Prevalence of intestinal parasites and profile of CD4+ counts in HIV+/AIDS people in north of Iran, 2007-2008

In this study 142 stool samples (64 HIV+/AIDS patients and 78 non-HIV infected individuals) collected from Mazandaran province and screened for intestinal parasites, using direct wet mont, formalin-ether sedimentation concentration, modified Ziehl Neelsen and modified trichrome techniques. Each person in this study was examined for CD4+ counts. Intestinal parasites were found in 11/64 (17.2%) of patients in HIV+/AIDS group and in 14/78 (17.9%) of controls. Prevalence of parasites detected in HIV+/AIDS individuals was as follow: Cryptosporidium sp. 9.4%, Giardia lamblia 3.1%, Entamoeba coli 1.6%, E. histolytica 1.6% and Chilomastix mesnili 1.6%. Prevalence of parasites in controls was as follow: Trichostrongylus sp. 6.4%, G. lamblia 3.8%, Cryptosporidium sp. 2.5%, E. coli 2.5%, E. histolytica 1.2%, Hookworms 1.2%. The mean of CD4+ counts in HIV-positive group (430 cells microL(-1)) was remarkedly less than controls (871 cells microL(-1)) (p = 0.001). As patients usually belong to poor socio-economic backgrounds and they can hardly afford treatment, therefore, it is suggested screening and free treatment of intestinal parasites in these individuals should be taken by health centers to prevent the occurrence of these diseases in HIV+/AIDS patients, as often the disease may take a fulminant form.

Variations in chondrocyte apoptosis may explain the increased prevalence of osteoarthritis in some joints

OBJECTIVES

To investigate whether there are any variations in chondrocyte susceptibility to an apoptotic stimulus between cells of articular cartilage (AC) from equine joints that differ in prevalence of osteoarthritis (OA).

METHODS

Cartilage from macroscopically normal equine metacarpophalangeal (MCP), proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints was used. Prior to culture, chondrocyte viability was assessed using the fluorescein diacetate (FDA) and propidium iodide paravital staining method. AC explants were subsequently treated with tumour necrosis factor-α (TNF-α) in combination with Actinomycin D to induce apoptosis. Apoptosis of chondrocytes in cartilage sections was assessed by expression of active caspase-3 using indirect immunohistochemistry and sections also histologically graded using a 'modified' Mankin scoring system.

RESULTS

Prior to culture (mean ± standard deviation) chondrocyte viability was 80.7% (3.5). The extent of chondrocyte apoptosis induced by TNF-α/Actinomycin D varied markedly according to the joint type that the cartilage was sampled from. For MCP joints, the extent of overall chondrocyte apoptosis was significantly higher (P < 0.001) in stimulated explants (26.7%, 10.3) than that observed in unstimulated control samples (9.6%, 7.5). Conversely, chondrocytes from PIP and DIP joint cartilage did not respond significantly to apoptotic stimulation (P > 0.05). Significant variations in cellularity and thickness were also evident between cartilages of different joint types.

CONCLUSIONS

Data in this study demonstrate that chondrocytes from three equine joint types with varying prevalences of OA differ significantly in terms of susceptibility to apoptosis induction. This may provide a possible explanation for the joint-specific nature of the disease.

Seroprevalence of toxocariasis in schoolchildren in Northern Iran

This cross-sectional study was carried out on 1210 randomly selected schoolchildren, attending sixteen primary and secondary schools, during the period between November 2005 and June 2006. Parents who accepted to include their children were requested to be present at sampling time and to fill in a simple questionnaire with personal and epidemiological data. Three milliliter of venous blood were taken by vein puncture under sterile conditions from each subject for detection and titration of antibodies to T. canis and eosinophil counts. Total IgG anti-Toxocara antibodies was evaluated by T. canis IgG ELISA kit. According to the manufacture recommendations, an index positivity >11 U was considered positive. Of the 1210 serum specimens tested, an overall seroprevalence for Toxocara antibodies of 25% was obtained. There was no association between positive seroprevalence and age (p = 0.34). Boys and girls differed significantly with regard to Toxocra titre (p = 0.003). Eosinophilia in peripheral blood (> or = 5%) was detected in 24.5% (297/1210) of the population studied, 97/297 (32.8%) of whom were seropositive for toxocariasis. The findings of this study confirmed that infection with Toxocara is quite high and widespread in children in Northern Iran. Therefore, health promotion efforts must be directed at increasing the awareness of the population about the potential zoonotic hazards associated with the disease and how to minimize them.

