Age- and sex-associated differences in hematology and biochemistry parameters of Dunkin Hartley guinea pigs (Cavia porcellus).

The Dunkin Hartley is the most common guinea pig strain used in biomedical research, particularly for studies of asthma, allergy, infectious disease, reproduction, and osteoarthritis. Minimally invasive blood tests, such as complete blood counts and serum biochemistry profiles, are often collected for diagnostics and laboratory analyses. However, reference intervals for these assays have not yet been well-documented in this strain. The purpose of this study was to establish reference intervals for hematologic and biochemical parameters of Dunkin Hartley guinea pigs and determine age- and sex-related differences. Hematologic and biochemical parameters were retrospectively obtained from 145 male and 68 female guinea pigs between 2 and 15 months of age. All blood parameters were analyzed by a veterinary clinical pathology laboratory. Reference intervals were established according to the American Society for Veterinary Clinical Pathology guidelines. Age- and sex-related differences were determined using unpaired t-tests or nonparametric Mann-Whitney tests. Hematocrit, red blood cell distribution width, mean platelet volume, white blood cell count, heterophils, monocytes, eosinophils, glucose, blood urea nitrogen, creatinine, calcium, magnesium, total protein, albumin, globulin, cholesterol, aspartate aminotransferase, gamma glutamyl transferase, and bicarbonate increased with age. Mean corpuscular hemoglobin concentration, cellular hemoglobin concentration mean, platelets, lymphocytes, phosphorus, albumin/globulin ratio, alkaline phosphatase, anion gap, and calculated osmolality decreased with age. Males had higher hemoglobin, hematocrit, red blood cell count, mean corpuscular hemoglobin concentration, white blood cell count, heterophils, Foa-Kurloff cells, alanine aminotransferase, and bicarbonate and lower mean corpuscular volume, red blood cell distribution width, platelets, mean platelet volume, eosinophils, total protein, albumin, globulin, cholesterol, potassium, anion gap, calculated osmolality, and iron compared to females. Establishing age and sex differences in hematologic and biochemical parameters of Dunkin Hartley guinea pigs provides valuable insight into their physiology to better evaluate diagnostics and experimental results.

Hematologic Parameters and Blood Cultures from the Gingival Vein Compared with the Cranial Vena Cava in Guinea Pigs.

Blood collection methods in guinea pigs are limited due to the animals' compact neck, short limbs, and lack of a tail. Gingival venipuncture is a recently described blood sampling technique that is minimally traumatic with no significant alterations in hematologic parameters when multiple blood samples were collected weekly for 6 wk. The purpose of this study was to determine whether the gingival vein can be used as an alternative blood collection site in guinea pigs, such that: (1) hematologic parameters would be consistent with samples collected from the cranial vena cava; and (2) no contaminants from the oral cavity would be introduced into the sample. Blood samples were obtained from both the gingival vein and cranial vena cava of anesthetized Dunkin Hartley guinea pigs for CBC (n = 9) and aerobic blood cultures (n = 10). Only MCV was significantly different between sampling sites. Bland-Altman analyses calculated a small mean bias for all hematologic parameters, indicating clinical interpretation is unlikely to be affected by the sampling site. Bacterial growth occurred in all 5 gingival vein blood samples prepared by using saline and 2 of the 5 prepared with dilute chlorhexidine. Bacteria did not grow from any cranial vena caval blood samples prepared with dilute chlorhexidine. No clinical signs of hemorrhage or trauma were detected at either site. These results provide evidence that gingival venipuncture can be used as an alternative blood collection method for guinea pigs for hematologic analysis but should not be used for blood culture.

Hematology and Clinical Chemistry Reference Intervals for Inbred Strain 13/n Guinea Pigs (Cavia Porcellus ).

