Hartley Strain Guinea Pigs Research Articles

Effect of gelatin methacryloyl hydrogel on healing of the guinea pig vaginal wall with or without mesh augmentation.

The aims of this study were to evaluate the effectiveness of gelatin methacryloyl as an adjunct to anterior vaginal wall injury with or without vaginal mesh compared with traditional repair with suture. Virginal cycling Hartley strain guinea pigs (n= 60) were randomized to undergo surgical injury and repair using either polyglactin 910 suture or gelatin methacryloyl for epithelium re-approximation or anterior colporrhaphy with mesh augmentation using either polyglactin 910 suture or gelatin methacryloyl for mesh fixation and epithelium re-approximation. Noninjured controls (n= 5) were also evaluated. After 4 days, 4 weeks, or 3 months, tissues were analyzed by hematoxylin & eosin in addition to immunolabeling for macrophages, leukocytes, smooth muscle, and fibroblasts. Surgical injury repaired with suture was associated with increased inflammation and vessel density compared with gelatin methacryloyl. Vimentin and α-smooth muscle actin expression were increased with gelatin methacryloyl at 4 days (p= 0.0026, p= 0.0272). There were no differences in changes in smooth muscle or overall histomorphology after 3months between the two closure techniques. Mesh repair with suture was also associated with increased inflammation and vessel density relative to gelatin methacryloyl. Quantification of collagen content by picrosirius red staining revealed increased thick collagen fibers throughout the implanted mesh with gelatin methacryloyl compared with suture at 4 weeks (0.62 ± 0.01 μm2 vs 0.55 ± 0.01, p = 0.018). Even at the long-term time point of 3 months, mesh repair with suture resulted in a profibrotic encapsulation of the mesh fibers, which was minimal with gelatin methacryloyl. Smooth muscle density was suppressed after mesh implantation returning to baseline levels at 3 months regardless of fixation with suture or gelatin methacryloyl. These results suggest that gelatin methacryloyl might be a safe alternative to suture for epithelium re-approximation and anchoring of prolapse meshes to the vagina and may improve chronic inflammation in the vaginal wall associated with mesh complications.

Replication-defective lymphocytic choriomeningitis virus vectors expressing guinea pig cytomegalovirus gB and pp65 homologs are protective against congenital guinea pig cytomegalovirus infection

BackgroundCongenital cytomegalovirus infection can be life-threatening and often results in significant developmental deficits and/or hearing loss. Thus, there is a critical need for an effective anti-CMV vaccine. ObjectiveTo determine the efficacy of replication-defective lymphocytic choriomeningitis virus (rLCMV) vectors expressing the guinea pig CMV (GPCMV) antigens, gB and pp65, in the guinea pig model of congenital CMV infection. MethodsFemale Hartley strain guinea pigs were divided into three groups: Buffer control group (n=9), rLCMV-gB group (n=11), and rLCMV-pp65 (n=11). The vaccines were administered three times IM at 1.54×106FFU per dose at 21-day intervals. At two weeks after vaccination, the female guinea pigs underwent breeding. Pregnant guinea pigs were challenged SQ at ∼45–55 days of gestation with 1×105PFU of GPCMV. Viremia in the dams, pup survival, weights of pups at delivery, and viral load in both dam and pup tissues were determined. ResultsPup survival was significantly increased in the LCMV-gB vaccine group. There was 23% pup mortality in the gB vaccine group (p=0.044) and 26% pup mortality in the pp65 vaccine group (p=0.054) compared to 49% control pup mortality. The gB vaccine induced high levels of gB binding and detectable neutralizing antibodies, reduced dam viremia, and significantly reduced viral load in dam tissues compared to control dams (p<0.03). Reduced viral load and transmission in pups born to gB-vaccinated dams was observed compared to pups from pp65-vaccinated or control dams. ConclusionsThe rLCMV-gB vaccine significantly improved pup survival and also increased pup weights and gestation time. The gB vaccine was also more effective at decreasing viral load in dams and pups and limiting congenital transmission. Thus, rLCMV vectors that express CMV antigens may be an effective vaccine strategy for congenital CMV infection.

