In this study, the aim was to achieve high concentration of recombinant human growth hormone (rhGH) production by recombinant Pichia pastoris by investigating the effects of various operation parameters and to determine the suitable peptide ligand sequence that shows affinity and specificity to hGH. In this context, firstly the effect of temperature and Tween-20/80 addition on production and cell growth were investigated. While at T=30 and 32&deg / C, there was no difference, at 27 and 25&deg / C cell growth slowed down and production decreased significantly. The addition of Tween-20/80 in existence of co-substrate sorbitol did not affect the bioprocess while in absence of sorbitol Tween alone did not show the same positive effect on product formation and cell growth. Thereafter at T=30&deg / C, without addition of Tween, three sets of pilot scale bioreactor experiments were performed. In the first set, the effect of methanol feeding rate on bioprocess characteristics were investigated at the specific growth rates of &mu / =0.02, 0.03 and 0.04 h-1. While the highest cell concentration was achieved at &mu / =0.04 h-1, the highest rhGH concentration was achieved at &mu / =0.03 h-1. Secondly, conducting methanol feeding at &mu / =0.03 h-1, pH=5.5 experiment was conducted. The highest cell concentration, 45 g L-1 and maximum rhGH concentration 0.25 g L-1 were achieved at t=18 h of the process. Finally, the effect of batch sorbitol feeding on bioprocess was observed by the addition of 50 g L-1 sorbitol at t=0, 14 and 31 h of the production phase. It was shown that sorbitol addition to the medium increased process duration / hence cells enter stationary phase after a longer production phase. However, the protease concentration continued increasing with respect to time and at the end of the process reached twice the concentration it was obtained with single sorbitol addition case decreasing the rhGH concentration. In selection of the peptide sequence that shows affinity towards hGH, phage display method was conducted. Additionally the sequences from literature and computational design were used as alternatives. The interaction between these peptides and hGH was investigated by isothermal titration calorimetry and surface plasmon resonance.

In this study, regulatory gene effects on recombinant human growth hormone (rhGH) production by Bacillus subtilis were investigated. For this purpose, firstly Bacillus strains, which are deficient in abrB, aprE, degQ, degS, degU, scoC, sinI, sinR, and spo0A genes, were selected according to the regulatory gene network of aprE gene (serine alkaline protease gene of B. subtilis) since due to the degQ promoter and the pre-signal sequence of subC gene cloned in front of the hGH gene, hGH is produced by mimicking the serine alkaline protease synthesis. R-Bacillus strains were constructed by transformation of pMK4::pre(subC)::hGH plasmid to the selected strains. Thereafter, by the laboratory scale experiments, strains having the highest hGH production capacity were determined as scoC, aprE, sinR, and degU knockout strains. Using these strains, fermentation experiments were carried out in pilot-scale bioreactor in defined medium. Effect of pH control was also investigated and the highest cell and hGH concentration was obtained by scoC knockout strain in pH controlled operation as 1.62 kg m-3 and 126 g m-3, respectively. By this strain, the overall product and cell yield on total substrate were found as 16.12 g kg-1 and 0.15 g g-1, respectively. Furthermore, the highest total protease activity was attained by degU knockout strain as 65 U cm-3. On the other hand, maximum total organic acid secretion was determined as 1.31 kg m-3 in aprE knockout strain.