Inbred Strain 13/N Guinea Pigs are Frequently Used As Animal Models in Studies of Emerging and High-pathogenicity Viruses. To Date, Clinical Reference Intervals Have Not Been Established for Hematology and Clinical Chemistry Parameters in This Strain. We Obtained Whole-blood Samples from the Cranial Vena Cava of Healthy Strain 13/N Colony Animals for Inhouse Cbc and Clinical Chemistry Analyses. Analyte Values Were Investigated to Determine Subpopulation Differences According to Age and Sex. Glucose, Albumin, Alp, Lymphocyte Percentage, Hgb, and Mchc Decreased with Age, Whereas Neutrophil and Monocyte Percentages, Bun, Creatinine, Calcium, and Amylase Increased with Age. Total Protein and Wbc Counts Increased Over the First 300 D of Life Before Stabilizing. Across All Age Categories, Female Guinea Pigs Consistently Had Lower Rbc, Hct, Hgb, Alt, Alp, and Amylase Levels and Higher Mcv Values Than Males. These Trends Were Strongest in Adults (age, 151 Through 900 D). Most Parameters Stabilized by 300 D; Previous Studies Used 60 D or 120 D As Adult Age and 90 to 120 D As Sexual Maturity. We Recommend Age Group Definitions of 0 Through 150 D for Juveniles, 151 Through 900 D for Adults, and Older Than 900 D for Geriatric Adult Strain 13/N Guinea Pigs.

Animal infection studies of two recently discovered African bat paramyxoviruses, Achimota 1 and Achimota 2.

Bats are implicated as the natural reservoirs for several highly pathogenic viruses that can infect other animal species, including man. Here, we investigate the potential for two recently discovered bat rubulaviruses, Achimota virus 1 (AchPV1) and Achimota virus 2 (AchPV2), isolated from urine collected under urban bat (Eidolon helvum) roosts in Ghana, West Africa, to infect small laboratory animals. AchPV1 and AchPV2 are classified in the family Paramyxoviridae and cluster with other bat derived zoonotic rubulaviruses (i.e. Sosuga, Menangle and Tioman viruses). To assess the susceptibility of AchPV1 and AchPV2 in animals, infection studies were conducted in ferrets, guinea pigs and mice. Seroconversion, immunohistological evidence of infection, and viral shedding were identified in ferrets and guinea pigs, but not in mice. Infection was associated with respiratory disease in ferrets. Viral genome was detected in a range of tissues from ferrets and guinea pigs, however virus isolation was only achieved from ferret tissues. The results from this study indicate Achimota viruses (AchPVs) are able to cross the species barrier. Consequently, vigilance for infection with and disease caused by these viruses in people and domesticated animals is warranted in sub-Saharan Africa and the Arabian Peninsula where the reservoir hosts are present.

Sub-chronic toxicopathological study of lantadenes of Lantana camara weed in Guinea pigs.

BACKGROUND: In the field conditions, animals regularly consume small quantities of lantana leaves either while grazing or due to mixing with regular fodder. The hypothesis of this study was that consumption of lantana toxins over a long period of time leads to progression of sub-clinical disease. Toxicopathological effects of sub-chronic (90 days) administration of lantadenes of L. camara were investigated in guinea pigs. For this, a total of 40 animals were divided into 5 groups whereby groups I, II, III and IV were orally administered lantadenes, daily at the dose of 24, 18, 12, and 6 mg/kg bw, respectively while group V was control. The animals were evaluated by weekly body weight changes, haematology, serum liver and kidney markers, tissue oxidative markers and histopathology. RESULTS: The results of significant decrease in weekly body weights, haematology, liver and kidney marker enzymes (alanine aminotransaminase, aspartate aminotransaminase, acid phosphatase and creatinine), oxidation stress markers (lipid peroxidation, reduced glutathione, superoxide dismutase and catalase) in liver and kidneys, histopathology, and confirmation of fibrous collagenous tissue proliferation by Masson's Trichome stain showed that lantadenes led to a dose-dependent toxicity in decreasing order with the highest dose (24 mg/kg bw) producing maximum lesions and the lowest dose (6 mg/kg bw) producing minimum alterations. CONCLUSIONS: The study revealed that lantadenes which are considered to be classical hepatotoxicants in acute toxicity produced pronounced nephrotoxicity during sub-chronic exposure. Further studies are needed to quantify the levels of lantadenes in blood or serum of animals exposed to lantana in field conditions which would help to assess the extent of damage to the vital organs.

SB223412, a neurokinin-3 receptor-selective antagonist, suppresses testosterone secretion in male guinea pigs.

