Intraocular pharmacokinetics and safety of a humanized monoclonal antibody in rabbits after intravitreal administration of a solution or a PLGA microsphere formulation

Poly(lactic-co-glycolic) acid (PLGA) bioresorbable microspheres are used for controlled-release drug delivery and are particularly promising for ocular indications. The objective of the current study was to evaluate the pharmacokinetics and safety of a recombinant human monoclonal antibody (rhuMAb HER2) in rabbits after bolus intravitreal administration of a solution or a PLGA-microsphere formulation. On Day 0, forty-eight male New Zealand white rabbits (2.3-2.6 kg) were immobilized with intramuscular ketamine/xylazine, and the test materials were injected directly into the vitreous compartment. Group 1 animals received rhuMAb HER2 in 50:50 lactide: glycolide PLGA microspheres; Group 2 animals received rhuMAb HER2 in solution (n = 24/group). The dose for each eye was 25 microg (50 microl). After dosing, animals were sacrificed at 2 min, and on 1, 2, 4, 7, 14, 23, 29, 37, 44, 50, and 56 days (n = 2/timepoint/group). Safety assessment included direct ophthalmoscopy, clinical observations, body weight, and hematology and clinical chemistry panels. At necropsy, vitreous and plasma were collected for pharmacokinetics and analysis for antibodies to rhuMAb HER2, and the vitreal pellet (Group 1) was prepared for histologic evaluation. All animals completed the study per protocol-both treatments were well tolerated, and no suppurative or mixed inflammatory cell reaction was observed in the vitreal samples (Group 1) at any of the time points examined. Antibodies to rhuMAb HER2 were detected in plasma samples by Day 7 in both treatment groups, but infrequently in vitreous samples. There were no safety implications associated with this immune response. The in vitro characterization of the PLGA microspheres provided reasonable projections of the in vivo rhuMAb HER2 release kinetics (Group 1). The total amount of antibody that was released was similar in vitro (25.9%) and in vivo (32.4%). RhuMAb HER2 (Group 2) was cleared slowly from the vitreous compartment, with initial and terminal half-lives of 0.9 and 5.6 days, respectively. The volume of distribution approximated the vitreous volume in a rabbit eye.

Comparisons of the intraocular tissue distribution, pharmacokinetics, and safety of 125I-labeled full-length and Fab antibodies in rhesus monkeys following intravitreal administration

Access of recombinant proteins to the retina following intravitreal administration is poorly understood. A study was conducted in male Rhesus monkeys (15 to 28 mo of age; 2.8-3.3 kg) in order to compare the intraocular tissue distribution, pharmacokinetics, and safety of 125Iodine (I)-labeled full-length humanized rhuMAb HER2 antibody (148 kD) and of 125I-labeled humanized rhuMAb vascular endothelial growth factor Fab antibody (48.3 kD) following bilateral bolus intravitreal injection on day 0 (5 animals/group). The dose administered to each eye was 25 microg (9-10 microCi) in 50 microl. Animals were euthanatized on day 0 (1 hr postdose) and on days 1, 4, 7, and 14. Safety assessment included direct ophthalmoscopy, intraocular pressure measurements, clinical observations, body weight, and hematology and clinical chemistry panels. Blood and vitreous samples were collected daily (blood only) and at necropsy for pharmacokinetics and analysis for antibodies to the test materials; the ocular tissue distribution of the test material was evaluated by microautoradiography. All animals completed the study. Microautoradiography demonstrated that the full-length antibody did not penetrate the inner limiting membrane of the retina at any of the time points examined. In contrast, the Fab antibody fragment diffused through the neural retina to the retinal pigment epithelial layer at the 1-hr time point and persisted in this location for up to 7 days. Systemic exposure to test material was low but variable: the highest plasma concentration of the full-length antibody was 20.3 ng/ml, whereas plasma concentrations for the Fab antibody remained below the limit of quantitation (i.e., <7.8 ng/ml). An immune response to the test material was not evident in either treatment group. The half-life in vitreous was 5.6 days for the full-length antibody and 3.2 days for the Fab antibody. The shorter intravitreal half-life of the Fab antibody is related to its smaller size and its significant diffusion through the retinal layers. The differences in pharmacokinetics and tissue distribution that are noted between the full-length and Fab antibodies in this study identify potential therapeutic approaches that may be exploited in specific disease conditions.

