Abstract: Objective To construct a mouse model of Pneumocystis pneumonia ( PCP) and evaluate the immunological characteristics of the model mice. Methods A PCP model was established by endotracheal infusion of Pneumocystis murine into severe combined immune deficiency mice. The etiology was identified by quantitative real-time PCR and silver hexaammonium staining of lung tissue. The degree of lung tissue injury was assessed by HE staining, and immunological evaluation was performed by immunofluorescence staining and flow cytometry. Results After six weeks of P. murina infection, there were significantly more lung tissue rRNA copies from P. murina in the experimental group than the sham group. P. murina trophozoites and cysts were detected in lung tissue sections from mice in the experimental group by silver hexaammonium staining. HE staining showed the alveolar walls of lung tissues in the experimental group were thickened, the lung interstitium was widened, and a large number ofGr-1⁺ neutrophils andCD68⁺ macrophages had infiltrated the lungs. The levels of myeloperoxidase, a marker of neutrophil activation, and nitric oxide synthase, a marker of macrophage activation, were significantly increased. Flow cytometry showed that the number and proportion of neutrophils and monocytes in the lungs and alveolar lavage fluid were significantly higher in the experimental group than the control and sham groups. Conclusions A stable PCP mouse model was established by endotracheal infusion of P. murina into SCID mice, which showed immunological characteristics similar to clinical signs.

Abstract: Objective To achieve the efficient isolation of mouse bone marrow mesenchymal stem cells (mBMSCs). Methods mBMSCs from C57BL/6 mice, aged 7 to 9 weeks, were isolated by four method: the bone fragment digestion and crawl method, whole-bone-marrow adherent method, bone fragment digestive fluid supernatant method, and bone fragment digestion and mortar method. An inverted microscope was used to observe the morphology of the mBMSCs, and their characteristic immunophenotype was detected by flow cytometry. The osteogenic and adipogenic differentiation abilities of mBMSCs were detected through multidirectional differentiation induction. Results Isolated primary cells were observed under an inverted microscope after the first fluid change. A large number of bone fragments and miscellaneous cells only were found in the primary cells isolated by the bone fragment digestion and crawl method, and this method was no longer evaluated. Only a small number of polygonal adherent cells and a large number of miscellaneous cells were observed in the whole-bone-marrow adherent-extracted sample. The cells isolated by the bone fragment digestive fluid supernatant method were longer spindle-shaped and triangular adherent cells, but there were many miscellaneous cells. The cells isolated by the bone fragment digestion and mortar method were longer spindle-shaped and polygonal adherent cells, and there were fewer miscellaneous cells. The isolated cells were cultured to passage 3, and the characteristic immunophenotypes of mBMSCs were analyzed by flow cytometry. The result showed that the purity of mBMSCs isolated via the bone fragment digestive fluid supernatant method and bone fragment digestion and mortar method was higher than that of cells isolated via the whole-bone-marrow adherent method. When osteogenic differentiation and adipogenic differentiation were induced, cells isolated by the bone fragment digestive fluid supernatant method and bone fragment digestion and mortar method had stronger multidirectional differentiation potential than those isolated with the whole-bone-marrow adherent method. Conclusions mBMSCs isolated using the bone fragment digestive fluid supernatant method and the bone fragments digestion and mortar method were of higher purity and quality than those from the other method.

Abstract: Objective This study aimed to test the efficacy of an ethanolic extract of Polygonum cuspidatum(PCE) against adenine-induced renal interstitial fibrosis (RIF) in C57BL/6N mice and reveal its underlying molecular mechanisms of action. Methods An RIF model was induced by gavaging C57BL/6N mice with adenine. Fifty male C57BL/6N mice were randomly divided into five groups (n=10 per group): normal control group, model group, PCE-L, PCE-M and PCE-H (75, 150, 300 mg/ kg, respectively) groups. After treatment for 42 consecutive days, serum creatinine (Scr) and blood urea nitrogen (BUN) levels were measured with commercially purchased kits. Histopathological changes to the kidneys were assessed by HE and Masson staining. The protein expression levels of TGF-β1, Smad6, α-SMA, and type I collagen (Collagen I) in kidney tissue were detected by Western Blot. Results Compared with the normal control group, the model group had significantly increased BUN and Scr (P<0. 01). The protein expression level of TGF-β1 was significantly increased (P< 0. 01), while Smad6, a negative regulator of the TGF-β/ Smad pathway, was significantly downregulated (P< 0. 01). The expression of the epithelial-mesenchymal transformation (EMT) marker protein α-SMA and the extracellular matrix (ECM) protein Collagen I were significantly increased (P< 0. 01). Compared with the model group, the drug intervention groups showed decreased levels of BUN and Scr; declining protein expression levels of TGF-β1, α-SMA and Collagen I; increased levels of Smad6 protein; and the alleviation of pathological changes. Conclusions PCE treatment attenuated adenine-induced renal impairment and ameliorated renal interstitial fibrosis in mice. The mechanism of action may be related to changes to the TGF-β1/ Smad signaling pathway and the suppression of EMT and ECM protein deposition.

