1TT2.2F11 appears to be the first anti-gp41 human monoclonal antibody that enhances the infectivity of an HIV-1 strain (i.e., SF128A) in the absence of complement.

The effects of postmortem interval on dopamine D1 mRNA and D1 receptors were assessed in rat striatum under conditions simulating the handling of human brain tissue at 0, 6, 12, and 24 h postmortem. The amount of D1 mRNA was measured by both in situ hybridization film and emulsion autoradiography with [35S]dATP-labeled oligonucleotide probes. D1 receptor density was determined by autoradiography with [125I]SCH 23982. Neither the total amount of D1 mRNA in the striatum nor the frequency distribution of striatal cells expressing D1 mRNA varied with the postmortem interval. There was a modest but significant decrease (ca. 10%) in D1 receptors over the 24 h postmortem interval; this decrease occurred within the first 6 h postmortem, with no further decreases up to 24 h postmortem. These findings suggest that the effects of postmortem interval on D1 mRNA and receptors are minimal and should not limit an examination of possible alterations in dopamine D1 receptor mRNA and D1 receptors in the postmortem brains of humans with neuropsychiatric disease.

Bispecific murine monoclonal antibody 2B1, possessing dual specificity for the human c-erbB-2 protooncogene product and human Fc gamma receptor III (CD16) was evaluated for the ability to promote specific lysis of c-erbB-2-positive tumor cells in vitro. In short-term 51Cr release assays with human mononuclear cells as effectors and SK-Br-3 human breast cancer cells as targets, neither parental antibody of 2B1 mediated significant specific lysis, but bispecific antibody was as active as a chemical heteroconjugate, with 5 ng/ml of 2B1 causing half-maximal lysis at an effector/target ratio of 20:1 and 2 ng/ml 2B1 causing half-maximal lysis at an E/T ratio of 40:1. The cytotoxic targeting activity of 2B1 F(ab')2 fragment was the same as that of whole bispecific antibody, and the activity of whole 2B1 was not reduced when assays were performed in 100% autologous human serum, indicating that 2B1 binds effector cells through the CD16-binding site derived from parental antibody 3G8 rather than through its Fc portion. Variable inhibition of 2B1-mediated lysis was observed when autologous polymorphonuclear leukocytes from different donors were added to mononuclear effector cells at a 2:1 ratio; this inhibition was overcome at higher antibody concentration. 2B1 bispecific monoclonal antibody was also able to mediate targeted cytolysis using whole human blood as a source of effector cells or using effector or target cells derived from ovarian cancer patients.

A new combination of fluorescent dyes (rhodamine 123 and hydroethidine) was used to internally label hybridoma fusion partners. Murine hybridoma 520C9 (recognizing human c-erbB-2) was labeled with hydroethidine. Murine hybridoma 3G8 (recognizing human Fc gamma receptor III) was labeled with rhodamine 123, and verapamil was used to block rhodamine efflux via P-glycoprotein. Viability assays showed little cytotoxicity from these dyes at the concentrations used. The labeled cells were fused with polyethylene glycol, sorted for dual fluorescence on an Epics V cell sorter, and cloned. Hybrid hybridomas producing bispecific antibodies were selected for ability to promote lysis of SK-Br-3 breast cancer cells by human mononuclear cells. Several positive clones were obtained and shown to have a double content of DNA. Bispecific antibody produced by subclone 2B1 was purified by anion exchange chromatography and shown to bind both tumor cells and Fc gamma R III bearing cells. Using two parameter flow cytometric analysis, we were able to measure a 'bridging' effect of this bispecific antibody, which caused formation of complexes between PMNs and SK-Br-3 cells. Either parental antibody could compete with bispecific antibody to block such complexing. This fusion method provides several advantages over other techniques presently used (speed, convenience, low toxicity and automatic exclusion of dead cells) and can be applied to produce other hybrid hybridomas.