Guinea pigs are important zoo animals and have been recommended for animal-assisted activities or therapy, however there are problems concerning testosterone inducing aggressive or sexual behaviors in male guinea pigs. Testicular testosterone secretion is regulated by pulsatile gonadotropin releasing hormone (GnRH)/luteinizing hormone (LH) release in mammals. The mechanism generating GnRH/LH pulses is thought to be governed by kisspeptin neurons, which coexpress neurokinin B (NKB) and dynorphin A (Dyn), in the arcuate nucleus (ARC). Kisspeptin neurons in the ARC are frequently referred to as KNDy neurons. The purpose of this study was to examine whether the antagonization of NKB-neurokinin-3 receptor (NK3R) signaling can manipulate testosterone secretion in male guinea pigs. A single subcutaneous administration or 7 days of oral administration of an NK3R-selective antagonist, SB223412 (50 mg/body), significantly decreased plasma testosterone levels in male guinea pigs. In vitro binding assays confirmed that SB223412 has a high affinity to guinea pig NK3R. These results suggest that SB223412 could be used as an orally-available compound to suppress testosterone levels in male guinea pigs. Double labeling in situ hybridization of kisspeptin and either NKB or Dyn showed that kisspeptin-expressing neurons contained NKB (77.9%) or Dyn (62.3%) in the ARC, suggesting the presence of KNDy neurons in the ARC of guinea pigs. In conclusion, the present study shows that SB223412 could be a candidate compound to suppress testosterone secretion in male guinea pigs for controlling sexual and aggressive behaviors in the species.

Blood profiles in unanesthetized and anesthetized guinea pigs (Cavia porcellus).

The guinea pig is a common animal model that is used in biomedical research to study a variety of systems, including hormonal and immunological responses, pulmonary physiology, corticosteroid response and others. However, because guinea pigs are evolutionarily a prey species, they do not readily show behavioral signs of disease, which can make it difficult to detect illness in a laboratory setting. Minimally invasive blood tests, such as complete blood counts and plasma biochemistry assays, are useful in both human and veterinary medicine as an initial diagnostic technique to rule in or rule out systemic illness. In guinea pigs, phlebotomy for such tests often requires that the animals be anesthetized first. The authors evaluated hematological and plasma biochemical effects of two anesthetic agents that are commonly used with guinea pigs in a research setting: isoflurane and a combination of ketamine and xylazine. Hematological and plasma biochemical parameters were significantly different when guinea pigs were under either anesthetic, compared to when they were unanesthetized. Plasma proteins, liver enzymes, white blood cells and red blood cells appeared to be significantly altered by both anesthetics, and hematological and plasma biochemical differences were greater when guinea pigs were anesthetized with the combination of ketamine and xylazine than when they were anesthetized with isoflurane. Overall these results indicate that both anesthetics can significantly influence hematological and plasma biochemical parameters in guinea pigs.

Hematological assessment in pet guinea pigs (Cavia porcellus): blood sample collection and blood cell identification.

Pet guinea pigs are presented to veterinary clinics for routine care and treatment of clinical diseases. In addition to obtaining clinical history and exam findings, diagnostic testing may be required, including hematological assessments. This article describes common blood collection methods, including venipuncture sites, the volume of blood that can be safely collected, and handling of the blood. Hematological parameters for normal guinea pigs are provided for comparison with in-house or commercial test results. A description of the morphology of guinea pig leukocytes is provided to assist in performing a differential count.

Animal housing and welfare: effects of housing conditions on body weight and cortisol in a medium-sized rodent (Cavia aperea).

Rodents are the most abundant experimental nonhuman animals and are commonly studied under standard laboratory housing conditions. As housing conditions affect animals' physiology and behavior, this study investigated the effects of indoor and outdoor housing conditions on body weight and cortisol level of wild cavies, Cavia aperea. The changing housing condition strongly influenced both parameters, which are commonly used as indicators for animal welfare. The transfer from outdoor to indoor enclosures resulted in a body-weight loss of about 8%. In contrast, animals kept indoors showed a substantial weight gain of about 12% when they were transferred outdoors. These effects were reversible. To substantiate a connection between body-weight changes and the health states of the animals, blood basal cortisol concentrations were measured. Animals kept outdoors had significantly lower cortisol levels than did animals kept indoors. These results imply that indoor conditions have a direct effect on the animals' states. The physiological and metabolic consequences as well as potential welfare aspects should be taken into account when planning experimental work, especially on nondomestic animals.