Abstract: Objective To investigate the effect of bone marrow mesenchymal stem cells (BMSCs) on rheumatoid arthritis and secondary bone loss in a spontaneous rheumatoid arthritis mouse model (Tg-huTNFα mice). Methods 3-week-old Tg-huTNFα mice were divided into three groups: ( 1) Model group: 0. 1 mL/10 g normal saline was intraperitoneally injected once a week; (2) huTNFα antibody intervention group (Anti-huTNFα): 10 mg/ kg Anti-huTNFα was intraperitoneally injected once a week; (3) BMSC intervention group (BMSCs): 5 × 10⁶ BMSCs were injected into both knee joint cavities once a week. During the intervention period, the animals were weighed once a week, and ankle joint health was scored clinically. The animals were killed after 10 weeks of intervention. The percentages of T cells, B cells and CD4⁺ / CD8⁺ T cells in the peripheral blood were analyzed by flow cytometry. The amounts of huTNFα, IL-4 and IL-1β in peripheral blood serum were detected by liquid chip technique. Pathological changes to the left knee joint and ankle joint were evaluated by HE staining, and the right femur bone structure was analyzed by bone histomorphometry. Results BMSCs and Anti-huTNFα provided relief from weight loss in Tg-huTNFα mice; inhibited joint swelling and deformation; and reduced the peripheral blood huTNFα content, joint pathology score, and extent of joint synovium and cartilage damage. Additionally, BMSCs improved the trabecular bone number and percentage trabecular bone area to different degrees and improved the femur bone structure in Tg-huTNFα mice. Conclusions Injection of BMSCs into the joint cavity significantly alleviated symptoms of rheumatoid arthritis in Tg-huTNFα mice, improved femur bone structure, and alleviated bone loss secondary to RA.

Abstract: Objective To establish a model of fungal otitis media induced by Candida albicans and provide a useful animal model for drug efficacy evaluation. Methods Fifty healthy adult SD rats (50% male and 50% female) were randomly divided into a normal control group, blank injection group, moist group, immunosuppressive group, and moist immunosuppressive group, with 10 rats in each group. During the first 1 ~ 3 days of the experiment, a 0. 9% sodium chloride injection was administered twice daily to the right ears of the rats in the moist group, 0. 81 mg/ kg dexamethasone acetate was given daily by oral gavage to the immunosuppressive group, and 0. 81 mg/ kg dexamethasone acetate along with 0. 9% sodium chloride injection by oral gavage was given twice daily into the right ear of the rats in the moist immunosuppressive group. On day 4, after the animals in each group were anesthetized with diethyl ether, the moist, immunosuppressive, and moist immunosuppressive groups were injected with 1 × 1010 CFU/ mL C. albicans solution (50 μL to each rat), the blank group was injected with an equal volume of saline, the blank injection group was injected with an equal volume of blank culture solution, and the normal control group was given no treatment. Subsequently, a 0. 9% sodium chloride injection was administered twice daily to the right ears of rats in the moist and moist immunosuppressive groups. During the model-creation period, the general state of the rats in each group was observed. On the 5th, 10th, and 15th days of modeling, ear canal secretions were collected for C. albicans culture and Gram stain counting. On the 15th day of modeling, ELISA was used to detect interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and interleukin-β (IL-β) in ear canal irrigation samples. HE staining was performed to observe pathological changes to the lung and middle ear tissues, and bacterial culture counts were performed. Results Compared with the blank injection group, the moist, immunosuppressive, and moist immunosuppressive groups all showed different degrees of otitis media symptoms, and the levels of IL-6, TNF-α, and IL-1β were significantly increased (P< 0. 05, P< 0. 01), with different degrees of mucosal congestion, edema, and inflammatory cell infiltration in the middle ear. The number of C. albicans in the ear canal secretions of rats was significantly increased in both the immunosuppressive and moist immunosuppressive groups (P< 0. 05, P< 0. 01). Conclusions In this experiment, C. albicans was injected into the middle ear of rats through a tympanic membrane puncture to establish a model of fungal otitis media. The most effective model creation was under moist immunosuppressive conditions, and this model can be used to evaluate the effects of drugs.