The role of extended preoperative steroids in hearing preservation cochlear implantation

IntroductionSteroids have been shown to reduce the hearing threshold shifts associated with cochlear implantation. Previous studies have examined only the administration of steroids just prior to surgery. The aim of this study is to examine the role of extended preoperative systemic steroids in hearing preservation cochlear implantation. MethodsAn animal model of cochlear implantation was used. 24 Hartley strain guinea pigs with a mean weight of 768 g and normal hearing were randomised into a control group, a second group receiving a single dose of systemic dexamethasone one day prior to surgery, and a third group receiving a daily dose of systemic dexamethasone for 5 days prior to surgery. A specially designed cochlear implant electrode by Med-EL (Innsbruck) was inserted through a dorsolateral approach to an insertion depth of 5 mm and left in-situ. Auditory brain stem responses at 8 kHz, 16 kHz and 32 kHz were measured preoperatively, and 1 week, 1 month and 2 months postoperatively. Cochlear histopathology was examined at the conclusion of the study. ResultsAt 1-week post operative, both groups receiving dexamethasone prior to implantation had smaller threshold shifts across all frequencies and which was significant at 32 kHz (p < 0.05). There were no differences among the three groups in the area of electrode related fibrosis. Spiral ganglion neuron (SGN) density was significantly higher in the group receiving steroids for 5 days, but only in the basal cochlear turn. DiscussionThis is study demonstrates the benefits of extended preoperative systemic steroids on hearing outcomes and SGN density in an animal model of cochlear implantation surgery.

Quantitative study of Rickettsia massiliae in Rhipicephalus sanguineus organs

Rickettsia massiliae, belonging to the spotted fever group of Rickettsia, is a human pathogen causing a similar course of disease to that caused by R. conorii, the originally recognized etiologic agent of Mediterranean spotted fever. In view of this similarity, we performed an ultrastructural study of R. massiliae in organs of Rhipicephalus sanguineus ticks, in order to advance knowledge of the complex dynamics at the tick-pathogen interface in rickettsioses.Adult R. massiliae-infected Rh. sanguineus ticks were fed on uninfected Hartley strain guinea pigs, and five females were collected daily throughout their feeding period up to day 6, and analyzed by quantitative real-time PCR and electron microscopy. An increase in rickettsial content was observed in the salivary glands, particularly in the first two days of feeding, and a plateau was observed between days 3 and 6. Rickettsial organisms were observed in all tick organs analyzed, in higher numbers in the fed state, and statistically significant differences were observed in measurements of the periplasmic layer of R. massiliae in salivary glands of fed and unfed Rh. sanguineus ticks, with increased thickness in the former case.This study provides insight into the interface between R. massiliae and Rh. sanguineus ticks, highlighting the need for analysis of R. massiliae to fully ascertain its place as an important pathogenic agent of a spotted fever rickettsiosis.

Histopathological examination of knee pain-related findings in Hartley strain guinea pigs with spontaneous osteoarthritis injection of hyaluronic acid into knee joint

Histopathological examination of knee pain-related findings in Hartley strain guinea pigs with spontaneous osteoarthritis injection of hyaluronic acid into knee joint

Rifapentine Is Not More Active than Rifampin against Chronic Tuberculosis in Guinea Pigs

Rifamycins are key sterilizing drugs in the current treatment of active tuberculosis (TB). Daily dosing of rifapentine (P), a potent rifamycin with high intracellular accumulation, in place of rifampin (R) in the standard antitubercular regimen significantly shortens the duration of treatment needed to prevent relapse in a murine model of active TB. We undertook the current study to compare directly the activities of human-equivalent doses of P and R in a guinea pig model of chronic TB, in which bacilli are predominantly extracellular within human-like necrotic granulomas. Hartley strain guinea pigs were aerosol infected with ~200 bacilli of Mycobacterium tuberculosis H37Rv, and treatment given 5 days/week was initiated 6 weeks later. R at 100 mg/kg of body weight and P at 100 mg/kg were given orally alone or in combination with isoniazid (H) at 60 mg/kg and pyrazinamide (Z) at 300 mg/kg. Culture-positive relapse was assessed in subgroups of guinea pigs after completion of 1 and 2 months of treatment. Human-equivalent doses of R and P showed equivalent bactericidal activity when used alone and in combination therapy. In guinea pigs treated with rifampin, isoniazid, and pyrazinamide (RHZ) or PHZ, microbiological relapse occurred in the lungs of 8/10 animals treated for 1 month and in 0/10 animals treated for 2 months. Substitution of P for R in the standard antitubercular regimen did not shorten the time to cure in this guinea pig model of chronic TB. Data from ongoing clinical trials comparing the activity of these two drugs are awaited to determine the relevance of the guinea pig TB model in preclinical drug screening.

