Transmission of rat and guineapig Haemophilus spp. to mice and rats

Mice and rats, free from Pasteurellaceae, were exposed to Haemophilus spp. (V-factor dependent Pasteurellaceae) by housing in proximity to infected rats or guinea pigs, and monitored by culture and enzyme-linked immunosorbent assay (ELISA) for cross infection. A minority of mice became infected when exposed to Haemophilus-infected rats but none when exposed to guinea pigs. Rats were readily infected when exposed to Haemophilus-infected guinea pigs or rats. Although Pasteurellaceae infections are commonly considered as host specific, our data show that Haemophilus spp. can cross the species barrier from rats to mice and from guinea pigs to rats.     

The behavioral endocrinology of domestication: A comparison between the domestic guinea pig (Cavia aperea f. porcellus) and its wild ancestor, the cavy (Cavia aperea)

In this study spontaneous behavior and endocrine parameters were compared between the domestic guinea pig (Cavia aperea f. porcellus) and its wild ancestor, the cavy (Cavia aperea), to elucidate the process of domestication in this species. In 120 h of observation time the behavior of five groups of wild and seven groups of domestic guinea pigs, each consisting of one adult male and two adult females, was analyzed quantitatively. To assess the activities of the pituitary-adrenocortical (PAC), the pituitary-gonadal (PG), and the sympathetic-adrenomedullary (SAM) systems, serum cortisol, testosterone, epinephrine, and norepinephrine concentrations, as well as adrenal tyrosine hydroxylase activities, were determined in males of both forms. The following significant differences between wild cavies and domestic guinea pigs were found: the domesticated animals displayed less aggressive but more sociopositive and more male courtship behavior than their wild ancestors. In addition, they were distinctly less attentive to their physical environment than the wild cavies. The basal activity of the SAM system, as well as the reactivity of the SAM and the PAC systems, was distinctly reduced in the domesticated animals. In contrast, the basal activity of the PAC system did not differ between both forms. The activity of the PG system was significantly higher in males of the domestic guinea pig than in male wild cavies. Thus, in guinea pigs the process of domestication has led to typical behavioral traits-reduced aggressiveness, increased social tolerance-which have also been found in comparisons between wild and domestic forms of other species. The decreased reactivity of the organism's stress axes can be regarded as a physiological mechanism which helps domesticated animals to adjust to man-made housing conditions.     

The daily pattern of heart rate, body temperature, locomotor activity, and autonomic nervous activity in congenitally bronchial-hypersensitive (BHS) and bronchial-hyposensitive (BHR) guinea pigs.

We studied the characteristics of the rhythmicity of heart rate (HR), body temperature (BT), locomotor activity (LA) and autonomic nervous activity in bronchial-hypersensitive (BHS) and bronchial-hyposensitive (BHR) guinea pigs. For this purpose, HR, BT, LA, and electrocardiogram (ECG) were recorded from conscious and unrestrained guinea pigs using a telemetry system. Autonomic nervous activity was analyzed by power spectral analysis of heart rate variability. Nocturnal patterns, in which the values in the dark phase (20:00-06:00) were higher than those in the light phase (06:00-20:00), were observed in HR, BT and LA in both strains of guinea pigs. The autonomic nervous activity in BHS guinea pigs showed a daily pattern, although BHR guinea pigs did not show such a rhythmicity. The high frequency (HF) power in BHS guinea pigs was higher than that in BHR guinea pigs throughout the day. Moreover, the low frequency/high frequency (LF/HF) ratio in BHS guinea pigs was lower than that in BHR guinea pigs throughout the day. These results suggest that parasympathetic nervous activity may be predominant in BHS guinea pigs.     

Biochemical basis for the resistance of guinea pigs to carcinogenesis by 2-acetylaminofluorene

Studies were made on why guinea pigs are resistant to carcinogenesis by 2-acetylaminofluorene. Cytochrome P-448 and arylhydrocarbon hydroxylase were not induced in either the microsomes and nuclei of guinea pigs by 3-methylcholanthrene treatment. 3-Methylcholanthrene treatment caused only 2-fold increase in the binding of 2-acetylaminofluorene to DNA in nuclei isolated from guinea pigs, while it caused 17-fold increase in the binding in rat nuclei. Microsomes from 3-methylcholanthrene treated rats had 5 times more effect than Microsomes from 3-methylcholanthrene treated guinea pigs on the binding of 2-acetylaminofluorene to DNA of nuclei from untreated guinea pigs. N-Hydroxy-2-acetylaminofluorene combined equally well with the DNA of rats and guinea pigs. In guinea pigs, there was a good correlation between the low inducibility of cytochrome P-448 and the low binding of 2-acetylaminofluorene to DNA. Our results clearly showed that guinea pigs are resistant to tumor induction by 2-acetylaminofluorene through inability to carry out the first step of activation of 2-acetylaminofluorene.     