Abstract: Objective To investigate the toxic effects of acrylamide (ACR) on the lung tissue of mice and its possible mechanism of action. Methods 4-week-old SPF male mice were randomly divided into a control and two ACR groups (10 mg/ (kg·d)group and 20 mg/ (kg·d)group), with eight mice in each group. The control group was given conventional drinking water. In the ACR groups, the exposure concentration of ACR was prepared according to 5 mL of drinking water per day which was changed every 3 days for 4 weeks. At the end of the experiment, lung tissue was sectioned for histopathological analysis. Related indexes of oxidative damage were detected. Immunofluorescence and Western Blot were used to detect the expression of Nrf2-ARE-pathway-related proteins. Results Compared with the control group, the body weight of mice decreased gradually with an increase in ACR concentration (P< 0. 01). Histopathological analysis showed that bronchiolar epithelial hypertrophy, alveolar epithelial hyperplasia, and the alveolar cavity area were significantly reduced in the ACR group, and the pathological changes were more obvious in the 20 mg/ (kg·d) group. Compared with the control group, the activity of GSH-Px (P< 0. 05), SOD (P< 0. 05), and CAT (P< 0. 01) in lung tissue decreased with an increase in ACR concentration, while the content of MDA increased significantly (P< 0. 01). Immunofluorescence result showed that, compared with the control group, the ACR group’s expression of Nrf2 protein in the lung tissue was significantly increased, and the highest expression was found in the 10 mg/ (kg·d)group (P< 0. 001). The nuclear translocation phenomenon occurred, and expression of the chaperone protein Keap1 was significantly decreased, with the lowest expression found in the 10 mg/ (kg·d)group (P< 0. 001). Western Blot result showed that, compared with the normal control group, expression of the Nrf2 gene and its downstream antioxidant protein HO-1 was increased in the lung tissue of the ACR group, and the highest level was found in the 10 mg/ (kg·d) (P< 0. 01). Expression of the chaperone protein Keap1 was significantly decreased, and the lowest expression was found in 10 mg/ (kg·d)group (P< 0. 01), but the expression of NQO-1 gradually increased with increased ACR intake concentration (P< 0. 01). Conclusions Exposure of adolescent mice to ACR can lead to lung tissue injury, which may be related to a redoxic imbalance of the lung tissue.

Abstract: Objective To establish a rat model of chronic obstructive pulmonary disease (COPD) with phlegmdampness syndrome. The metabolic characteristics of this rat model were revealed using metabolomics technology. Methods A rat model of COPD with phlegm-dampness syndrome was established by forced smoking combined with LPS airway infusion, forced swimming, and alternate-day fasting. The rat model was evaluated by observing behavioral changes; measuring the body weight, anal temperature, blood indexes, and IL-6, IL-1β, and TNF-α contents; and observing tissues histopathological changes. Differential plasma metabolites between the normal group and the model group were detected and screened by liquid chromatography-mass spectrometry, and enrichment analysis was conducted for metabolic pathways. Results Compared with the normal group, COPD rats with phlegm-dampness syndrome showed different severities of symptoms, including coughing, wheezing, depression, fatigue, withered and dry hair color, weight loss, increased water intake, increased body temperature, production of loose feces containing fat, and a white and smooth tongue coating. In the model rat, the number of white blood cells and lymphocytes in the peripheral blood and the contents of IL-6, IL-1β, and TNF-α in the BALF significantly increased. In the lung tissue, there was obvious inflammatory cell infiltration; the alveolar lumens appeared as different sizes; and the mucous membranes of the colon, duodenum, and ileum were partially exfoliated. There were 116 metabolites that differed between the normal group and COPD group with phlegm-dampness syndrome. These metabolites mainly involved metabolic pathways, including amino acid biosynthesis and metabolism; vitamin digestion, absorption, and metabolism; lipid and lipoid biosynthesis and metabolism; and other metabolic pathways. Conclusions This study provides an effective method for establishing a rat model of COPD with phlegmdampness syndrome and a corresponding evaluation system and has preliminarily revealed the main metabolic characteristics of this rat model.