Direct transplantation of mesenchymal stem cells into the knee joints of Hartley strain guinea pigs with spontaneous osteoarthritis.

IntroductionMesenchymal stem cells (MSCs) can differentiate into various connective tissue cells. Several techniques have been used for the clinical application of MSCs in articular cartilage repair; however, there are many issues associated with the selection of the scaffold material, including its ability to support cell viability and differentiation and its retention and degradation in situ. The application of MSCs via a scaffold also requires a technically demanding surgical procedure. The aim of this study was to test the outcome of intra-articular transplantation of mesenchymal stem cells suspended in hyaluronic acid (HA) in the knee joints of Hartley strain guinea pigs with spontaneous osteoarthritis (OA).MethodsCommercially available human MSCs were cultured, labeled with carboxyfluorescein diacetate succinimidyl ester (CFDA-SE), suspended in either PBS or HA, and injected into the knee joints of 7-month-old animals. The control animals were injected with either PBS or HA alone. The animals were sacrificed at 1, 3, and 5 weeks post transplantation, the knee joints harvested, and fluorescent microscopic analysis was performed. Histological and immunohistochemical analysis were performed at 5 weeks post transplantation.ResultsAt 5 weeks post transplantation, partial cartilage repair was noted in the HA-MSC group but not in the other groups. Examination of CFDA-SE-labeled cells demonstrated migration, differentiation, and proliferation of MSC in the HA-MSC group. There was strong immunostaining for type II collagen around both residual chondrocytes and transplanted MSCs in the OA cartilage.ConclusionThis scaffold-free and technically undemanding technique appears to result in the regeneration of articular cartilage in the spontaneous OA animal model. Although further examination of the long-term effects of transplantation is necessary, the findings suggest that intra-articular injection of HA-MSC mixture is potentially beneficial for OA.

Differential effects of chronic ethanol exposure on cytochrome P450 2E1 and the hypothalamic–pituitary–adrenal axis in the maternal–fetal unit of the guinea pig

BackgroundEthanol neurobehavioural teratogenicity is a leading cause of developmental mental deficiency, in which the hippocampus is a target site of injury. The multi-faceted mechanism of ethanol teratogenicity is not completely understood. This study tested the hypothesis that chronic ethanol exposure (CEE), via chronic maternal ethanol administration, increases cytochrome P450 2E1 (CYP2E1) expression and alters hypothalamic–pituitary–adrenal (HPA) axis activity in the maternal–fetal unit during the third-trimester-equivalent of gestation. MethodsPregnant Dunkin–Hartley-strain guinea pigs received daily oral administration of ethanol (4g ethanol/kg maternal body weight) or isocaloric-sucrose/pair-feeding (control) throughout gestation (term, about gestational day (GD) 68). On GD 45, 55 and 65, pregnant animals were euthanized 2h after the last daily dose. Maternal and fetal body weights and fetal hippocampal brain weight were determined. Maternal and fetal samples were collected for the determination of liver CYP2E1 enzymatic activity and plasma free cortisol and ACTH concentrations. ResultsCEE, with maternal blood ethanol concentration of 108–124mg/dl at 2h after the last dose, decreased fetal hippocampal weight only at GD 65 and had no effect on fetal body weight compared with control. CYP2E1 activity increased with gestational age in the fetal liver microsomal and mitochondrial fractions. CEE increased CYP2E1 activity in the microsomal and mitochondrial fractions of maternal liver at the three gestational ages and in both hepatic subcellular fractions of the GD 65 fetus compared with control. There was a gestational-age-dependent increase in maternal and fetal plasma free cortisol concentrations, but no effect of CEE compared with control. Maternal and fetal plasma ACTH concentrations were unaffected by CEE compared with control, and were virtually unchanged during the third-trimester-equivalent that was studied. ConclusionThese data demonstrate that, in the pregnant guinea pig, this CEE regimen increases liver CYP2E1 activity, without affecting HPA axis function, in the maternal–fetal unit during near-term gestation. The CEE-induced increase in liver CYP2E1 activity and potential oxidative stress in the maternal–fetal unit may play a role in the pathogenesis of ethanol teratogenicity.