Prevalence of Toxocara canis in stray dogs, northern Iran

Toxocara canis is one of the most common parasites living in the intestine of domestic and stray dogs. A dog eliminates thousands of eggs into the environment that are potential etiological factor for human toxocariasis. The present study was undertaken to determine the prevalence of T. canis in stray dogs in Mazandaran, Iran. In this cross-sectional study, during the period from April to September 2007, 50 young and adult stray dogs were collected by shooting from urban areas of Sari city, Northern Iran. They were necropsied and the gastrointestinal tract was opened. Recovered parasites were fixed in alcohol and stained in carmine. Faecal specimens were also examined by the formalin ether concentration method. A total of 27 adult and 23 young dogs were examined with 11 adults (40.7%) and 19 youngs (82.6%) being infected with T. canis with an overall prevalence of 60%. There were significant differences in the prevalence of infection between adult and young dogs (p = 0.003). There were no significant differences in the prevalence of infection between male and female dogs (p > 0.05). Considering the high prevalence of this zoonotic parasite and its hygienic significance in causing human toxocariasis, particularly in children, plus the lack of control of stray dog populations, there is a need to improve personal and food hygiene as well controlling stray dogs in these urban

Frequency of HBV, HCV and HIV infections among hospitalized injecting drug users in Kashan

Context:

Infectious diseases including HIV and viral hepatitis constitute a major health issue, with high prevalence among injecting drug users (IDUs).

Aims:

The present study assessed the frequency of HIV, and hepatitis B and C viruses (HBV and HCV) among 200 IDUs, hospitalized between 2001 and 2006, in Shahid Beheshti Hospital of Kashan, Iran.

Setting and Design:

A population-based cross-sectional study in Iran.

Materials and Methods:

A total of 200 subjects participated in this study. Serological markers including HBsAg, anti-HCV antibodies and HIV were assessed by ELISA method using Monobid kits made in US. Demographic data was collected by using a questionnaire, which was designed by a researcher.

Statistical Analysis Used:

Frequencies were determined by employing SPSS:PC version 15.0, and Chi-square and Fisher's exact tests were used to compare proportions.

Results:

The mean age of subjects was 36.5 ± 10.2 years. Approximately 88.5% (177 cases) were male and 11.5%. (23 cases) were female. The frequency of positive infection test results for males with respect to HBV, HCV, and HIV was 4% (8 cases), 10.5% (21 cases), and 1.5% (3 cases); and for females it was 0.5% (1 case), 1.5% (3 cases), and 0% (0 case), respectively.

Conclusion:

This study demonstrates that the frequency of HBV, HCV, and HIV infection in the IVD user in Kashan, Iran, is relatively high and this condition is more serious in male than female drug addicts. It is very important, especially for health providers and policy makers, to recognize the risk factors of HBV, HCV and particularly HIV infection in this area and design effective preventive programs.

Can biochemical markers serve as surrogates for imaging in knee osteoarthritis?

OBJECTIVE

Osteoarthritis (OA) is a complex heterogeneous joint disease affecting more than 35 million people worldwide. The current gold standard diagnostic investigation is the plain radiograph, which lacks sensitivity. Biochemical markers have the potential to act as adjunct markers for imaging in the assessment of knee OA. We undertook this study to determine the association between individual biochemical markers and radiographic features, and to establish whether the association is strengthened when selected biochemical markers are combined into a single factor (a theoretical marker).

METHODS

Twenty serum and urinary biochemical markers were analyzed in 119 patients with predominantly tibiofemoral knee OA. Pearson's correlation was performed, and corresponding coefficients of determination (R(2)) were calculated to determine the association between biochemical markers and a range of imaging features from radiographs and dual x-ray absorptiometry of the knee. Biochemical markers demonstrating a significant association (P < 0.05) with a specific imaging feature were combined by principal components analysis (PCA). Pearson's correlation was repeated to establish whether the combined panel of biochemical markers showed a stronger association with imaging than the best single marker.