Transketolase is a major protein in the mouse cornea

Earlier experiments in this laboratory identified a highly expressed 65-68-kDa protein in both mouse and human corneas (Cuthbertson, R. A. , Tomarev, S. I., and Piatigorsky J. (1992) Proc. Natl. Acad. Sci. U. S. A. 89, 4004-4008). Here, we demonstrate that this protein is transketolase (TKT; EC 2.2.1.1), an enzyme in the nonoxidative branch of the pentose-phosphate pathway, based on peptide and cDNA isolation and sequence analysis of mouse cornea protein and RNA samples, respectively. While expressed at low levels in a number of tissues, the 2.1-kilobase TKT mRNA was expressed at a 50-fold higher level in the adult mouse cornea. The area of most abundant expression was localized to the cornea epithelial cell layer by in situ hybridization. Western blot analysis confirmed TKT protein abundance in the cornea and indicated that TKT may comprise as much as 10% of the total soluble protein of the adult mouse cornea. Soluble cornea extracts exhibited a correspondingly high level of TKT enzymatic activity. TKT expression increased progressively through cornea maturation, as shown by Northern blot, in situ hybridization, Western blot, and enzymatic analyses. TKT mRNA and protein were expressed at low levels in the cornea prior to eye opening, while markedly increased levels were observed after eye opening. Taken together, these observations suggest that TKT may be a cornea enzyme-crystallin, and suggest that the crystallin paradigm and concept of gene sharing, once thought to be restricted to the lens, apply to other transparent ocular tissues.

Aequorea green fluorescent protein: simultaneous analysis of wild-type and blue-fluorescing mutant by flow cytometry

Aequorea green fluorescent protein (GFP) has been expressed in a variety of cell lines and host organisms. A recent report (Heim et al.: Proc Natl Acad Sci USA 91:12501-12504, 1994) has documented that a GFP mutant with a single amino acid substitution (tyrosine 66 to histidine; Y66H-GFP) elicits altered spectral properties. Whereas wild-type GFP emits with a maximum at approximately 509 nm (green fluorescence), Y66H-GFP fluoresces with a maximum at approximately 448 nm (blue fluorescence). In this study we employed available argon and krypton ion laser lines to investigate the impact of laser excitation wavelength on the detection of Y66H-GEP by flow cytometry. Using transiently transfected 293 cells, a cellular subpopulation with elevated blue fluorescence was detectable with excitation at 407 nm, but not with ultraviolet (UV), 458 nm, or 488 nm excitation. The blue-fluorescing cells were further documented to express Y66H-GFP by immunoblot analysis of sorted cells. Finally, we demonstrated the simultaneous analysis of both wild-type and Y66H-GFP in cotransfected 293 cells using 407 nm excitation while collecting blue fluorescence at 460 +/- 20 nm (Y66H-GFP) and green fluorescence at 525 +/- 25 nm (wild-type GFP). These studies illustrate the potential for assessing differential gene expression by simultaneously analyzing multiple GFP species with multiparameter flow cytometry.

Aequorea green fluorescent protein analysis by flow cytometry

The isolation and expression of the cDNA for the green fluorescent protein (GFP) from the bioluminescent jellyfish Aequorea victoria has highlighted its potential use as a marker for gene expression in a variety of cell types (Chalfie et al.: Science 263: 802-805, 1994). The longer wavelength peak (470 nm) of GFP's bimodal absorption spectrum better matches standard fluorescein filter sets; however, it has a considerably lower amplitude than the major absorption peak at 395. In an effort to increase the sensitivity of GFP with routinely available instrumentation, Heim et al. (Nature 373:663-664, 1995) have generated a GFP mutant (serine-65 to threonine; S65T-GFP) which possesses a single absorption peak centered at 490 nm. We have constructed this mutant in order to determine whether it or wild-type GFP (wt-GFP) afforded greater sensitivity when excited near their respective absorption maxima. Using the conventionally available 488 nm and ultraviolet (UV) laser lines from the argon ion laser as well as the 407 nm line from a krypton ion laser with enhanced violet emission, we were able to closely match the absorption maxima of both the S65T and wild-type forms of Aequorea GFP and analyze differences in fluorescence intensity of transiently transfected 293 cells with flow cytometry. The highest fluorescence signal was observed with 488 nm excitation of S65T-GFP relative to all other laser line/GFP pairs. The wt-GFP fluorescence intensity, in contrast, was significantly higher at 407 nm relative to either 488 nm or UV. These results were consistent with parallel spectrofluorometric analysis of the emission spectrum for wt-GFP and S65T-GFP. The relative contribution of cellular autofluorescence at each wavelength was also investigated and shown to be significantly reduced at 407 nm relative to either UV or 488 nm.