Acetaminophen‐mediated cardioprotection: a mechanistic investigation of cytochrome c release

Considerable recent attention has been given to the potential detrimental effects of Cox-2 specific analgesics in the mammalian cardiovascular system. However, there have been few rigorous physiological investigations of the effects of other analgesics on the cardiovascular system of mammals. Acetaminophen, a popular non-NSAID analgesic in humans, has cardioprotective properties in basic laboratory investigations of ischemia/reperfusion. Although structural, functional, and biochemical evidence of the cardioprotection exists, mechanistic data are noticeably absent. Acetaminophen-mediated attenuation of apoptosis is one possible mechanism we explored to explain the reported cardioprotection. Hearts isolated from Hartley strain guinea pigs were perfused with either acetaminophen [0.35mM] or its vehicle using Langendorff techniques. They were then freeze-clamped and homogenized following baseline, ischemia, or ischemia/reperfusion. Cytosolic and whole heart homogenate samples were probed for cytochrome c to determine if there were any mitochondrial changes subsequent to treatment. Early results suggest acetaminophen-mediated inhibition of mitochondrial cytochrome c release following ischemia/reperfusion injury. This work was funded in part by Johnson & Johnson COSAT/McNeil CSP.

A comparative analysis of bone and cartilage metabolism in two strains of guinea-pig with varying degrees of naturally occurring osteoarthritis

Objective To evaluate the interaction of bone and cartilage in knee osteoarthritis (OA) pathogenesis in two guinea-pig strains with appreciable differences in bone metabolism. Design Two guinea-pig strains were evaluated for their susceptibilities to OA using semi-quantitative histological grading of knee joints and quantification of biomarkers including urinary excretion of hydroxylysyl-pyridinoline (HP) and lysyl-pyridinoline (LP) collagen cross-links, serum osteocalcin (OC), and synovial fluid levels of keratan sulfate (KS). Results At 12 months of age, Strain 13 guinea-pigs had minimal to mild histological evidence of OA compared to the Hartley strain guinea-pigs. The Hartley strain, with more severe OA, had a higher rate of bone formation (serum osteocalcin) and bone resorption (HP and LP) evident at a young age with persistence of a greater rate of bone formation at 12 months of age. The Strain 13 possessed much thicker subchondral bone at the outset (2 months) compared to the Hartley; however, the Hartley strain showed the greatest increase in subchondral bone thickness coincident with the development of cartilage degeneration. Thus, the process of subchondral bone thickening, in contrast to the absolute initial subchondral bone thickness, was a hallmark of OA in the guinea-pig. Moreover, Strain 13 had lower intraarticular proteoglycan turnover. Levels of synovial fluid keratan sulfate were positively correlated with the severity of histological OA. Conclusions This pilot study represents the first evidence of differential susceptibility to OA in guinea-pigs. Comparison of these two strains of guinea-pig has revealed that increased metabolism within the affected tissues, cartilage and bone, is associated with the development and progression of OA. This work demonstrates that the Strain 13 is a viable age-matched control to the Hartley strain and merits a more in depth evaluation of the contribution of bone and bone metabolism to OA. Copyright 2002 OsteoArthritis Research Society International. Published by Elsevier Science Ltd. All rights reserved.

Neurotoxic Mechanism of Cinnabar and Mercuric Sulfide on the Vestibulo-Ocular Reflex System of Guinea Pigs