RESULTS

Fourteen biochemical markers showed significant associations with one or more imaging features. By combining specific panels of biochemical markers to form factors, the association of markers with imaging features (R(2)) increased from 11.9% to 22.7% for the Kellgren/Lawrence (K/L) score, from 5.9% to 9.2% for joint space width (JSW), from 6.6% to 10.8% for sclerosis, from 13.5% to 22.6% for osteophytes, and from 12.0% to 14.2% for bone mineral density (BMD). Biochemical markers identifying patients with osteophytes overlapped with those correlated with a high K/L score, while markers of subchondral BMD formed a completely separate group. Biochemical markers of JSW included markers associated with both osteophytes and BMD.

CONCLUSION

The PCA results suggest that biochemical marker combinations may be more sensitive than individual biochemical markers for reflecting structural damage in patients with knee OA. The differences in biochemical marker profiles associated with osteophytes compared with those associated with subchondral BMD raise the possibility that these 2 processes, commonly seen in bone in knee OA, have underlying biologic differences.

Seroprevalence of Toxoplasma gondii in cattle, sheep and goats slaughtered for food in Mazandaran province, Iran, during 2005

Serum samples from 290 cattle, 400 goats and 588 sheep slaughtered for food in various areas of the Mazandaran province, Iran were tested for antibodies to Toxoplasma gondii by the indirect immunofluorescence antibody test (IFAT), from December 2004 to April 2005. Antibodies to T. gondii were found in 30% (120/400) goats and 35% (206/588) sheep and 0% (0/290) cattle, at a dilution of 1:16 or more for goats and sheep and 1:128 or more for cattle. The highest titres observed in cattle, goats and sheep were 1:64 (0.7%), 1:128 (1%), 1:64 (2%), respectively. These results indicate that T. gondii antibodies are widespread in the animal populations and suggest that toxoplasmosis is a widely spread zoonotic infection in northern Iran.

Effect of foliar application of micronutrients on the yield and quality of sweet orange (Citrus Sinensis L.)

An experiment was designed to study the effect of foliar application of micronutrients on the yield, quality and leaf composition of sweet orange, Blood red variety at Shabazgari, Mardan. The experiment was laid out in a randomized complete block design in 2) factorial arrangement. Zinc, manganese and boron were applied as foliar spray at the rate of 0.4, 0.2 and 0.04 kg ha(-1), respectively in the presence of 1.56 kg N ha(-1) as urea and 0.4 kg surfactance ha(-1) (as wetting agent) in 400 L of water. The maximum fruit yield was obtained, when 0.4 kg Zn ha(-1) and 0.2 kg Mn ha(-1) was sprayed along with 1.56 kg N ha(-1) and 0.4 kg surfactance ha(-1) in 400 L of water. The minimum % peel was obtained with B alone and minimum % rag with Zn + Mn, maximum fruit size with Zn + B and maximum fruit volume with Zn + Mn. Similarly, % juice in sweet oranges was increased significantly by B alone, reducing sugar by Mn alone and vitamin C contents by Zn + B through foliar spray, suggested that each micronutrient had different role on the quality of citrus fruit. Foliar spray of Zn, Mn and B along with urea significantly increased the concentration of Zn and Mn in citrus leaves, while the concentration of B was not affected with foliar spray, perhaps due to dilution within the citrus tissues. Therefore, it is suggested that either Zn+Mn or Zn+B may be applied as foliar spray in combination with urea and surfactance for getting the maximum yield and improved quality of citrus fruit under prevailing conditions.

Seroepidemiological study of toxoplasmosis in intellectual disability children in rehabilitation centers of northern Iran

Serological studies revealed that toxoplasmosis has world wide distribution. Although the infection by Toxoplasma gondii is widely prevalent in humans and animals, the disease is uncommon and most of the acquired infections are asymptomatic. The important aspect of this parasitic infection is the probable danger of congenital transmission and its severe effects on the fetus. There have been many reports about the prevalence of anti-T. gondii antibody among different groups of people in Iran; however the epidemiological data in intellectual disability (ID) persons are rare. This study was performed to evaluate the seroprevalence of toxoplasmosis among the inhabitants of rehabilitation centers of northern Iran. A total of 336 serum samples (161 males, 175 females) were examined for the IgG antibodies by indirect immunofluorescense technique. First of all, 1:50 titer dilution was tested, in the cases of positive result, further dilutions (1:100, 1:200, 1:400, 1:800, 1:1600, and 1:3200) were prepared and the last dilution was recorded. Among 336 sera, 77.4% showed seropositivity by IFAT. The positive rates of males and females were 77.6% (125/161) and 80% (140/175), respectively. However, there were no significant differences between sexes. Comparing the age groups, the highest seropositive rate showed in 19 or higher, and their rates had a tendency to increase with age. Prevalence of the infection in 10 rehabilitation centers was not significant either. Nevertheless, our data (77.4%) in rehabilitation centers in northern Iran suggest that infection is the same as in many other reports in normal population in this area, therefore toxoplasmosis is not a major problem in rehabilitation centers of this geographical area.