In this study, recombinant human growth hormone (rhGH) production by Pichia pastoris-Mut+ strain was improved by designing feeding strategies which were applied in the production phase of the bioreactor operations. During the bio-reactor experiments the cell growth, sorbitol and methanol consumptions, recom-binant hGH production, alcohol oxidase (AOX) activity, the by-products protease and organic acid concentrations were followed and analyzed. In this context, in the first part of the study, three bioreactor operations were designed and per-formed. In general, the designed strategies are fundamentally based on simulta-neous feeding of the two substrates starting at t=0 h of the production phase, i.e., batch-wise 50 gL-1sorbitol feeding, together with fed-batch methanol feeding with a specific growth rate of &mu / 0=0.03 h-1 or &mu / 0=0.04 h-1, and fed-batch sorbitol feeding with a specific growth rate of &mu / 0=0.025h-1 which was calculated based on the specific consumption rate qS=0.152 g g-1h-1 of sorbitol. Consequently, sorbitol concentration was kept constant at 50 gL-1 within t=0-15h of the production phase / where, sorbitol feeding was terminated at t=15h. Amongst, in the first strategy (SSM1), methanol was fed to the system with the specific growth rate of &mu / 0=0.03 h-1, and the H+ concentration (pH) in the bioreactor was kept constant at pH=5.0. In the second strategy (SSM2), pH was kept constant at 5.5 until t=24h of the induction phase (production phase), thereafter, was reduced to pH= 5.0 / where methanol was fed to the bioreactor with the specific growth rate of &mu / 0=0.03 h-1. In the third strategy (SSM3), methanol was fed with the specific growth rate of &mu / 0=0.04 h-1, and the pH in the bioreactor was kept constant at pH 5.0. The highest rhGH production and cell concentration were achieved in the first strategy SSM1 as CrhGH=640 mg L-1 and CX=105.3 g L-1, and the overall cell and product yields on total substrate were calculated as YX/S =0.21 g g-1 and YCrhGH/S =1.83 mg g-1. In the second part of this study the two-substrates sorbitol and methanol were fed simultaneously in a solution compose of 1.37 mol sorbitol and 6.21 mol methanol in 13.88 mol water, which is named as SM. In this strategy (SM), the two-substrate solution was fed to the medium with the specific growth rate of &mu / 0=0.03 h-1 on sorbitol until t=30h / thereafter, only methanol was fed to the bio-reactor with the specific growth rate of &mu / 0=0.03 h-1. The highest cell and rhGH concentrations obtained in SM were, respectively, Cx=104.7 g L-1 and CrhGH=124 mg L-1 / and the overall cell and product yields on the total substrate were calcu-lated as YX/S=0.21 g g-1 and YCrhGH/S=0.39 mg g-1. Although the highest cell con-centration obtained at SM is close to that of the SSM1, the rhGH concentration obtained at SM is 5.2-fold lower than that of the strategy SSM1.

Over the past couple of years there has been rapid progress in the development and design of safe and effective delivery systems for the administration of protein and peptide drugs. The effective delivery of these type of drugs are not always as simple as one may think, due to various inherent characteristics of these compounds. Due to the hydrophilic nature and molecular size of peptide and protein drugs, such as recombinant human growth hormone, they are poorly absorbed across mucosal epithelia, both transcellularly and paracellularly. This problem can be overcome by the inclusion of absorption enhancers in peptide and protein drug formulations but this is not necessarily the best method to follow. This investigation focussed specifically on the evaluation of the ability of the PheroidTM carrier system to transport recombinant human growth hormone across mucosal epithelia especially when administered via the nasal cavity. The PheroidTM delivery system is a patented system consisting of a unique submicron emulsion type formulation. The PheroidTM delivery system, based on PheroidTM technology, will for ease of reading be called Pheroid(s) only throughout the rest of this dissertation. The Pheroid carrier system is a unique microcolloidal drug delivery system. A Pheroid is a stable structure within a novel therapeutic system which can be manipulated in terms of morphology, structure, size and function. Pheroids consist mainly of plant and essential fatty acids and can entrap, transport and deliver pharmacologically active compounds and other useful substances to the desired site of action. The specific objectives of this study can be summarised as follows: a literature study on Pheroid technology; a literature study on chitosan and N-trimethyl chitosan chloride; a literature study on recombinant human growth hormone (somatropin); a literature study on nasal drug administration; formulation of a suitable Pheroid carrier; entrapment of somatropin in the Pheroid carrier, and in vivo evaluation of nasal absorption of somatropin in Sprague-Dawley rats. / Thesis (M.Sc. (Pharmaceutics))--North-West University, Potchefstroom Campus, 2007.