Cinnabar, a naturally occurring mercuric sulfide (HgS), has been combined with Chinese herbal medicine as a sedative for more than 2000 years. To date, its neurotoxic effect on the vestibulo-ocular reflex (VOR) system has not been reported. By means of a caloric test coupled with electronystagmographic recordings, the effect of commercial HgS and cinnabar on the VOR system of guinea pigs was studied. HgS or cinnabar was administered orally (1.0 g/kg) to Hartley-strain guinea pigs once daily for 7 consecutive days. A battery of electrophysiological, biochemical, and histopathological examinations were performed. The results showed that HgS induced a 60% caloric response abnormality (40% caloric hyperfunction and 20% hypofunction), whereas the abnormal responses appeared to be more severe (six out of six) in the cinnabar group. The Hg contents of whole blood and cerebellum were increased and correlated to their neurotoxic effects on the VOR system, indicating that both insoluble HgS and cinnabar could be absorbed from the gastrointestinal tract and distributed to the cerebellum. Although the vestibular labyrinth revealed no remarkable change under light microscopy, loss of Purkinje cells in the cerebellum was detected, and the enzymatic Na(+)/K(+)-ATPase activity of cerebellum (a higher inhibitory center of the VOR system) was significantly inhibited by HgS and cinnabar. Moreover, cerebellar nitric oxide (NO) production was increased significantly. Hence, we tentatively conclude that the increased Hg contents in the cerebellum following oral administration of HgS and cinnabar were responsible, at least in part, for the detrimental neurotoxic effect on the VOR system. Potentially, decreasing Na(+)/K(+)-ATPase activity and increasing NO production within the cerebellar regulatory center are postulated to mediate this VOR dysfunction caused by the mercurial compounds and cinnabar.

Toxic Effects of Potassium Bromate and Thioglycolate on Vestibuloocular Reflex Systems of Guinea Pigs and Humans

Potassium bromate (KBrO3) and thioglycolate are two components of hair curling solution. The neurotoxic effects of KBrO3 and thioglycolate on the vestibuloocular reflex (VOR) system have not been elucidated. In this paper, we report the adverse effects of KBrO3 and thioglycolate on the VOR system of Hartley-strain guinea pigs. The function of the VOR system was evaluated by caloric test coupled with the electronystagmographic recordings after subcutaneous injection of 20 or 50 mg/kg KBrO3 or 15 mg/kg thioglycolate, either alone or in combination once daily for 14 consecutive days. The results showed that KBrO3 produced abnormal caloric responses in a concentration-dependent manner and thioglycolate enhanced this abnormality. Our clinical patients, 10 female hairdressers exposed to the hair curling solution for 10–30 years revealed a similar dysfunction in the caloric test. The possible mechanism of this adverse effect was studied: the cerebellar-regulated functions such as motor equilibrium performance and spontaneous locomotor activity of guinea pigs were reduced, the enzymatic Na+/K+-ATPase and Ca2+-ATPase activities of cerebellar tissues were significantly decreased, and the loss of Purkinje cells as well as the derangement of the granular cell layer of the cerebellar cortex was revealed after treatment with KBrO3 plus thioglycolate. These findings imply that KBrO3 plus thioglycolate is toxic to the VOR system, mediated by, at least in part, the dysfunction of a higher cerebellar regulatory mechanism. We suggest that the caloric test is a noninvasive method for monitoring the consequences of hazardous exposure of hair curling solution in humans. Our clinical findings together with the animal study imply that clinicians should be alert to the risk of bromate exposure in hairdressers, especially those with vertigo, tinnitus, or hearing loss.

Elevating dietary salt exacerbates hyperpnea-induced airway obstruction in guinea pigs

Previous studies have indicated that increased dietary salt consumption worsens postexercise pulmonary function in humans with exercise-induced asthma (EIA). It has been suggested that EIA and hyperpnea-induced airway obstruction (HIAO) in guinea pigs (an animal model of EIA) are mediated by similar mechanisms. Therefore, the purpose of this study was to determine whether altering dietary salt consumption also exacerbated HIAO in guinea pigs. Furthermore, the potential pathway of action of dietary salt was investigated by blocking leukotriene (LT) production during HIAO in guinea pigs. Thirty-two male Hartley strain guinea pigs were split into two groups. One group (n = 16) of animals ingested a normal-salt diet (NSD) for 2 wk; the other group (n = 16) ingested a high-salt diet (HSD) for 2 wk. Thereafter, animals were anesthetized, cannulated, tracheotomized, and mechanically ventilated during a baseline period and during two dry gas hyperpnea challenges. After the first challenge, the animals were administered either saline or nordihydroguaiaretic acid, a LT inhibitor. Bladder urine was analyzed for electrolyte concentrations and urinary LTE(4). The HSD elicited higher airway inspiratory pressures (Ptr) than the NSD (P < 0.001) postchallenge. However, after infusion of the LT inhibitor and a second hyperpnea challenge, HIAO was blocked in both diet groups (P < 0.001). Nonetheless, the HSD group continued to demonstrate slightly higher Ptr than the NSD group (P < 0.05). Urinary LTE(4) excretion significantly increased in the HSD group compared with the NSD group within treatment groups. This study has demonstrated that dietary salt loading exacerbated the development of HIAO in guinea pigs and that LT release was involved in HIAO and may be moderated by changes in dietary salt loading.