A 5-yr longitudinal study of type IIA collagen synthesis and total type II collagen degradation in patients with knee osteoarthritis--association with disease progression

OBJECTIVES

The 5-yr longitudinal study tested the hypothesis that serum and urinary markers of type II collagen metabolism would be associated with radiological progression of disease in patients with mild-to-moderate knee osteoarthritis (OA).

METHODS

Synthesis of type IIA collagen and degradation of total type II collagen were assessed in 135 patients with mild-to-moderate knee OA over 5 yrs using serum concentration of the N-propeptide of collagen type IIA (PIIANP) and urinary excretion of crosslinked C-telopeptide (CTX-II), respectively. The markers were measured at baseline, 2, 3 and 5 yrs' follow-up corresponding to X-ray time points. Analysis of variance (ANOVA) was performed to determine longitudinal changes over 5 yrs in the biomarkers in all patients and between progressors and non-progressors.

RESULTS

Complete X-ray progression data over 5 yrs, serum PIIANP and urinary CTX-II were available for 84/135 patients. There were 24 progressors and 60 non-progressors. Overall, over the 5-yr study period average PIIANP and CTX-II levels were higher in progressors compared with non-progressors (P < 0.05 for both, ANOVA). The patients with serum PIIANP in the highest quartile of 5-yr levels of PIIANP had a significantly higher risk of progression than the other patients [relative risk (95% CI): 3.2 (1.1-9.2)]. Increased levels of urinary CTX-II were also associated with a higher risk of progression with a relative risk (95% CI) of 3.4 (1.2-9.4) in patients with 5-yr levels above the median. The risk of progression was highest in patients with 5-yr levels of PIIANP in the highest quartile and/or CTX-II in the two highest quartiles with a relative risk (95% CI) of progression, 11.8 (2.5-54).

CONCLUSIONS

The data presented here suggest that progression of knee OA is associated with alterations of systemic levels of biological markers of type II collagen metabolism. The data also suggest that the combined measurement of serum PIIANP and urinary CTX-II may be useful to identify patients with knee OA at increased risk of disease progression.

Toxocara catiinfections in stray cats in northern Iran

A cross-sectional survey was undertaken to study the prevalence and intensity of infection withToxocara catiin 100 stray cats, from April to October 2004 in urban areas of Sari, northern Iran. A total of 44 cats (44%) were found to be infected withT. cati. There was a significant difference in the prevalence of infection relative to host age and weight (P = 0.000). There was also a significant difference in the intensity of infection relative to body weight and urban sites (P < 0.05). No significant difference was found between the prevalence of infection relative to host gender, urban sites and season (P>0.05), nor in the intensity of infection between host gender, age and season (P>0.05). The intensity of infection ranged from 1 to 32 worms per cat, with a mean of 7.30 ± 6.82.

The prevalence, intensity and viability of hydatid cysts in slaughtered animals in the Ardabil province of Northwest Iran

In a cross-sectional study, a total of 5381 slaughtered animals, namely 928 cattle, 243 buffaloes, 3765 sheep and 445 goats were inspected macroscopically for hydatid cysts in northwest Iran, with prevalence values of 38.3%, 11.9%, 74.4% and 20%, respectively, being recorded. Prevalences were higher in females compared with males, but a significant difference (P < 0.001) was only found in sheep and cattle. Most cases which were condemned were seen in the lungs of sheep (13.4%) indicating that sheep are the most important intermediate hosts for Echinococcus granulosus in this area.

Chondrocyte death by apoptosis is associated with cartilage matrix degradation

OBJECTIVES

To investigate the frequency of chondrocyte apoptosis in equine articular cartilage (AC) specimens and to examine the relationship between the process of cell death and the degree of cartilage degradation using a direct quantification of numbers of apoptotic cells and expression of active caspase-3.