Conselho Nacional de Desenvolvimento Científico e Tecnológico / Erythropoietin (EPO) is a glycoprotein which stimulates the erythropoiesis (production of hemaceas) and is clinically used for the treatment of renal anemia. EPO formulations present usually elevated contamination by aluminum. Aluminum is known to participate in the pathogenesis of osteodystrophy and encephalopathy associated with chronic hemodialysis, and has been proposed to be involved in central nervous system degeneration diseases such as Alzheimer s diseases. In the present work, the presence of Al as contaminant in erythropoietin formulations consumed by chronic renal patients, was investigated by developing and optimizing a chromatographic method for separation and determination of proteins, with subsequent collection of fractions and measured of the Al present by graphite furnace atomic absorption spectrometry (GF AAS). As the commercialization of pharmaceutical forms of EPO are in glass containers with rubber cap (bottle, vial or syringe), it was investigated the ability of the constituents of EPO formulations (salts, amino acids, urea, and mannitol among others) to promote the extraction of aluminum present in both glass and rubber. The tests were performed considering the process of sterilization and the contact of the solutions during storage. The results demonstrated that the interaction of EPO with aluminum is higher than that of albumin (the other proteic constituent). Among the other constituents, citric acid and citrate presented the highest interaction. For each constituent there is probably a different mechanism for the release of aluminum from glass and rubber, but all constituent of EPO formulations interacted with glass and rubber packaging, leading to their contamination by aluminum. As the level of contamination by aluminum in commercial formulations of erythropoietin was determined, and it was observed that the lyophilized powder presented the lowest contamination by aluminum, this form must be the choice for renal patients, due to the susceptibility of these patients to aluminum toxicity. / A eritropoetina (EPO) é uma glicoproteína que estimula a eritropoiese (produção das hemáceas) e é usada clinicamente para o tratamento de anemias associadas à insuficiência renal crônica. Formulações de eritropoetina apresentam geralmente uma elevada contaminação por alumínio, que é um metal extremamente tóxico para pacientes com insuficiência renal. Este metal é relacionado a doenças neurológicas e ao comprometimento da estrutura óssea dos pacientes, podendo causar a morte se administrado cronicamente ou em concentrações elevadas aos pacientes. Alguns autores também relacionam o desenvolvimento de doenças degenerativas como a doença de Alzheimer com intoxicação por alumínio. A presença do alumínio em formulações farmacêuticas destinadas ao tratamento da insuficiência renal e nutrição parenteral é um problema sério devido a toxicidade do alumínio e ao contato direto com o sangue do paciente. Em nosso laboratório, nos dedicamos a estudar a origem do aluminio nestas soluções e de que modo ele interage com os seus constituintes. No presente trabalho, investigou-se a presença de Al como contaminante em formulações farmacêuticas de eritropoetina consumida por pacientes renais crônicos através do desenvolvimento e otimização de um método cromatográfico para separação e determinação de proteínas, com posterior coleta de frações e medidas do Al presente por espectrometria de absorção atômica com forno de grafite (GF AAS). Como as formas farmacêuticas de comercialização da EPO são em recipientes de vidro com tampa de borracha (frasco-ampola ou seringas), investigou-se a capacidade dos constituintes das formulações de EPO (sais, aminoácidos, uréia e manitol entre outros) em promover a extração do alumínio presente tanto no vidro quanto na borracha. Os ensaios foram realizados considerando o processo de esterilização e o contato das soluções durante o período de armazenamento. Os resultados encontrados demonstraram que a EPO apresenta maior interação com o alumínio que a albumina (o outro constituinte proteico das formulações). Entre os outros constituintes, o ácido cítrico e o citrato apresentaram a maior interação. Para cada constituinte há provavelmente um mecanismo diferenciado de liberação de Al do vidro e da borracha, porém todos os constituintes das formulações de EPO interagiram com o vidro e a borracha, levando a contaminação destas por alumínio. Como foi determinado o nível de contaminação por alumínio das formulações de eritropoetina comerciais, observou-se que a forma farmacêutica de pó liofilizado apresentou menor contaminação por alumínio devendo, portanto, ser a forma de escolha para os pacientes renais, tão sucetíveis a toxicidade do alumínio.