Species differences in developmental toxicity of epoxiconazole and its relevance to humans.

Epoxiconazole, a triazole-based fungicide, was tested in toxicokinetic, prenatal and pre-postnatal toxicity studies in guinea pigs, following oral (gavage) administration at several dose levels (high dose: 90 mg/kg body weight per day). Maternal toxicity was evidenced by slightly increased abortion rates and by histopathological changes in adrenal glands, suggesting maternal stress. No compound-related increase in the incidence of malformations or variations was observed in the prenatal study. In the pre-postnatal study, epoxiconazole did not adversely affect gestation length, parturition, or postnatal growth and development. Administration of epoxiconazole did not alter circulating estradiol levels. Histopathological examination of the placentas did not reveal compound-related effects. The results in guinea pigs are strikingly different to those observed in pregnant rats, in which maternal estrogen depletion, pathological alteration of placentas, increased gestation length, late fetal death, and dystocia were observed after administration of epoxiconazole. In the studies reported here, analysis of maternal plasma concentrations and metabolism after administration of radiolabeled epoxiconazole demonstrated that the different results in rats and guinea pigs were not due to different exposures of the animals. A comprehensive comparison of hormonal regulation of pregnancy and birth in murid rodents and primates indicates that the effects on pregnancy and parturition observed in rats are not applicable to humans. In contrast, the pregnant guinea pig shares many similarities to pregnant humans regarding hormonal regulation and is therefore considered to be a suitable species for extrapolation of related effects to humans.

Hypervitaminosis D in guinea pigs with α-mannosidosis.

A colony of guinea pigs (n = 9) with α-mannosidosis was fed a pelleted commercial laboratory guinea pig diet. Over 2 mo, all 9 guinea pigs unexpectedly showed anorexia and weight loss (11.7% to 30.0% of baseline weight), and 3 animals demonstrated transient polyuria and polydipsia. Blood chemistry panels in these 3 guinea pigs revealed high-normal total calcium, high-normal phosphate, and high ALP. Urine specific gravity was dilute (1.003, 1.009, 1.013) in the 3 animals tested. Postmortem examination of 7 animals that were euthanized after failing to respond to supportive care revealed renal interstitial fibrosis with tubular mineralization, soft tissue mineralization in multiple organs, hepatic lipidosis, and pneumonia. Analysis of the pelleted diet revealed that it had been formulated with a vitamin D3 content of more than 150 times the normal concentration. Ionized calcium and 25-hydroxyvitamin D values were both high in serum saved from 2 euthanized animals, confirming the diagnosis of hypervitaminosis D. This report discusses the clinical signs, blood chemistry results, and gross and histologic findings of hypervitaminosis D in a colony of guinea pigs. When unexpected signs occur colony-wide, dietary differentials should be investigated at an early time point.

[Reference ranges for biochemical parameters in guinea pigs for the Vettest®8008 blood analyzer]. / Referenzwerte blutchemischer Parameter bei Meerschweinchen bestimmt mit dem Vettest® 8008.