增加环境丰富化模具对实验豚鼠生长及行为的影响

目的在实验豚鼠饲养盒内增加梯形和管形两种不同的模具,进行环境丰富化模具对豚鼠生长及行为影响的研究。方法每组豚鼠饲养4周,每周称1次体重,记录体重变化趋势,并观察豚鼠行为变化。结果放入模具的豚鼠生长情况优越于对照组,管形模具优于其他实验组。结论增加环境丰富化模具有利于豚鼠生长,且管形模具更接近豚鼠自然洞穴状态,更加有利于豚鼠实现自然躲藏行为和良好的生长、生活。     

花色豚鼠与白化豚鼠静脉血电解质、酸碱平衡及血气的比较学研究

目的比较研究花色豚鼠与白化豚鼠静脉血电解质、酸碱平衡及血气情况。方法分别取健康成年花色豚鼠和白化豚鼠,利用便携式多功能麻醉机经异氟烷吸入麻醉后,腹主静脉取血,经NOVA血气．电解质分析仪全自动分析测定电解质、酸碱平衡及血气等指标。结果花色豚鼠的Cl-、pH、SBC、PO2、SV O2、O2ct均显著低于白化豚鼠（P〈0．05,P〈0．01）,而PCO2显著高于白化豚鼠（P〈O．05）。结论花色豚鼠的携氧能力明显低于白化豚鼠,可以作为血瘀证和亚健康模型研究较好的实验动物。     

Comparison of in vitro platelet aggregation and its inhibition by three antithrombotic drugs between human and guinea pig

Platelets of guinea pigs are frequently used to evaluate the effect of new antiplatelet agents. Although several studies have compared the platelet aggregation between humans and guinea pigs, but so far the information is still limited. In this study, we compare the inhibitory effect of aspirin, dipyridamole and pentoxifylline on the platelet aggregation induced by adenosine diphosphate (ADP), collagen, arachidonic acid and thrombin between humans and guinea pigs. The results for humans and guinea pigs were compared and analysed by two-way analysis of variance (ANOVA). Our results showed: 1. The trends wherein these three drugs suppressed collagen-induced platelet aggregation was very similar in humans and guinea pigs. 2. In ADP-induced aggregation, the trend of inhibition caused by the three drugs was also similar in humans and guinea pigs except that a difference in platelet disaggregation at a late phase of platelet aggregation was noted. 3. In arachidonic acid- and thrombin-induced aggregations, the trend of inhibition caused by the three drugs was somewhat different in humans and guinea pigs. 4. Considering all activators as a whole, it was found that the status of platelet disaggregation at the late phase of platelet aggregation was different in humans and guinea pigs. Therefore, we concluded that: 1. Collagen was the most appropriate platelet activator when we used platelets of guinea pigs to study the effect of new antiplatelet agents. 2. When platelets of guinea pigs were used to study platelet aggregation, no matter which activator was used, we should avoid using the late phase of aggregation as the control index for comparison, because the results thus obtained might not be applicable to human platelets.     

无菌豚鼠与普通豚鼠血液学参数的比较

目的对普通级豚鼠进行剖宫产,培育无菌豚鼠模型,并比较无菌豚鼠和普通级豚鼠的血液学参数。方法行子宫摘除术摘除子宫,在无菌隔离器中将子宫剥离取仔,用人工哺乳的方法将仔豚鼠培育成无菌豚鼠,并在固定的周期检测豚鼠的无菌情况。采用全血细胞计数分析仪、全自动血液生化分析仪测定无菌豚鼠、普通豚鼠的血常规和血生化参数。用SPSS12.0进行统计分析。结果无菌豚鼠和普通豚鼠在白细胞(WBC)、嗜碱性粒细胞数(BA#)、单核细胞百分比(MO)、血红蛋白浓度(MCHC)、中性粒细胞数(NE#)、嗜酸性粒细胞数(EO#)、淋巴细胞数(LY#)七个血常规指标上有差异显著性,其他指标没有显著性差异;谷丙转氨酶(ALT)、乳酸脱氢酶(LDH)、总蛋白(TP)、白蛋白(ALB)、葡萄糖(GLU)、总胆固醇(CHO)、总胆红素(TBIL)、高密度脂蛋白胆固醇(HDL-C)、低密度脂蛋白胆固醇(LDL-C)、甘油三酯(TG)、球蛋白(GLO)、A/G、K、Na、谷酰转肽酶(GGT)15个指标上差异有显著性,其他指标差异无显著性。结论通过规范的子宫摘除术和人工喂养的方法获得符合标准的无菌豚鼠,与普通豚鼠在多项血液学指标上差异有显著性。     