Abstract: Objective By studying the effects of different modeling cycles on related indicators in a hydroxyureainduced kidney-yang deficiency animal model, the optimal modeling time was obtained. The stability of the model was evaluated. We provide method for creating a stable animal model of warming and tonifying kidney-yang to treat yangdeficiency syndrome. Methods Rats were gavaged with 30 mg/ mL hydroxyurea suspension (300 mg/ kg body weight) once daily for 28 days. On the 7^th, 14^th, 21^st, and 28^th days of gavage, the general condition, biochemical indexes related to kidney-yang deficiency, and the morphology of the internal organs were examined to determine the optimal modeling cycle. Results On the 7^th day of hydroxyurea gavage, the energy metabolism of rats with kidney-yang deficiency induced by hydroxyurea was assessed, and their body temperature, activity of kidney Na⁺ -K⁺ -ATPase, serum content of cAMP, and cAMP/ cGMP ratio were significantly decreased ( P< 0. 05). There were no significant changes in the rats’ neuroendocrine systems, immune functions, or urogenital systems. On the 14^th day of hydroxyurea administration, serum cGMP increased significantly (P< 0. 05) and total ATPase activity decreased significantly (P< 0. 05). There were no significant changes in the temperature of the extremities or tails of the rats or kidney Ca²⁺ -Mg²⁺ -ATPase activity (P> 0. 05). Levels of the neuroendocrine system indicators serum T and T4 were significantly decreased (P< 0. 05). In the urogenital system, there were structural pathological changes to the kidney and testis, and the kidney index decreased significantly (P> 0. 05). On the 21^st day of hydroxyurea gavage, the temperature of the extremities and tails of rats and the kidney activity of Ca²⁺ -Mg²⁺ -ATPase were significantly decreased (P< 0. 05). The neuroendocrine system indicators urine 17-OH-CS and serum T3 levels were significantly decreased (P< 0. 05). On the 28^th day of hydroxyurea gavage, the immune function indicator, the spleen index, decreased significantly (P< 0. 05), and thymus pathological changes were significant and irreversible. In the urogenital system, pathological changes to the kidney and testis were significant and irreversible. Energy metabolism, neuroendocrine system, immune function, and urogenital system indexes still showed decreasing trends on day 28, but there were no significant differences in energy metabolism, neuroendocrine system, or urogenital system indicators compared with on day 21 (P> 0. 05). Conclusions We found significant differences among the modeling time periods for each energy metabolism, neuroendocrine, immune, and urogenital function index, and other aspects, of a hydroxyurea-induced rat model of kidney-yang deficiency. The best modeling time was 28 days.

Abstract: Objective To prepare and evaluate a mouse model of chronic lymphocytic leukemia in order to provide a preclinical model for the treatment of chronic lymphocytic leukemia. Methods The cyclophosphamide (CTX)injection dose was determined after a literature review and experiments to prepare an immunosuppressed mouse model; 1 × 107 MEC-1 cells were transplanted into mice for three consecutive days by intraperitoneal injection and tail vein injection to prepare mice with chronic lymphocytic leukemia. Flow cytometry, immunohistochemistry, and other method were used to detect changes in peripheral blood leukocytes and CD19⁺ CD5⁺ B lymphocytes in mice with chronic lymphocytic leukemia and to analyze the infiltration of MEC-1 cells into the liver, spleen, thymus, lungs, lymph, and bone marrow. Results It was determined that a CTX dose of 150 mg/ kg injected for four days could significantly reduce the immune system function of mice. After transplantation with MEC-1 cells, mice exhibited chronic lymphocytic leukemia(CLL) characteristics. The number of white blood cells and B lymphocytes increased, and bone marrow cells multiplied. Conclusions A CTX dose of 150 mg/ kg injected for four consecutive days significantly reduced the immune function of mice and led to the successful preparation of a mouse model of CLL.