Molecular analyses of carbonic anhydrase-II expression and regulation in the developing chicken lens

The expression of carbonic anhydrase-II (CA-II) in the developing chicken lens was examined and compared with that in the retina of the chicken embryo. CA-II expression was measured by immunohistochemistry and radioimmunoassay during development, and CA-II mRNA was quantified by Northern blot and densitometric scanning and localized by in situ hybridization. A functional promoter of the chicken CA-II gene was identified by transfection of primary embryonic chicken lens epithelial cells and analyzed in deletion mutants. The results establish that CA-II makes up about 0.1% of the total soluble protein of the embryonic chicken lens, an amount insufficient to make it a candidate for an enzyme crystallin in this species. Lens fiber differentiation coincided with a loss of CA-II mRNA and protein; by contrast, CA-II persisted in the epithelial cells of the embryonic and mature lens. This and previous studies showed that CA-II amounts to as much as 3% of the protein of the embryonic chicken retina and follows a different developmental time course of expression; like the lens, CA-II decreases until day 10 in the embryonic retina, but, unlike the lens, it increases thereafter and plateaus at hatching. Progressive deletions of the 5' flanking regions (from position -1314 to +32) of the CA-II gene fused to the bacterial chloramphenicol acetyltransferase (CAT) reporter gene resulted in a gradual loss of promoter activity, consistent with an additive effect of putative cis-regulatory elements found in many crystallin genes. These experiments provide the foundation for a molecular analysis of the developmental and differential regulation of the CA-II gene in lens and retina.

Taxon-specific recruitment of enzymes as major soluble proteins in the corneal epithelium of three mammals, chicken, and squid

Studies of others have shown that class 3 aldehyde dehydrogenase is a major component of the epithelial cells of the mammalian cornea. Here we demonstrate by peptide sequencing that other major proteins of the corneal epithelium are also identical or related to enzymes in the human, mouse, kangaroo, chicken, and squid. Aldehyde dehydrogenase class 3 was found to be the major protein of human, mouse, and kangaroo corneal epithelial cells. Peptidyl prolyl cis-trans isomerase (cyclophilin) or a homologue thereof is strikingly abundant in the corneal epithelial cells of chicken, but not mammals, and appears to be absent from the cornea of squid. By contrast, enolase or its homologue is relatively abundant in both the mammalian and chicken corneal epithelial cells. In some instances, abundant enzymes are common to cornea and lens in the same species--for example, arginino-succinate lyase/delta 1-crystallin in the chicken and glutathione S-transferase-like protein in the squid; in other cases, the abundant proteins in the cornea have not been found as lens crystallins in any species--for example, aldehyde dehydrogenase class 3 and cyclophilin. These data suggest that enzymes and certain enzyme-crystallins have been recruited as major corneal proteins in a taxon-specific manner and may serve structural rather than, or as well as, enzymatic roles in corneal epithelial cells.

TNF alpha, IL-1 alpha and bFGF are implicated in the complex disease of GM-CSF transgenic mice

Transgenic mice aberrantly expressing the granulocyte-macrophage colony stimulating factor (GM-CSF) gene develop an unusual syndrome of blindness, tissue damage and wasting which is associated with accumulations of hemopoietic cells. In order to further characterize this disease state, we have used messenger RNA detection techniques to show that the genes for tumor necrosis factor (TNF alpha), interleukin-1 alpha (IL-1 alpha) and basic fibroblast growth factor (bFGF) are expressed at abnormally high levels in both macrophages and granulocytes in transgenic mice. Furthermore, since these cell types also express the GM-CSF transgene, it is likely that they are autocrine stimulated by GM-CSF. These observations raise the possibilities that, first, the expression of tumor necrosis factor alpha, interleukin-1 alpha and basic fibroblast growth factor in hemopoietic cells is a direct consequence of their autostimulation by GM-CSF, and second, that these cytokines may be responsible for some aspects of the transgenic mouse disease.