Effective management of acute pancreatitis has for centuries eluded mankind. The disease has a wide spectrum of presentation; the milder form is usually a self limiting condition, whereas the severe form presents as a highly morbid and frequently lethal attack. The ability to predict disease progression on admission would aid in the comprehensive and multidisciplinary management of patients. The perfect predictor of disease progression has been an elusive factor hindering the management of the disease. On systematically reviewing literature and identifying appropriate biochemical markers in predicting progression of acute pancreatitis, the ideal predictor would be a combination of biochemical, clinical and contemporary organ dysfunction scoring systems. Early prediction of disease progression however, is important in the better management of the disease. The pathophysiological changes of acinar cell injury and death are the earliest events that occur in acute pancreatitis. Identification of potential pharmacological interventions offered through valuable insight in to experimental and clinical acute pancreatitis may lead on to the development of various natural and synthetic potential disease modifiers. Green Tea Extracts (GTE) consumed in many parts of the world has been examined as a potential therapeutic medication. Experimental results have demonstrated the effect of GTE on the oxidative pathway significantly ameliorating the effects of pancreatic injury. The various green tea catechins especially Epigallocatechin-3- gallate (EGCG) can perhaps be useful lead compounds for new drug discovery. With no specific targeted therapy for severe acute pancreatitis at present, various medications have been tested. The possibility of targeting initial acinar cell injury may not be a feasible option as patient presentation and management would usually be after this phase. As the disease progresses, severe acute pancreatitis is characterised by inflammation and necrosis. The hypothesis of preserving pancreatic parenchymal microvascular patency and thus ameliorating pancreatic injury through the early administration of recombinant human Activated Protein C (rhAPC) has identified a potential treatment for acute pancreatitis. rhAPC converted from its inactive precursor, protein C, by thrombin acts through fibrinolysis and inhibition of thrombosis. Studies on rhAPC in experimental acute pancreatitis examined the modulation of rhAPC on inflammatory markers, morphology, microvascular thrombosis and apoptosis. The encouraging results from initial experimental work helped set up the Phase 2 clinical trial of administering rhAPC early on in severe acute pancreatitis. Prior to taking this significant step from bench to bed side, the variation in functional protein C levels with the severity of the disease was examined as a precursor to the Phase 2 trial.

Polychlorinated biphenyls (PCBs) continue to pose a health concern because of their predominance in the diet and air as well as in environmental samples and humans. PCB congeners with 3 or 4 chlorine substituents in ortho position have been associated with neurodevelopmental disorders. Hydroxylated metabolites (OH-PCBs) of these PCBs are also potentially toxic to the developing brain. Metabolism studies have mainly focused on animal models. However, preliminary data from this dissertation work have revealed PCB metabolism differences between laboratory animal models and humans in terms of metabolite profiles, chiral signatures. More concerning, biotransformation of chiral PCBs is poorly investigated in humans. The objective of this dissertation research was to study the biotransformation of chiral and prochiral PCBs to chiral hydroxylated metabolites in humans and rats and to identify individual human P450 enzymes involved in the metabolism of these PCBs. I chose chiral PCB congeners 2,2',3,4',6-pentachlorobiphenyl (PCB 91); 2,2',3,5',6-pentachlorobiphenyl (PCB 95), 2,2',3,3',4,6'-hexachlorobiphenyl (PCB 132) and 2,2',3,3',6,6'-hexachlorobiphenyl (PCB 136) for this investigation because they are environmentally relevant and their metabolism has been studied in rodents and other laboratory animal species (Kania-Korwel et al., 2016a). Prochiral PCB congeners 2,2′,4,6′-tetrachlorobiphenyl (PCB 51) and 2,2′,4,5,6′-pentachlorobiphenyl (PCB 102) were selected because their considerable presence in technical PCB mixtures. To test the hypothesis that P450 enzyme and species differences mediate the congener-specific enantioselective metabolism of chiral PCBs to hydroxylated metabolites, I sought to establish structure-metabolism relationships by studying the enantioselective metabolism of structurally diverse chiral PCBs by human liver microsomes (HLMs). Racemic PCB 91, PCB 95 and PCB 132 were incubated in vitro with pooled or individual donor HLMs at 37 °C, and levels and chiral signatures of the parent PCB and its hydroxylated metabolites were determined by high-resolution gas chromatography equipped with time-of-flight mass spectrometry (GC/TOF-MS) or electron capture detection (GC-ECD). Hydroxylated metabolites formed were identified and metabolic schemes for these PCBs proposed. I found inter-individual differences in the formation of OH-PCBs by individual