Abstract: Objective To explore the effect and action of remazolam on brain injury caused by sepsis. Methods Male C57BL/6J mice were randomly separated into sham operation, model, remazolam (8 mg/ kg), remazolam + Sirt1 inhibitor (EX527) (8 mg/ kg remazolam + 5 mg/ kg EX527), and EX527 groups by the random number table method, with 38 rats in each group. A sepsis-associated encephalopathy (SAE) mouse model was established by cecal ligation and puncture. After the corresponding intervention was given, the survival rates of mice within seven days after the operation were observed and recorded, and a Morris water maze was used to detect the mice’s escape latency and number of times crossing the platform. Twenty-four hours after surgery, blood-brain barrier (BBB) permeability was assessed by Evans blue (EB) leakage; the levels of interleukin (IL)-6, tumor necrosis factor (TNF)-α, and IL-1β in brain tissue were detected by enzyme-linked immunosorbent assay; the levels of malondialdehyde (MDA) and activities of superoxide dismutase (SOD) and catalase (CAT) in brain tissue were detected by chemical colorimetry. Histopathological changes to the hippocampus were observed by HE staining, and neuronal apoptosis was detected using the TUNEL method. Western Blot was used to detect the expression of silent information regulator 1 (Sirt1) / forkhead box O1 (FoxO1) pathway-related proteins in the hippocampus. Results Compared with the sham group, mice in the model group had a significantly decreased survival rate, platform crossing time, SOD and CAT activities, and Sirt1 and cytoplasmic NF-κB p65 protein levels and significantly increased brain tissue EB content; IL-6, TNF-α, IL-1β, and MDA levels; hippocampal neuron apoptosis index; acetylated FoxO1 (Ac-FoxO1) / FoxO1 ratio; and acetylated nuclear factor-κB p65 (Ac-NF-κB p65) and nuclear NF-κB p65 protein levels (all P< 0. 05). Compared with the model group, mice in the remazolam group had a significantly increased survival rate, platform crossing time, SOD and CAT activities, and Sirt1 and cytoplasmic NF-κB p65 protein levels, and significantly decreased escape latency; brain tissue EB content; IL-6, TNF-α, IL-1β, and MDA levels; hippocampal neuron apoptosis index; Ac-FoxO1/ FoxO1 ratio; and Ac-NF-κB p65 and nuclear NF-κB p65 protein levels (all P< 0. 05). EX527 inhibited the expression of Sirt1 and substantially attenuated the above protective effects of remazolam in SAE mice (all P< 0. 05). Conclusions Remazolam improved the survival rate of mice with sepsis and reduced neuronal apoptosis and brain damage caused by sepsis by maintaining BBB integrity and inhibiting neuroinflammation and oxidative stress. Its mechanism of action may be related to the activation of the Sirt1/ FoxO1 pathway and inhibition of NF-κB activation.

Abstract:Cervical spondylotic radiculopathy (CSR) is a disease caused by cervical facet joint disorder or cervical disc degeneration, which compresses nerve roots. CSR is characterized by radiating pain or numbness in the cervical shoulder and upper limbs innervated by nerve roots and severely affects patients’ quality of life. To further study the etiology, pathogenesis, developmental process, prevention, and drug treatment of the disease, the correct selection and establishment of animal models in line with the clinical characteristics of the disease are crucial. In the writing of this paper, relevant literature reports from China and abroad were consulted. The preparation of CSR animal models is summarized to include simple compression models (vascular forceps clamping method, wire ligation method, L-shaped steel column compression method, silica gel compression method, autologous bone compression method, and nylon fishing line compression method), combined stimulation models (clamping method and chrome intestinal wire compression method, formalin quantitative filter paper stimulation method, and drug-mediated and kinetic imbalance method), and a nonsurgical intervention model (low head flexion fixation method). The preparation of CSR animal models is summarized, and their characteristics, advantages, and disadvantages are analyzed to provide an important reference for those selecting appropriate animal models for preclinical research.

Abstract:Atherosclerosis (AS) is a common pathological basis of cardiovascular and cerebrovascular diseases. Establishing an animal model of AS with the characteristics of blood-stasis toxin syndrome and a standardized evaluation system is an important part of modern cardiovascular and cerebrovascular disease research. This model and system are of great significance to research and development of traditional Chinese medicine for the prevention and treatment of cardiovascular and cerebrovascular diseases and the evaluation of drug efficacy mechanisms. This review summarizes and generalizes the construction and evaluation of animal models of atherosclerotic blood-stasis and toxic syndrome. The review further analyzes the problems existing with current model construction and evaluation to provide a reference for the establishment of standardized animal models.