Differential expression of the two delta-crystallin/argininosuccinate lyase genes in lens, heart, and brain of chicken embryos

Chicken delta-crystallin/argininosuccinate lyase (ASL), a major enzyme-crystallin of the embryonic lens, is encoded by two similar, tandemly arranged genes (delta 1 and delta 2). We show here by the polymerase chain reaction (PCR) and in situ hybridization that although the amount of mRNA for each of the delta-crystallins increases in the lens epithelial and fiber cells during development of the embryonic chicken, the delta 1 mRNA accumulates preferentially in the fiber cells. The delta 1/delta 2 mRNA ratio actually decreased from 16.5 +/- 7 to 6.5 +/- 1 in the central epithelial cells while it increased from 20 +/- 10 to 95 +/- 5 in the fibers between 6 and 14 days of development. By contrast, the heart and brain of 4- to 8-day-old embryonic chickens showed 10(3) to 10(4) times less delta-crystallin mRNA per microgram of total RNA than the lens, with a delta 1/delta 2 mRNA ratio of only 0.20 to 0.30. The tissue-specific differences in the relative expression of the two delta-crystallin genes suggest that the delta 2 polypeptide is principally responsible for ASL activity and that the delta 1 polypeptide is specialized for lens transparency. The trace amounts of delta 1 mRNA in the heart and brain raise the possibility that the delta 1 polypeptide contributes to or modulates ASL activity of the native tetrameric protein. Transfection experiments in which we used the pSVOCAT plasmid demonstrated that both delta-crystallin genes contain an enhancer in their third intron. The promoter and enhancer of each delta-crystallin gene were functionally comparable in the pSVOCAT plasmid when tested in primary embryonic lens epithelial cells, suggesting that the differential expression of the two delta-crystallin genes in the lens requires additional cis-regulatory sequences, post-transcriptional mechanisms, or both.

Macrophage products IL-1 alpha, TNF alpha and bFGF may mediate multiple cytopathic effects in the developing eyes of GM-CSF transgenic mice

GM-CSF transgenic mice develop eye disease during ontogeny that is mediated by autostimulated macrophages. The ocular pathology is characterized in part by corneal and vitreous neovascularization, pronounced GFAP expression by retinal Müller cells and degeneration of the retinal photoreceptor layer. The invading intraocular macrophages express the genes for the cytokines interleukin-1 alpha, tumor necrosis factor alpha and basic fibroblast growth factor, which may contribute to the multifaceted developmental ocular disorder. These cytokines, suspected to be angiogenic, may be responsible for neovascularization of the cornea in our transgenic animals. GFAP is normally made by astrocytes in the superficial retina and is induced in Müller cells in models of retinal degeneration. This protein is abnormally and copiously produced by Müller cells in the transgenic mice, which we suggest may be due to the release of cytokines from the invading macrophages. We suggest a mechanism by which autostimulated macrophages, through a perturbation of their normal developmental role, may be responsible for photoreceptor cell death in these transgenic animals.

Postimplantation whole embryo culture: a new method for studying ocular development

The molecular events involved in normal and abnormal eye development are of pivotal importance, but the living mammalian embryo during organogenesis is virtually inaccessible to the investigator. We describe a method of whole embryo culture applicable both to rat and to mouse. With these techniques, embryos in vitro develop normally through the crucial period of organogenesis, which includes early eye development. This method will enable us to manipulate the milieu in which the embryo develops, and so enable us to study the role of growth factors and other molecules in this important but hitherto inaccessible stage of ocular ontogeny.

Chronic diabetes harms islet-cell transplants by inhibiting graft vascularisation

Pancreatic islet-cell transplantation is very effective in treating insulin-dependent diabetes in animals but has had no success in humans. Most animals have received islet-cell grafts after short periods of diabetes, while patients have been grafted after years of disease. We have shown a detrimental effect of chronic diabetes on islet-cell grafts in animals, which is at least partially ameliorated by peritransplant insulin infusion. We suggest that this detrimental effect may be mediated by poor vascularisation. There is further evidence from wound healing and tumour grafting experiments, and from the recent insulin pump studies in humans to support our hypothesis. To be successful, islet-cell grafts in humans may have to be performed earlier in the course of the disease and be preceded by a period of accurate diabetic control.

Insulin-like growth factor II may play a local role in the regulation of ocular size

The ultimate size and shape of the eye has a profound influence on its refraction and function. However, the role of growth factors in normal ocular development is poorly understood. Insulin-like growth factors IGF-I and -II have major effects on cell growth and differentiation in tissue culture. Recently their importance for in vivo development has been studied; IGF-II is predominant prenatally, with a probable local role in the differentiation of some mesodermally derived tissues. Ocular development and size is partially dictated by the condensation of the outer collagenous scleral coat (the ‘white’) of the eye from orbital mesoderm. We investigated IGF-II expression and IGF-II receptor distribution during normal ocular development in the mouse fetus using in situ hybridization and immunohistochemistry. IGF-II mRNA was expressed by the loose mesenchymal orbital tissue as it differentiated to form the sclera, but not in the compact mature sclera or cornea, or in the ectodermally derived retina or skin. IGF-II gene expression was seen in the orbit at E14, reached a peak just before parturition and then declined to background levels after birth. Similarly, type 2 IGF receptors were shown with immunohistochemistry to be present on developing scleral cells and to be modulated in parallel with IGF-II mRNA expression. We suggest the IGF-II expression by differentiating cells that compact to form the collagenous ocular coat plays a local role in determining the ultimate shape and size of the developing eye.