DIETARY SALT CONSUMPTION AND LEUKOTRIENE-DEPENDENT HYPERPNEA-INDUCED AIRWAY OBSTRUCTION IN GUINEA PIGS

The purpose of this study was to determine if altering dietary salt consumption moderates hyperpnea-induced airway obstruction (HIAO) in guinea pigs (an animal model of exercise-induced asthma), and to determine whether blocking leukotriene (LT) biosynthesis alters the airway response to hyperpnea on the different salt diets. Thirty-two male Hartley strain guinea pigs were split into two groups. One group (n = 16) of animals ingested a normal salt diet (NSD) for 2 weeks, while the other group (n = 16) ingested a high salt diet (HSD) for two weeks. Thereafter, animals were anesthetized, cannulated, tracheotomized, and mechanically ventilated during a baseline period and during a dry gas hyperpnea challenge. After the hyperpnea challenge, baseline ventilator settings were resumed and animals were administered either saline [NSD- CON (n = 8) and HSD-CON (n = 8)], or NDGA, a LT inhibitor [NSD-BLO (n = 8) and HSD-BLO (n = 8)]. Subsequently, a second hyperpnea challenge was followed by a second post-hyperpnea recovery period. Airway inspiratory pressures (Ptr) were monitored continiously Bladder urine was collected by needle aspiration after euthanasia, and analyzed for urinary concentrations of sodium, chloride, potassium and creatinine. There were no significant differences between the NSD and HSD diet for Ptr prior to the first hyperpnea challenge (p > 0.05). However, the HSD elicited higher Ptr than the NSD (p < 0.001) post-challenge. Following infusion of saline (CON), and a second hyperpnea challenge, the HSD-CON group demonstrated higher Ptr than the NSD diet group (p < 0.001). However, following infusion of the LT-inhibitor, and a second hyperpnea challenge, HIAO was attenuated in both the NSD-BLO and HSD-BLO groups compared to the CON groups respectively (p < 0.001). Nonetheless, the HSD-BLO group continued to demonstrate higher Ptr than the NSD-BLO group (p < 0.05). Conclusion: This study has demonstrated that dietary salt loading exacerbates the development of HIAO in guinea pigs, and that LT release is involved in HIAO and may be moderated by changes in dietary salt loading. (Supported by the College Research Council, College of Veterinary Medicine and Biomedical Sciences, Colorado State University)

Effects of growth factors and cytokines on proteoglycan and collagen synthesis by chondrocytes in guinea pigs with spontaneous osteoarthritis

We examined the effects of various growth factors and cytokines on proteoglycan (PG) and collagen synthesis by chondrocytes isolated from osteoarthritic and normal articular cartilage of Hartley strain guinea pigs. The guinea pig represents a useful animal model of spontaneous osteoarthritis (OA). Cartilage tissue samples were obtained from the knee joints of under-3-month-old guinea pigs (control group) as well as 5- to 8-month-old guinea pigs with OA changes (OA group). Chondrocytes were isolated enzymatically and maintained in suspension culture. Growth factor addition groups were then prepared from both the OA group and the control group, using the factors TGF-β, bFGF, and IGF-1 (1.25 ng/ml each). Cytokine addition groups were also prepared using IL-1α and IL-1β (10 ng/ml each). An addition group was also prepared for sodium hyaluronate (HA) (500 μg/ml). In each group, 35S was added as a PG metabolic marker, 3H-proline was added as a collagen metabolic marker, and the groups were cultured. Next, 35S and 3H-proline uptake was measured by a liquid scintillation counter. The results revealed that (1) both PG synthesis and collagen synthesis were promoted significantly more in OA chondrocytes than in normal chondrocytes; (2) with the addition of growth factors, PG and collagen synthesis was enhanced in OA chondrocytes; and (3) PG synthesis and collagen synthesis were inhibited in both normal and OA chondrocytes with the addition of IL-1α and -β. This result suggests that the repair function is activated more in OA chondrocytes than in normal chondrocytes, thereby promoting the synthesis of the cartilage matrix by chondrocytes. This synthesizing capability is enhanced and acts to effectively repair degenerative articular cartilage further through the addition of growth factors.