Hypothermia tolerance in guinea pigs with experimental myasthenia gravis

Hypothermia tolerance was studied in guinea pigs with experimental myasthenia gravis induced by immunization with homologous thymus extract and Freund's complete adjuvant. Untreated guinea pigs and guinea pigs immunized with liver extract and Freund's complete adjuvant served as controls. Thymus-immunized guinea pigs survived to a significantly lower temperature at asystole than did the liver-immunized controls. This finding is consistent with a slight diminution in temperature maintenance mechanisms in guinea pigs with experimental autoimmune thymitis. The observed increase in hypothermia tolerance may be due to impaired shivering as a consequence of the partial neuromuscular block demonstrable in the myasthenia gravislike state.     

Hepatic 3-hydroxy-3-methylglutaryl coenzyme A reductase activity and cholesterol 7 alpha-hydroxylase activity in neonatal guinea pig.

Optimal assay conditions for hepatic HMG-CoA reducatase activity and cholesterol 7 alpha-hydroxylase activity in the guinea pig were determined. These two enzyme activities were studied in the liver of newborn guinea pigs during the first three postnatal weeks. Hepatic HMG-CoA reductase activity of neonatal guinea pigs was similar to that of adult animals. However, cholesterol 7 alpha-hydroxylase activity of newborns was about one-third of that in adult guinea pigs. This finding suggests that the system for bile acid synthesis in the neonatal guinea pigs is underdeveloped.     

Histopathology of <Emphasis Type="Italic">Rhipicephalus sanguineus</Emphasis> (Acari: Ixodidae) ticks fed on resistant hosts

Histological features of Rhipicephalus sanguineus ticks fed on dog, a non resistant host, and on guinea pig, a resistant host, were compared. Unfed ticks and ticks from each host species were collected during first and third infestation and processed for histology. Many ticks from guinea pigs, especially during third infestation, were unattached, dehydrated and small. Only the midgut of ticks fed on guinea pigs had host leukocytes. Vacuolization of midgut cells was observed in all ticks, with exception of those fed on dogs for more than 96 h. Ticks of guinea pigs, particularly from third infestation, had vacuolated tracheae and swelling of malpighian tubules. Solely ticks from third infestation of guinea pigs displayed vacuolization of oocytes. Ticks fed on guinea pigs also had an increased number of guanine spherules. Observed alterations in ticks from guinea pigs are discussed.     

缺氧条件下FMMU白化豚鼠和杂色豚鼠心肌线粒体形态变化比较研究

目的　比较研究在缺氧条件下FMMU白化豚鼠和杂色豚鼠心肌线粒体的形态变化。方法　将FMMU白化豚鼠和杂色豚鼠置于常压缺氧舱内分别缺氧 7d、14d、2 1d ,复制常压缺氧模型 ,分别取FMMU白化豚鼠和杂色豚鼠心肌 ,电镜下观察心肌线粒体形态的变化。结果　在同一缺氧时间 ,二者的超微结构变化程度不同 ;在不同缺氧时间 ,同种豚鼠的变化程度也不同。结论　在缺氧条件下 ,FMMU白化豚鼠心肌线粒体的变化程度较杂色豚鼠轻 ,提示可能白化豚鼠对缺氧的耐受性优于杂色豚鼠     

The daily pattern of heart rate, body temperature, and locomotor activity in guinea pigs.

We studied the characteristics of the rhythmicity of heart rate (HR), body temperature (BT), and locomotor activity (LA) in conscious and unrestrained guinea pigs using a telemetry system. HR and/or LA in some guinea pigs clearly showed circadian rhythms, but in others there were no significant daily patterns; BT did not show significant daily rhythms. These results suggest that guinea pigs might have different individual characteristics of rhythmicity, and we should, therefore, be careful when using guinea pigs in chrono-biomedical research. We believe that the results of this study may be useful for future biomedical studies using guinea pigs.     

A new guinea pig mutant with abnormal hair production and immunodeficiency

Hairless guinea pigs were born in a closed colony of Hartley guinea pigs. At birth, hairless guinea pigs were smaller than littermates, had wrinkled skin and stunted vibrissae. The most striking abnormality histologically was distension of the upper portion of the pilary canal with thickening of the epidermis. Hairlessness resulted from production of abnormal hair shafts. Preliminary work indicated that in addition to hairlessness, the guinea pigs were athymic or hypothymic. Initial immunologic studies showed that the guinea pigs also were agammaglobulinemic. Animals that survived the weaning period died of infections that are usually associated with immunodeficiencies, such as systemic cytomegalovirus, systemic balantidiasis and Pneumocystis carinii pneumonia.     