Difference in effect of cultured fetal pancreas transplants on retinal and renal capillary basement membrane thickness in diabetic mice

The goal of endocrine pancreas transplants should be the prevention of diabetic complications. The differential effect of grafts of organ-cultured fetal mouse pancreas on diabetic complications in the retina and kidney was tested by comparing capillary basement membrane thickness (BMT) in mice made diabetic with streptozotocin and transplanted either early or late, or treated with insulin. BALB/c female mice were grafted with a single organ-cultured syngeneic fetal pancreas at either 3 weeks or 7 months after induction of diabetes. Controls were sex- and age-matched nondiabetic; diabetic untreated; and diabetic insulin-treated mice. All mice were killed at 20 months of age and their eyes and kidneys fixed for electron microscopy. BMT was measured on coded micrographs. In all mice glomerular capillary BM were thicker than retinal capillary BM. Mice grafted early after the induction of diabetes had normal BMT in both sites, while those transplanted after 6 months of disease had normal retinal, but thickened glomerular, capillary BM. In each case the late-transplanted animals had BM thickness significantly less than the insulin-treated or untreated diabetics.

Developmental ocular disease in GM-CSF transgenic mice is mediated by autostimulated macrophages

The eyes of transgenic mice aberrantly expressing the murine granulocyte-macrophage colony-stimulating factor (GM-CSF) gene contain an additional population of phagocytic cells which perturb ocular development. Immunohistochemical analysis shows that these phagocytic cells bear macrophage-specific surface antigens, while hybridization histochemical and transcription analyses indicate that they also express the GM-CSF transgene. Macrophages play a physiological role in the developing mammalian eye, in the removal of both the temporary hyaloid vasculature in the vitreous and redundant neurons from the retina. The onset of ocular disease in transgenic mice coincides with this period of remodeling and the onset of transgene expression. In GM-CSF transgenic mice we observed an amplification of the phagocytic response, loss of its tissue-specific and temporal regulation, and resultant damage to normal ocular tissues. We propose that this disease is a consequence of autostimulation of resident intraocular macrophages at a crucial time in ocular development.

Pancreatic islet transplantation ameliorates the effect of diabetes on retinal capillary endothelial cell kinetics

Perturbations in capillary endothelial cell function are early events in the pathogenesis of diabetic retinopathy. We used tritiated thymidine autoradiography to study the turn-over rate of retinal capillary endothelial cells in retinovascular preparations from normal, untreated diabetic and diabetic mice treated with pancreatic islet-cell transplants. Capillary endothelial cell turnover was significantly increased in poorly controlled diabetes and this increase was reduced by islet-cell transplantation. The prevention of excessive endothelial cell replication by tight control of hyperglycemia may help prevent the characteristic structural changes of diabetic microangiopathy, such as basement membrane accumulation.

Transgenic mice expressing a hemopoietic growth factor gene (GM-CSF) develop accumulations of macrophages, blindness, and a fatal syndrome of tissue damage

Transgenic mice carrying the murine granulocyte-macrophage colony stimulating factor (GM-CSF) gene expressed from a retroviral promoter exhibit elevated levels of GM-CSF in the serum, urine, peritoneal cavity, and eye. The eyes of transgenic mice are opaque, contain accumulations of macrophages, and develop retinal damage. Similarly, lesions containing macrophages develop in striated muscle. The mice also display an accumulation of large, often multinucleate, activated macrophages in the peritoneal and pleural cavities. The transgene is transcribed in peritoneal cells, as well as in eyes and infiltrated striated muscle. A high proportion of transgenic mice die with muscle wasting when aged 2-4 months, possibly because of macrophage activation resulting from the high levels of GM-CSF.