A number of 2,3-dimethoxy-5-(fluoroalkyl)-N-[(1-ethyl-2- pyrrolidinyl)methyl]benzamides (with or without a 6-hydroxy group) were synthesized and evaluated as dopamine D2 receptor ligands. The parent acids were synthesized via the Claisen rearrangement of the appropriate O-allyl ethers, which were derived from o-vanillic acid or 2,3-dimethoxysalicylic acid. A decrease in reactivity was found to be characteristic of pentasubstituted benzoates, and difficulties were encountered with the introduction of fluorine onto the ethyl side chains. The (fluoroethyl)- and (fluoropropyl)salicylamides were 5 times more potent than the corresponding benzamides in inhibiting [3H]spiperone binding to the D2 receptor. These (fluoroalkyl)salicylamides are of potential value for in vivo positron emission tomography (PET) studies upon the basis of their relatively selective, high potency binding affinity for the D2 receptor.

We report a new method for quantitating retinal blood vessel width from fluorescein angiogram negatives using a computerized image analyser. Interuser and intrauser variability were 3 to 4 times lower than reported with older methods. In addition, model blood vessels were used to test the accuracy of our method under four clinically relevant conditions: variations in vessel width, fluorescein concentration, flash intensity and background fluorescence. Although computed measurements were affected by vessel width, fluorescein concentration and flash intensity, the linearity of the actual versus computed width was maintained during wide variations in all four conditions (r = 0.95, P less than 0.0001). Accuracy was best achieved at a flash intensity of 150 W/sec and a fluorescein concentration of 45 micrograms/ml. The results of this study provide a better understanding of factors affecting the apparent width of retinal blood vessels in fluorescein angiograms. This technique should be useful in rapidly obtaining accurate measurements of blood vessel width from fluorescein angiograms.

Of 122 mouse monoclonal antibodies selective for human breast cancer, 13 immunoprecipitated an acidic glycoprotein from SK-Br-3 and ZR-75-30 human breast cancer cells. The antigen (BCA200) migrates with an apparent molecular weight of 200,000 on reducing and 180,000 on nonreducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis, suggesting a single polypeptide chain with a folded domain stabilized by a disulfide bond. Cross-blocking and sandwich immunoassays detected at least three distinct antigenic determinants on BCA200. Scatchard experiments measured 1,000,000 to 5,000,000 antigen copies per SK-Br-3 cell. The tissue distribution of BCA200 was studied using two monoclonals to different epitopes. Neither antibody stained any cells in human blood. When frozen sections of 20 normal human tissues were immunoperoxidase stained, the only positive structures were mucinous glands of colon, transitional epithelium of bladder, sweat glands of skin, and acinar epithelium of breast. Antibody 454C11 stained 16 of 21 breast tumor frozen sections and 9 of 12 breast cancer cell lines, while antibody 520C9 stained 5 of 20 breast tumors and 4 of 10 breast cancer lines. Cross-reaction was observed with lung, prostatic, pancreatic, endometrial, and ovarian cancer, but not with lymphoma, melanoma, colon, stomach, bladder, or esophageal cancer. When conjugated to ricin A chain, 10 of 13 antibodies produced immunotoxins selectively cytotoxic to SK-Br-3 breast cancer cells.

A patient with rheumatoid arthritis who was evaluated for dyspnea of six months' duration is described. Although no primary cardiac or parenchymal lung disease was identified, right heart catheterization revealed marked pulmonary hypertension. The patient was presumed to have pulmonary arteritis. Evaluation of her hyperproteinemia, however, led to the discovery of a polyclonal gammopathy with a marked increase in plasma viscosity. Although the classic clinical findings of the hyperviscosity syndrome were minimal, the patient underwent plasmapheresis, resulting in a marked reduction of pulmonary artery pressures (from 53 +/- 4 mm Hg, mean +/- SD, to 30 +/- 3 mm Hg, p less than 0.05) and pulmonary vascular resistance (from 707 +/- 63 dynes/second/cm5 to 421 +/- 72 dynes/second/cm5, p less than 0.05) concomitant with a return to normal plasma viscosity. Her dyspnea completely resolved. This represents the first successful treatment of pulmonary hypertension by plasmapheresis. Protein evaluation revealed the presence of intermediate complexes of IgG rheumatoid factor. The hyperviscosity syndrome should be considered in the differential diagnosis of pulmonary hypertension in patients with rheumatoid arthritis and other disorders associated with a polyclonal or monoclonal gammopathy. Pulmonary hypertension secondary to the hyperviscosity syndrome is reversible by plasmapheresis. Immunosuppressive therapy that reduces immunoglobulin production may provide a means of long-term treatment.