Participation of capsaicin-sensitive neurons in the cardiovascular effects of neurotensin in guinea pigs

Intravenous (IV) infusions of neurotensin (NT) in anesthetized guinea pigs elicited dose-dependent pressor effects and tachycardia. Both effects were significantly reduced or abolished in guinea pigs given a chronic treatment with the neurotoxin capsaicin. In guinea pig isolated atria NT evoked a positive inotropic and chronotropic effect. Both effects were completely abolished in atria derived from capsaicin-treated guinea pigs. The positive inotropic and chronotropic effects of NT in guinea pig atria were mimicked by capsaicin and calcitonin gene-related peptide (CGRP). These results were interpreted as an indication that NT produces its cardiovascular effects in guinea pigs by activating capsaicin-sensitive sensory neurons.     

Comparison of the host ranges and antigenicity of Cryptosporidium parvum and Cryptosporidium wrairi from guinea pigs.

Oocysts of a Cryptosporidium isolate from guinea pigs were not infectious for adult mice, but were infectious for two of three newborn calves and for suckling mice. However, oocysts isolated from calves or mice infected with guinea pig Cryptosporidium were not infectious for guinea pigs. Four isolates of C. parvum from calves were incapable of infecting weanling guinea pigs. Microscopic examination of tissue from the colon and cecum of suckling guinea pigs inoculated with C. parvum revealed sparse infection of some pups. These host range studies and previously described differences in 125I-labeled oocyst surface protein profiles between Cryptosporidium sp. from guinea pigs and C. parvum suggest they are distinct species. We propose the name Cryptosporidium wrairi be retained. Studies with monoclonal antibodies indicate that C. wrairi and C. parvum are antigenically related.     

Observations on the Parathyroid Glands of Guinea Pigs Affected with Metastatic Calcification

Soft tissue calcification in guinea pigs has been attributed to a mineral imbalance, especially a relative or absolute magnesium deficiency. An associated chronic tubular nephritis has been reported and was substantiated in the present study. The location of the parathyroid glands of guinea pigs was established, and their size estimated by microscopic methods. The size and morphologic characteristics of parathyroids of guinea pigs affected with metastatic calcification were indistinguishable from parathyroids of healthy guinea pigs.     

重组人磷脂酶D2在体内能明显抑制慢性哮喘豚鼠血清中GPI-PLD的表达

 通过建立慢性豚鼠哮喘模型,研究重组人磷脂酶D2(rhPLD2)干预慢性哮喘豚鼠血清中糖基化磷脂酰肌醇特异性磷脂酶D(GPI-PLD)含量的变化,探寻可能的机制. 以rhPLD2干预慢性哮喘豚鼠,用TX-114分相法检测豚鼠血清中GPI-PLD酶活性.与正常状态豚鼠相比较,慢性哮喘状态豚鼠其血清中GPI-PLD酶活性显著升高.但以rhPLD2及地塞米松干预慢性哮喘豚鼠后,该指标显著下降. rhPLD2可通过抑制其血清中GPI-PLD酶活性表达,来抑制哮喘发生过程中的炎症反应.     

Effect in neonatal thymectomy on experimental autoimmune thyroiditis in guinea pigs.

These studies examined the effect of neonatal thymectomy on the induction of experimental autoimmune thyroiditis (EAT) in the guinea pigs. Thymectomy was found to result in a consistent and profound inhibition of the development of lesions of EAT in both strain 2 and strain 13 guinea pigs. Thymectomized guinea pigs also had reduced antibody titers to guinea pig thyroglobulin (GPTG), while delayed hypersensitivity reactions to GPTG were less markedly affected by thymectomy. Thymectomized guinea pigs had significant functional peripheral T cells as evidenced by normal responses of lymph node cells to T cell mitogens. These results indicate that a T cell subpopulation which is sensitive to neonatal thymectomy is required for the development of EAT and antithyroglobulin antibody in the guinea pig.     

Comparison of the Host Ranges and Antigenicity of Cryptosporidium parvum and Cryptosporidium wrairi from Guinea Pigs

ABSTRACT. Oocysts of a Cryptosporidium isolate from guinea pigs were not infectious for adult mice, but were infectious for two of three newborn calves and for suckling mice. However, oocysts isolated from calves or mice infected with guinea pig Cryptosporidium were not infectious for guinea pigs. Four isolates of C. parvum from calves were incapable of infecting weanling guinea pigs. Microscopic examination of tissue from the colon and cecum of suckling guinea pigs inoculated with C. parvum revealed sparse infection of some pups. These host range studies and previously described differences in ¹²⁵I-labeled oocyst surface protein profiles between Cryptosporidium sp. from guinea pigs and C. parvum suggest they are distinct species. We propose the name Cryptosporidium wrairi be retained. Studies with monoclonal antibodies indicate that C. wrairi and C. parvum are antigenically related.