Anatomy of the mouse retina. Endothelial cell-pericyte ratio and capillary distribution

A technique is described for preparing whole retinal vascular digests using distilled water and DNase. This produces a more satisfactory preparation of the mouse retinal vascular bed than "trypsin digestion." Nonetheless, the calculation of endothelial cell/pericyte (E/P) ratios based on cell counts from digest preparations has poor reproducibility due to the inability to unequivocally identify at least 25% of the cells in conventionally stained (PAS and hematoxylin) preparations. A more accurate and reproducible means of assessing this ratio uses 1 micron sections of plastic-embedded sections of retina. No effect of age, sex, strain, or area of sampling was found. Capillaries were in three specific bands, centered on the nerve fiber layer, the junction of inner plexiform and inner nuclear layers, and the outer plexiform layers.

Anatomy of the mouse retina. Capillary basement membrane thickness

Transmission electron microscopy of ultrathin sections was used to measure mouse retinal capillary basement membrane thickness (BMT). BMT increases predictably with age from 50 +/- 9 nm at 6 weeks to 154 +/- 27 nm at 20 months, but is not affected by strain or sex. There is an effect of retinal site, however, with BMT increasing with the radial distance from the optic nerve, 41 +/- 4 nm (center), 54 +/- 5 nm (mid-zone), and 64 +/- 6 nm (periphery). The layer of retina from which capillaries were taken had no effect on BMT, and the inner and outer BMT maintained a consistent ratio, even at different ages.

Low-dose immunosuppression may unmask type I diabetes mellitus by specific inactivation of suppressor cells

Type I diabetes mellitus is strongly genetically linked to the major histocompatibility complex but relatively few potentially susceptible people, who are presumably frequently exposed to appropriate triggering factors (e.g. viral illness, environmental agents), develop overt disease. It is possible that some such individuals show latent disease (e.g. islet cell antibodies and perhaps local pancreatic pathology) that does not progress. On the basis of animal data and some clinical evidence we speculate that latent disease is controlled by suppressor cells. We suggest that physiological immunosuppression (e.g. with glucocorticoids) may selectively inactivate such T suppressor cells. Such immunomodulation may allow further islet cell destruction to occur and repeated episodes could eventually produce diabetes. Such episodes of altered immunoregulation may be due to intercurrent viral illness, stress, or therapy with low doses of immunosuppressive agents.

A comparison of portal versus systemic venous drainage in murine foetal pancreatic islet transplantation

We have compared the efficiency of foetal islet graft growth and function in renal subcapsular (systemic drainage) and splenic (portal drainage) sites. Age-matched female BALB/c streptozotocin (STZ)-diabetic mice were grafted either under the left renal capsule or on to the hilar surface of the spleen with one half of a syngeneic 17-day gestation foetal pancreas which had been in organ culture for 2 weeks. Gain in body weight, return to normoglycaemia and to normal glycosylated haemoglobin levels were not significantly different between the two groups. However, when an intraperitoneal arginine challenge was performed the portally grafted mice showed more normal responses than the systemically grafted mice. Although still not normal after the arginine challenge, mean blood glucose values were lower and serum insulin values higher in the spleen grafted animals than in the renal subcapsular graft group. The total amount of insulin was assayed by extraction of both the graft and the pancreas of each animal. The amount of insulin in the grafts from the spleen was not significantly different from those in the renal subcapsular site. We conclude that the efficiency of a graft draining into the portal circulation is greater than an equivalent sized graft draining systemically when a maximal challenge is applied.

Duchenne de Boulogne and clinical photography

In an absorbing monograph entitled Mécanisme de la physionomie humaine, Duchenne de Boulogne proposed that each emotion has its own specific facial muscle. Employing the most recent and exciting technical inventions of the mid nineteenth century, Duchenne used faradism to stimulate the facial muscles and photography to record their actions. Using electrical stimulation, he virtually dissected by this novel method the sheets of facial musculature into a number of emotional entities. By masking the stimulated area, he proved that no reflex activity occurs elsewhere in the face--an illusion hitherto accepted almost universally. Classical sculpture which purported to show a specific emotion was resculpted by Duchenne de Boulogne to show the proper use of the specific facial muscles for that emotion. The concept of emotional expression as a basis for muscle classification in the face is shown to be stimulatingly original, although not entirely valid as a scientific basis for physiological research. But the great individualist Duchenne ventured into yet another area. The first use of photography to illustrate clinical cases was in the middle of the nineteenth century. In 1862 Duchenne de Boulogne published two albums of photographs with accompanying text which appear to have been the first publicly published volumes using photographs of clinical material. The Album de photographies pathologiques contained photographs of clinical entities later linked eponymously with Duchenne, while the Mécanisme de la physionomie humaine presented scores of original prints, some including Duchenne himself in photograph.