OBJECTIVE: Studies to establish reference ranges for blood chemistry in guinea pigs are scarce and always apply to bench chemistry. Most veterinary surgeries, however, use dry chemistry methods for in-house blood analysis, for which no reference ranges are available in guinea pigs. In this study, reference ranges for guinea pigs were established by the use of a common dry chemistry blood analyzer (Vettest®8008). MATERIAL AND METHODS: The animals were pets from clients of the Potsdam Veterinary Hospital (24 males, 34 females). The age ranged from 8 weeks to 5 years. Plasma samples were prepared for routine blood chemistry analysis. The investigation comprised 20 parameters (see below). Reference ranges were established via SPSS Statistics 17.0 from 2.5%- and 97.5%-percentiles. RESULTS: Enzymes: alkaline phosphatase: 50.80-328.10 U/l; alanine aminotransferase: 41.45-165.35 U/l; amylase: 726.93-1831.55 U/l; aspartate aminotransferase: 25.25 to 349.23 U/l; creatine kinase: 66.13-1255.40 U/l; γ-glutamyl transferase: 0.45-90.75 U/l; lactate dehydrogenase: 5.61-1503.00 U/l, lipase: no measurable activity. Substrates: albumin: 17.45-31.65 g/l; ammonia: 4.80-225.30 mmol/l; cholesterol: 0.00-2.06 mmol/l; creatinine: 23.90 to 73.45 µmol/l; total bilirubin: 2.00-17.60 µmol/l; total protein: 50.00-70.85 g/l; glucose: 4.62-19.55 mmol/l; blood urea nitrogen: 2.04-11.28 mmol/l; triglycerides: 0.46-4.23 mmol/l. Globulins results by calculation: 30.43-42.00 g/l. Electrolytes: anorganic phosphate: 0.72-2.12 mmol/l, calcium: 2.58-3.16 mmol/l; magnesium: 0.72 to 1.60 mmol/l. CONCLUSIONS: Some major differences were found between the results of three recent studies and the present study, respectively. This leads to the conclusion that reference ranges obtained by differing methods are not necessarily useful for the veterinary in-house laboratory. Instead, in-house analyzers require their own specific reference ranges. Possible reasons for the differences in reference ranges of the compared studies may be due to undetected subclinical diseases and the use of differing chemical or statistical methods.

Ocorrência de siphonaptera em preá cavia aperea exerleben, 1777 (rodentia: caviidae) no Rio Grande do Sul, Brasil / Occurrence of siphonaptera in cavia aperea exerleben, 1777 (rodentia: caviidae) in the state of Rio Grande do Sul, southern Brazil

Due to limited knowledge of Siphonaptera fauna of the Cavia aperea (Brazilian guinea pig) in the State of Rio Grande do Sul, 43 specimens were examined. Six percent of the Brazilian guinea pigs were parasitized with Siphonaptera, which were identified as Polygenis (Neopolygenis) atopus and Polygenis (Polygenis) axius proximus (Rhopalopsyllidae), both with 2.3% of prevalence. P. (Neopolygenis) atopus and P. (Polygenis) axius proximus are reported for the first time on C. aperea in the State of Rio Grande do Sul, Southern Brazil.

Serum thyroxine concentrations in clinically healthy pet guinea pigs (Cavia porcellus).

BACKGROUND: Guinea pigs (Cavia porcellus) are often presented as patients in veterinary practice. Nevertheless, only limited information is available about endocrine diseases or thyroxine reference values for the species. OBJECTIVE: The aim of this study was to determine serum thyroxine concentrations in a well-defined population of clinically healthy pet guinea pigs. METHODS: Between October 2007 and July 2008, serum samples were collected from 40 clinically healthy guinea pigs of different sexes, ages, and breeds that were presented to our clinic for a general health check or for castration. Pregnant females were excluded from the study. Thyroxine concentration was measured using a chemiluminescence test (Immulite 2000 Canine Total T4). RESULTS: Thyroxine concentrations ranged from 14.2 to 66.9 nmol/L (1.1-5.2 microg/dL) with a median value of 27.0 nmol/L (2.1 microg/dL). Females (n=16) had significantly (P=.039; Mann-Whitney U-test) lower thyroxine values than castrated males (n=8), whereas no differences were found between females and intact males (n=16) or between intact and castrated males. No significant correlation was found between thyroxine concentration and age. CONCLUSION: This is the first report of serum thyroxine reference values for a well-defined population of healthy pet guinea pigs as measured by a chemiluminescence assay. The results were higher than those previously reported for this species and emphasize the importance of using appropriate reference intervals for the diagnosis of hyperthyroidism.

Estereología comparativa entre el bazo del cuye (Cavia porcellus) y la rata (Rattus novergicus, Sprague Dawley) / Comparative stereology between the spleen of the Guinea pig (Cavia porcellus) and the rat (Rattus novergicus, Sprague Dawley)