Abstract:Since the first space flights, the number of hours astronauts spend flying in space has increased. Studies have found that the weightlessness of space causes physiological and psychological changes in astronauts that influence their physical health. To explore the mechanisms of these effects and to identify reasonable countermeasures, it is essential to establish effective experimental animal models for simulating weightlessness and conduct in-depth studies. A successful weightlessness simulation model should mimic the changes that occur to major systems in humans, such as cardiovascular, bone, and muscle, due to weightlessness. This paper provides an overview of the existing ground-based weightlessness simulation models and related research to provide a rational strategy for the evaluation of weightlessness simulation models.

Abstract:With the development of the world economy, people’s lifestyles and dietary structure have changed, and the clinical detection rate of hyperuricemia is increasing year by year. Hyperuricemia has the “ fourth highest” incidence after hypertension, diabetes, and hyperlipidemia, and its incidence rate tends to be higher in younger people. Therefore, the establishment of appropriate animal models is an important step in studying the pathogenesis of hyperuricemia and preventing related diseases. In recent years, extensive literature has been published on the establishment of hyperuricemia models. We consulted the relevant literature from recent years and summarized common animal models; we summarized the method for increasing the source of uric acid, inhibiting the activity of uricase, inhibiting the excretion of uric acid, and other modeling method. This paper provides a reference for the study of drugs related to the treatment and prevention of hyperuricemia and method for the construction of hyperuricemia models.

Abstract:The modified multi-platform method (MMPM) is developed from single-platform and multi-platform method and is mostly used to prepare sleep deprivation (SD) animal models. Compared with single-platform and early multi-platform method, MMPM expands the range of activities that animals partake in and decreases the stress caused by group separation and social isolation. Thus, MMPM can increase the social stability of SD animals. The advantages of MMPM, high simplicity and applicability and low mortality, contribute to the popularity in preparing the animal model of SD in China and other countries. However, many experimental factors affect the modeling effects of MMPM,resulting in uneven modeling effects in different SD studies. In this article, to improve the stability and reproductivity of the experimental SD and provide a reference for further, the specific application and evaluation method of MMPM in SD animal models are reviewed.

Abstract:The United States Department of Agriculture is charged with drawing up the Animal Welfare Act and Animal Welfare Regulations, the only federal laws that regulate the treatment of animals in research, teaching, testing, and exhibition and include animal facilities, vehicles, equipment, or other sites used or intended for use in business. These federal laws govern large and medium-sized animals, such as monkeys, dogs, cats, and rabbits, and include marine mammals, but do not regulate the use of rats and mice, which are commonly used in biomedical laboratories in universities and institutes in the United States. Therefore, the laws do not fully govern the management of laboratory animals in biomedical research institutions. By contrast, the policy on laboratory animal care and use supervised by the United States National Institutes of Health (NIH) and Public Health Service (PHS) fully governs the use of all vertebrate animal species — including laboratory rats and mice — used in biomedical research. This paper gives a brief overview of historical events and information related to United States Animal Welfare Act and Animal Welfare Regulations. It is expected that this research could offer some enlightenment might offer guide the use and management of laboratory animals in China.

Abstract:Federal law and policy on laboratory animal care and use governed by the Public Health Service (PHS) and by the National Institutes of Health (NIH), Department of Health and Human Services in the United States is different from the Federal Laws and Regulations of the Animal Welfare Act supervised by the Animal and Plant Health Inspection Service of the United States Department of Agriculture. Early in 1961, the NIH released the first version of the Guide for Laboratory Animal Facilities and Care. With a series of important revisions implemented from 1960 s to 1990 s, the PHS/ NIH have established two comprehensible systems: the IACUC and the Guide for the Care and Use of Laboratory Animals. The NIH office of Laboratory Animal Welfare is responsible for the general administration and coordination of the PHS-governed federal law and policy system and revises and releases the IACUC handbook, and the Guide for the Care and Use of Laboratory Animals in the United States. Both publications are also widely adopted as administration references in the field of international biomedical research. This review describes the historic evolution of PHS/ NIH Law and Policy on the use of laboratory animals.