PKC translocation without changes in Galphaq and PLC-beta protein abundance in cardiac hypertrophy and failure.

Activation of protein kinase C (PKC) has been implicated as playing a key role in the pathogenesis of cardiac hypertrophy. This study investigates the response of several signal transduction proteins responsible for PKC activation during the transition from compensated pressure-overload hypertrophy (POH) to congestive heart failure (CHF). Pressure overload was produced on male, adult, Hartley strain guinea pigs using a ligature around the descending thoracic aorta. Sham-operated controls, POH, and CHF groups were identified based on left ventricular hypertrophy, pulmonary congestion, and isolated heart Langendorff mechanics. Quantitative immunoblotting revealed phospholipase C (PLC)-betaI and Galphaq were unchanged during POH and CHF, as were RGS2, RGS3, and RGS4 (regulators of G protein signaling, which are activators of intrinsic GTPase activity). Translocation of PKC-alpha, -epsilon, and -gamma from cytosolic to membranous fractions were significantly increased during POH and CHF. Cytosolic PKC activity was also elevated during POH. We conclude that differential PKC activation may be mediated by increases in Galphaq and PLC-betaI activity rather than upregulation of expression.

Bone remodeling in osteoarthritis: subchondral and osteophytic responses

OSTEOARTHRITIS can be considered a collective endstage for heterogeneous etiopathologic conditions a#ecting joint tissues. Such etiopathologic factors are multifactorial and include biochemical, enzymatic, genetic and biomechanical factors amongst others. Characteristic pathologic findings include joint space narrowing, peripheral osteophytes, subchondral bony sclerosis and cyst formation. Although commonly considered a disease primarily involving cartilage, studies support variable roles for synovium, muscle, ligaments and bone. Radin and co-workers [1, 2] suggested an important role for subchondral bone changes as an etiologic factor in the early development of degenerative joint disease. Repetitive impulsive loading resulted in early responses characterized by increased bone formation, associated with relative sti#ening of bone; articular cartilage degeneration followed [3]. Subchondral bone changes preceding cartilage damage in osteoarthritis have been demonstrated in other animal models. Examination of trabecular bone within the femoral head of Hartley strain guinea pigs, a strain predisposed to osteoarthritis, demonstrated subchondral trabecular remodeling as an early event in this model of OA [4]. Serial observations in this model utilizing magnetic resonance imaging revealed significant progression of subchondral sclerosis as well as osteophytes during disease development [5]. A longitudinal study of subchondral bone responses in dogs undergoing anterior cruciate ligament transection revealed subchondral sclerosis at 18 months and 54 months, but not at 3 months; findings were associated with loss of subchondral trabecular bone at all three time points. Findings suggested that bony changes were associated with progression of cartilage degeneration, rather than initial development [6]. Experimentally induced osteoarthritis following partial meniscectomy (PM) in the rabbit was associated with prominent osteophyte formation [7]. Increased cellular replication was noted early (at

Superoxide mediates cigarette smoke-induced infiltration of neutrophils into the airways through nuclear factor-kappaB activation and IL-8 mRNA expression in guinea pigs in vivo.

We examined the hypothesis that superoxide mediates infiltration of neutrophils to the airways through nuclear factor (NF)-kappaB and interleukin-8 (IL-8) after acute exposure to cigarette smoke (CS) in vivo. Male Hartley strain guinea pigs were exposed to air or 20 puffs of CS and killed 5 h after the exposure. The differential cell count of bronchoalveolar lavage fluid and specific myeloperoxidase enzyme assay demonstrated that acute exposure to CS caused neutrophil accumulation to the airways and parenchyma, respectively. Acute exposure to CS increased DNA-binding activity of NF-kappaB in the lung. Acute exposure to CS also increased IL-8 messenger RNA (mRNA) expression in the lung. Pretreatment of guinea pigs with recombinant human superoxide dismutase (rhSOD) aerosols reduced the CS-induced neutrophil accumulation to the airways. Both activation of NF-kappaB and increased IL-8 mRNA expression were also inhibited by the pretreatment of rhSOD aerosols. Strong immunoreactivities for p65 and p50 were detected in the nuclei of alveolar macrophages after acute exposure to CS. The signal for IL-8 mRNA expression was demonstrated in the alveolar space after acute exposure to CS. Neither significant immunoreactivities for p65 and p50 nor IL-8 mRNA signals were observed in airway epithelium. These observations suggest that acute exposure to CS initiates superoxide-dependent mechanism that, through NF-kappaB activation and IL-8 mRNA expression, produces infiltration of neutrophils to the airways in vivo. It was also suggested that the alveolar macrophage is one potential source of NF-kappaB activation and IL-8 mRNA expression after acute exposure to CS.