El bazo es el órgano linfático periférico más grande del organismo y conocer sus aspectos morfológicos cuantitativos es importante para determinar posibles patologías. El objetivo del estudio fue determinar en dos especies: cuye (Cavia porcellus) y rata (Rattus novergicus Sprague Dawley), las características estereológicas del bazo, para obtener patrones de normalidad cuantitativos, los que servirán de base para futuros estudios morfofuncionales. Se utilizaron 5 bazos de cada especie, clínicamente sanos, obtenidos del Bioterio de la Universidad de La Frontera, Temuco, Chile. Los bazos fueron disecados y fijados en formalina tamponada al 10 por ciento y se determinó el volumen de éstos por el método de Scherle. Se obtuvieron 5 trozos por medio de Orientador los que fueron incluidos en paraplast. De cada trozo se obtuvieron 5 cortes histológicos de 3 micrones m de grosor y separados 200 micrones m entre sí, los cuales fueron teñidos con H-E. El porcentaje de pulpa roja, pulpa blanca y zona marginal en el bazo del cuye fue: 65,14 por ciento, 21,96 por ciento y 12,67 por ciento, respectivamente, y en la rata 53,9 por ciento de pulpa roja, 25,75 por ciento pulpa blanca y 15,87 por ciento de zona marginal. El número total de folículos fue 8,33 x 10² y 5,73x 10² para el cuye y la rata, respectivamente. Los resultados concuerdan con los obtenidos por otros autores, pudiéndose señalar un patrón cuantitativo del porcentaje de los compartimentos esplénicos de normalidad, que se podría considerar para futuros estudios morfo-funcionales.

The spleen is the largest peripheral lymphoid organ of the body so it is essential to know their morphological quantitative aspects in order to identify potential abnormalities. The aim of this study was to determine the parameters stereological spleen in normal two species commonly used in research such as the guinea pig and rat, to obtain quantitative patterns of normality, which will serve as a basis for future studies morphofunctional. 5 spleens were used for each species (Cavia porcellus and Rattus novergicus, Sprague Dawley) obtained from biotery the Universidad de La Frontera, Temuco, Chile. The spleens were dissected and fixed in formalin buffered to 10 percent and the volume is determined by the of Scherle method. 5 pieces were obtained through Orientator and these were included in paraplast. Each piece was performed histological cuts of 3 mm thick and separated 200 µm each other, which were stained with H-E. The percentage of redpulp, whitepulp and marginal zone in the Guinea pig was: 65.14 percent, 21.96 percent and 12.67 percent respectively, and in the rat 53.9 percent pulpred, 25.75 percent whitepulp and 15.87 percent of marginal zone. The total number of follicles was 8.33 x 10²follicles and 5.73 x 10² follicles for the Guinea pig and rat, respectively. The results are consistent with those obtained by other authors might identify a pattern of quantitative percentage of splenic compartments of normality that could be considered for future studies morpho-functional.

The Guinea pig as a preclinical model for demonstrating the efficacy and safety of statins.

Statins, because of their excellent efficacy and manageable safety profile, represent a key component in the current armamentarium for the treatment of hypercholesterolemia. Nonetheless, myopathy remains a safety concern for this important drug class. Cerivastatin was withdrawn from the market for myotoxicity safety concerns. BMS-423526 [{(3R,5S)-7-[4-(4-fluorophenyl)-6,7-dihydro-2-(1-methylethyl)-5H-benzo[6,7]cyclohepta[1,2-b]pyridin-3-yl]-3,5-dihydroxy-heptenoic acid} sodium salt], similar to cerivastatin in potency and lipophilicity, was terminated in early clinical development due to an unacceptable myotoxicity profile. In this report, we describe the guinea pig as a model of statin-induced cholesterol lowering and myotoxicity and show that this model can distinguish statins with unacceptable myotoxicity profiles from statins with acceptable safety profiles. In our guinea pig model, both cerivastatin and BMS-423526 induced myotoxicity at doses near the ED(50) for total cholesterol (TC) lowering in plasma. In contrast, wide differences between myotoxic and TC-lowering doses were established for the currently marketed, more hydrophilic statins, pravastatin, rosuvastatin, and atorvastatin. This in vivo model compared favorably to an in vitro model, which used statin inhibition of cholesterol synthesis in rat hepatocytes and L6 myoblasts as surrogates of potential efficacy and toxicity, respectively. Our conclusion is that the guinea pig is a useful preclinical in vivo model for demonstrating whether a statin is likely to have an acceptable therapeutic safety margin.

Erythrocyte binding preference of avian influenza H5N1 viruses.