donor HLMs. Comparison of the metabolite profiles of PCB 91, PCB 95, PCB 132 and PCB 136 (PCB 136 metabolism by HLMs was investigated by other researchers) revealed congener-specific differences in the oxidation of PCBs by human cytochrome P450 enzymes. PCB 91 and PCB 132 were mainly hydroxylated in meta position, with the 1,2-shift metabolites being the major metabolites formed from both PCB congeners by HLMs. In contrast, PCB 95 and PCB 136 were primarily hydroxylated in the para position. Moreover, we determined human P450 isoforms involved in the metabolism of neurotoxic PCBs using in silico and in vitro approaches. In silico predictions suggested that chiral PCBs are metabolized by CYP1A2, CYP2A6, CYP2B6, CYP2E1, and CYP3A4. Experimentally we found that CYP2A6, CYP2B6 and to a minor extent CYP2E1 were the enzymes involved in the metabolism of these chiral PCBS. We also investigated nonchiral sources of chiral OH-PCBs by studying the P450- and species-dependent biotransformation of prochiral PCB 51 and PCB 102 to chiral OH-PCB metabolites. Prochiral PCB 51 and PCB 102 were incubated with liver microsomes prepared from male Sprague-Dawley rats pretreated with various inducers of P450 enzymes including phenobarbital (PB), dexamethasone (DEX), isoniazid (INH), β-naphthoflavone (BNF), clofibric acid (CFA) or corn oil (CO); and untreated male cynomolgus monkeys, Hartley albino guinea pigs, New Zealand rabbits, golden Syrian hamsters; and untreated female Beagle dogs. PCB 51 and PCB 102 were metabolized to 2,2',4,6'-tetrachlorobiphenyl-3'-ol (OH-PCB 51) and 2,2',4,5,6'-pentachlorobiphenyl-3'-ol (OH-PCB 102), respectively. The formation of both metabolites was P450 isoforms- and species-dependent. Moreover, OH-PCB 51 and OH-PCB 102 were chiral and were formed enantioselectively in all microsomes investigated. Taken together, my findings demonstrate (1) considerable inter-individual variability in the congener-specific metabolism of PCBs to OH-PCBs; (2) the enantioselective formation of OH-PCBs by human CYP2A6, CYP2B6, and CYP2E1; and (3) that chiral PCB metabolites are formed enantioselectively from prochiral PCB congeners. Interestingly, the metabolism of PCBs by CYP2A6 appears to involve arene oxide intermediates, as suggested by the formation of 1,2-shift products as major metabolites of PCB 91 and PCB 132. In contrast, 1,2-shift products are minor PCB metabolites formed in rodents. Therefore extrapolation of hepatic metabolism across species may not be consistent and these differences should be considered in future toxicity and risk assessment studies.

Intracellular calcium is a major determinant of a wide variety of cell functions and thus of organ function. In order to get a clear picture of the intracellular calcium status it is preferable to assess the content of the various intracellular calcium pools as well as the characteristics of the transmembrane calcium movements, Le., the magnitude of the transmembrane Ca2+ flux upon stimulation and the rate of the subsequent return to baseline levels. The first aim of this study was to establish and evaluate the methods in the laboratory. The methods investigated include atomic absorption spectrometry, graphite furnace atomic absorption spectrometry and inductively coupled plasma mass spectrometry for the determination of the total cell calcium content, fluorescence spectrophotometry for the determinations of intracellular free Ca2+ and transmembrane Ca2+ movements and transmission electron microscopy for the localisation of intracellular calcium. The methods eventually identified as feasible included fluorescence spectrophotometry for the determination of intracellular free Ca2+ and transmembrane Ca2+ movements and transmission electron microscopy for the localisation of intracellular calcium. The newly developed fluorescent calcium indicator, fura-PE3, was presently shown to be the most reliable fluorescent indicator for the intracellular free Ca2+ determinations. The best method for the calcium localisation by transmission electron microscopy was an adaptation of the antimonate precipitation technique. The following objectives were set in order to contribute to the knowledge in chronic renal failure; examination of the intracellular free Ca2+ content in the neutrophils of end stage renal failure patients on maintenance haemodialysis treatment, as the result of renal failure, dialysis treatment and medication combined; examination of the characteristics of the transmembrane Ca2+ movements; investigation of the intracellular calcium distribution in the neutrophils; exploration of a possible link between the alterations in intracellular calcium status and factors known to influence the calcium status, including the lipid composition of the membrane, the oxidative status as reflected by anti-oxidant vitamin levels, as well as the levels of parathyroid hormone, and ionised serum calcium. This study involved 14 chronic renal failure patients on maintenance haemodialysis. An increase in intracellular free Ca2+, the magnitude of the transmembrane Ca2+ flux upon fMLP stimulation and an increase in the rate of the subsequent decrease in intracellular free calcium were found. In separating the patients into those receiving rHuEPO and