Roles of oxygen radicals and elastase in citric acid-induced airway constriction of guinea-pigs.

Antioxidants attenuate noncholinergic airway constriction. To further investigate the relationship between tachykinin-mediated airway constriction and oxygen radicals, we explored citric acid-induced bronchial constriction in 48 young Hartley strain guinea-pigs, divided into six groups: control; citric acid; hexa(sulphobutyl)fullerenes + citric acid; hexa(sulphobutyl)fullerenes + phosphoramidon + citric acid; dimethylthiourea (DMTU) + citric acid; and DMTU + phosphoramidon + citric acid. Hexa(sulphobutyl)fullerenes and DMTU are scavengers of oxygen radicals while phosphoramidon is an inhibitor of the major degradation enzyme for tachykinins. Animals were anaesthetized, paralyzed, and artificially ventilated. Each animal was given 50 breaths of 4 ml saline or citric acid aerosol. We measured dynamic respiratory compliance (Crs), forced expiratory volume in 0.1 (FEV0.1), and maximal expiratory flow at 30% total lung capacity (Vmax30) to evaluate the degree of airway constriction. Citric acid, but not saline, aerosol inhalation caused marked decreases in Crs, FEV0.1 and Vmax30, indicating marked airway constriction. This constriction was significantly attenuated by either hexa(sulphobutyl)fullerenes or by DMTU. In addition, phosphoramidon significantly reversed the attenuating action of hexa(sulphobutyl)fullerenes, but not that of DMTU. Citric acid aerosol inhalation caused increases in both lucigenin- and t-butyl hydroperoxide-initiated chemiluminescence counts, indicating citric acid-induced increase in oxygen radicals and decrease in antioxidants in bronchoalveolar lavage fluid. These alterations were significantly suppressed by either hexa(sulphobutyl)fullerenes or DMTU. An elastase inhibitor eglin-c also significantly attenuated citric acid-induced airway constriction, indicating the contributing role of elastase in this type of constriction. We conclude that both oxygen radicals and elastase play an important role in tachykinin-mediated, citric acid-induced airway constriction.

An animal model of autism: behavioural studies in the GS guinea-pig

Autism is a human behavioural pathology marked by major difficulties in abnormal socialization, language comprehension and stereotypic motor patterns. These behavioural abnormalities have been associated with corticocerebral and cerebellar abnormalities in autistic patients, particularly in vermal folia VI and VII. Progress in understanding this disease has been hindered by the absence of a non-primate animal model. GS guinea-pigs are a partially inbred, non-ataxic guinea-pig strain with cerebellar and corticocerebral abnormalities similar to those reported to exist in human patients with autism. In order to determine if GS guinea-pigs represent an animal model of autism, their behaviour was compared with that of Hartley strain guinea-pigs. GS animals learned a motor task significantly more rapidly than Hartley guinea-pigs, but performed it in a more stereotypic manner and were less influenced by environmental stimuli than Hartleys. GS animals exhibited significantly less exploratory behaviour in a novel environment and were significantly less responsive to 50–95 dBA pure tones than Hartley guinea-pigs. In a social interaction assay, GS guinea-pigs interacted significantly less frequently with each other or with Hartley guinea-pigs than Hartleys did under the same conditions. GS behaviour thus exhibits autistic-like behaviour patterns: motor stereotypy, lack of exploration and response to environment and poor social interaction. Coupled with the neuropathological findings, this abnormal behaviour suggests that GS guinea-pigs could be a useful animal model of autism.