Five erythrocyte species (horse, goose, chicken, guinea pig, and human) were used to agglutinate avian influenza H5N1 viruses by hemagglutination assay and to detect specific antibody by hemagglutination inhibition test. We found that goose erythrocytes confer a greater advantage over other erythrocyte species in both assays.

Analysis of mosquito bloodmeals using RFLP markers.

An important variable in the amplification of arthropod vector-borne diseases is the degree of contact between human hosts and mosquito vectors. To analyze this interaction, a DNA based method was developed to differentiate human bloodmeals from other sources in the mosquito Anopheles stephensi (Diptera: Culicidae) Liston. A portion of the host mitochondrial DNA cytochrome B genes were PCR amplified and classified to the species level based on their restriction fragment length polymorphism (RFLP). The cytochrome B sequences showed sufficient interspecific polymorphism to distinguish between human, cow, sheep, chicken, and guinea pig hosts. XhoI could distinguish human from other vertebrates whereas TaqI alone could separate the others. The importance of these results in epidemiological studies of malaria and other vector borne diseases is discussed.

Novel two-parameter flow cytometry (MIL4/SSC followed by MIL4/CT7) allows for identification of five fractions of guinea pig leukocytes in peripheral blood and lymphoid organs.

Though the guinea pig has been an extremely useful animal model for a variety of diseases, the tools necessary to undertake a full-scale immunological analysis of the guinea pig have been lacking. For instance, traditional two-parameter forward/side scatter (FSC/SSC) flow cytometry, though effective in human and other animal models, is unable to adequately identify the distinct fractions of guinea pig peripheral blood leukocytes (PBL). We introduce here a new flow cytometric technique (MIL4/SSC followed by MIL4/CT7) which redresses this lack by identifying and characterizing five distinct fractions of PBL: neutrophils, lymphocytes, monocytes, eosinophils plus basophils, and the novel MIL4(-)SSC(large)CT7(high) population. The MIL4(-)SSC(large)CT7(high) cells possess cytoplasmic inclusion bodies of variable size that were positive for periodic acid Schiff (PAS). Their cell surface stained positive for the helper/inducer lymphocyte markers, T cell markers, CD45, Thy-1, asialo GM1 and FcR, but negative for B cell markers, such as membrane-type IgM, CD8 and MHC class II. The novel flow cytometric technique also allowed us to establish that the five leukocyte fractions were found in PBL, splenocytes, thymocytes and lymph node cells. Cells which were positive for inclusion bodies comprised 16.6% of splenocytes, 9.9% of PBL and 4.3% of liver cells, but were comparatively rare in lymph node cells, thymocytes, and BM cells. The novel flow cytometric technique introduced here will allow a better understanding of the response of each type of guinea pig leukocyte and thereby shed light on the diseases with which they are associated.

Purification and characterization of l,(l/d)-aminopeptidase from Guinea pig serum.

Mammalian sera contain enzymes that catalyze the hydrolytic degradation of peptidoglycans and molecules of related structure and are relevant for the metabolism of peptidoglycans. We now report on a novel L,(L/D)-aminopeptidase found in human and mammalian sera. The enzyme hydrolyses the pentapeptide L-Ala-D-iso-Gln-meso-DAP(omegaNH(2))-D-Ala-D-Ala yielding the free L-alanine and the respective tetrapeptide (K(M) 18 mM). L,(L/D)-aminopeptidase from guinea pig serum was highly purified in four chromatographic steps, up to 700-fold. Molecular weight of the enzyme was estimated by HPLC to be approximately 175,000. The configuration of alanine obtained by hydrolysis of the pentapeptide was determined by oxidation with L-amino acid oxidase. The amino acids sequence in the respective tetrapeptide was deduced from the results of mass spectrometry. The novel L,(L/D)-aminopeptidase also hydrolyzed alanine-4-nitroanilide (K(M)=0.6 mM) and several peptides comprising L-amino acids. Peptides containing D-amino acid at the amino end and L-Asp-L-Asp were not the substrates for this enzyme. The purified enzyme also exhibited enkephalin degrading activity, hydrolyzing enkephalins comprising L,L- and L,D-peptide bonds. The enzyme was inhibited strongly by metal chelating agents, bestatin and amastatin.