those not receiving rHuEPO, it was seen that the significance in the increase in intracellular free Ca2+ could be ascribed to the values obtained in those patients receiving rHuEPO - despite the fact that they were the only patients receiving calcium channel blockers. No overt indications of oxidative stress could be detected by anti-oxidant vitamin levels. Nevertheless, a decrease in the content of specific membrane fatty acids occurred, supporting the previous suggestions of the presence of a mild chronic inflammatory condition in the chronic renal failure patient on maintenance haemodialysis treatment. These results suggest that factors other than those associated with uraemia, such as rHuEPO administration, might result in an increase in intracellular free Ca2+ in cells of CRF/MHT patients. The magnitude of the rHuEPD-induced increase in intracellular free Ca2+ and the effects of the various calcium channel blockers need urgent further investigation as ineffective counteraction of the rHuEPO effect, as indicated by the relative ineffectivity of Norvasc, may have serious side-effects. / Dissertation (MSc)--University of Pretoria, 2000. / Physiology / unrestricted

Autoimmune neutropenia (AIN) is characterized by antibody mediated peripheral destruction of neutrophils. Since there is no effective treatment, antibiotics have to be used frequently for recurrent infections. Five selected patients with serologically proven AIN were treated with r-metHuG- CSF at 5-8 μg/kg body weight (300-480 μg) daily: the dose and frequency of r-metHuG-CSF was reduced after neutrophil counts above 1.0 x 109/l were obtained. R-metHuG-CSF is effective in AIN and causes a sustained rise in ANC which can he maintained on a low dose administered twice or thrice weekly.

β-Casein is a major milk protein, which is synthesized in mammary alveolar secretory epithelial cells (MECs) upon the stimulation of lactogenic hormones, mainly prolactin and glucocorticoids (HP). Previous studies revealed that the proximal promoter (-258 bp to +7 bp) of the β-casein gene is sufficient for induction of the promoter activity by HP. This proximal region contains the binding sites for the signal transducer and activator of transcription 5 (STAT5), glucocorticoid receptor (GR), and octamer transcription factors (Oct). STAT5 and GR are essential downstream mediators of prolactin and glucocorticoid signaling, respectively. This study investigated the functions of Oct-1 and Oct-2 in HP induction of β-casein gene expression. By transiently transfection experiment, we showed that individual overexpression of Oct-1 and Oct-2 further enhanced HP-induced β-casein promoter activity, respectively, while Oct-1 and Oct-2 knockdown significantly inhibited the HP-induced β-casein promoter activity, respectively. HP rapidly induced the binding of both Oct-1 and Oct-2 to the β-casein promoter, and this induction was not mediated by either increasing their expression or inducing their translocation to the nucleus. In MECs, Oct-2 was found to physically interact with Oct-1 regardless of HP treatment. However, HP induced physical interactions of Oct-1 or Oct-2 with both STAT5 and GR. Although the interaction between Oct-1 and Oct-2 did not synergistically stimulate HP-induced β-casein gene promoter activity, the synergistic effect was observed for the interactions of Oct-1 or Oct-2 with STAT5 and GR. The interactions of Oct-1 with STAT5 and GR enhanced or stabilized the binding of STAT5 and GR to the promoter. Abolishing the interaction between Oct-1 and STAT5 significantly reduced the hormonal induction of β-casein gene transcription. Thus, our study indicates that HP activate β-casein gene expression by inducing the physical interactions of Oct-1 and Oct-2 with STAT5 and GR in mouse MECs. There is a high and increasing demand for insulin because of the rapid increase in diabetes incidence worldwide. However, the current manufacturing capacities can barely meet the increasing global demand for insulin, and the cost of insulin production keeps rising. The mammary glands of dairy animals have been regarded as ideal bioreactors for mass production of therapeutically important human proteins. We tested the feasibility of producing human proinsulin in the milk of transgenic mice. In this study, four lines of transgenic mice were generated to harbor the human insulin gene driven by the goat β-casein gene promoter. The recombinant human proinsulin was detected in the milk by Western blotting and enzyme-linked immunosorbent assay. The highest expression level of human proinsulin was as high as 8.1 μg/µl in milk of transgenic mice at mid-lactation. The expression of the transgene was only detected in the mammary gland during lactation. The transgene expression profile throughout lactation resembled the milk yield curve, with higher expression level at middle lactation and lower expression level at early and late lactation. The blood glucose and insulin levels and major milk compositions of transgenic mice were not changed. The mature insulin derived from the milk proinsulin retained biological activity. Thus, our study indicates that it is practical to produce high levels of human proinsulin in the milk of dairy animals, such as dairy cattle and goat.