METHODS

AC from equine metacarpophalangeal (MCP), proximal interphalangeal (PIP) and distal interphalangeal (DIP) joints was used and each joint was graded macroscopically for cartilage degradation (macroscopic osteoarthritis (OA) score). Cartilage sections were graded using a 'modified' Mankin scoring system. Apoptosis of chondrocytes in cartilage sections was assessed morphologically by appearance of apoptotic features (direct method) and by expression of active caspase-3 using indirect immunohistochemistry.

RESULTS

The extent of apoptosis assessed by the direct method did not show any relationship with increasing severity of OA (P=0.72). However, there was a significant positive correlation between 'modified' Mankin score and apoptosis determined by caspase-3, with the extent of apoptosis found to increase linearly with increasing severity of OA (r=0.44, P=0.0043). Caspase-3 expression was found to be significantly higher in the superficial and middle zones than in the deep zone (P<0.001). In the superficial, middle and deep zones, expression of caspase-3 was significantly higher in the MCP joint than in the PIP joint (P=0.013, P=0.0018 and P=0.029, respectively). Within the MCP joints, apoptosis was higher in the lateral compartment compared to the medial (P=0.053).

CONCLUSIONS

The data presented in this study demonstrate that chondrocyte apoptosis is positively associated with degree of cartilage matrix damage and that the extent of apoptosis varies with cartilage zones and mechanical loading environment of the joint.

Clear cell trichoblastomas in two dogs

Two cases of clear cell trichoblastomas were diagnosed in young dogs. The tumour had ribbons of basaloid cells as seen in ribbon trichoblastomas, as well as differentiation to external root sheath of the hair follicle and few cells with sebaceous differentiation. This is the first report of clear cell trichoblastoma in dogs.

Serum cartilage oligomeric matrix protein and other biomarker profiles in tibiofemoral and patellofemoral osteoarthritis of the knee

OBJECTIVES

There is some evidence that tibiofemoral osteoarthritis (TFJ OA) and patellofemoral osteoarthritis (PFJ OA) may have different risk factors. To investigate the possibility that these conditions are separate disease entities, we compared biomarker profiles of patients with each disease.

METHODS

Serum samples were taken from 222 patients who had knee pain and X-ray signs of knee OA. Eighty-two had only medial TFJ OA and 38 only PFJ OA in one or both knees. The remaining patients had either mixed disease or equivocal radiographic evidence of OA. The following biomarkers were measured in serum samples from baseline and follow-up visits: cartilage oligomeric matrix protein (COMP), glycosaminoglycan, keratan sulphate epitope 5D4, YKL-40, osteocalcin, C-telopeptide of type I collagen, hyaluronan and C-reactive protein.

RESULTS

The two subsets of OA (TFJ and PFJ) had similar radiographic disease severity and there were no significant differences in the presence and patterns of pain scores (visual analogue scale and Western Ontario and McMaster Universities Osteoarthritis Index). No difference was found for the biomarkers between the two groups, with one exception. Both baseline and area under the curve per month COMP concentrations were significantly higher in the TFJ than the PFJ group (P<0.01).

CONCLUSIONS

The reduced serum COMP in PFJ disease compared with TFJ OA could be due to small articular cartilage volume in the latter or to a qualitative difference in cartilage metabolism.

Dual-energy X-ray absorptiometry applied to the assessment of tibial subchondral bone mineral density in osteoarthritis of the knee

OBJECTIVE

Plain X-ray is an imprecise tool for monitoring the subchondral bony changes associated with the development of knee osteoarthritis (OA). Our objective was to develop and validate a technique for assessing tibial subchondral bone density (BMD) in knee OA using dual energy X-ray absorptiometry (DXA).

DESIGN

Patients with OA of at least one knee underwent DXA scanning of both knees. Regions of interest (ROI) were placed in the lateral and medial compartments of tibial subchondral bone. Weight-bearing plain X-rays and Te (99m) scintiscans of both knees were obtained and scored.

RESULTS

One hundred and twelve patients (223 knees) underwent DXA and radiography. Intra-observer CV% was 2.4% and 1.0% for the medial and lateral ROI respectively. Definite OA (Kellgren and Lawrence Grade 2, 3 or 4) was correlated with age-related preservation of subchondral BMD compared to radiographically normal knees. Raised BMD was also associated with subchondral sclerosis, and positive scintigraphy.

CONCLUSION

DXA may provide a safe, rapid and reliable means of assessing knee OA. Cross-sectional age-related subchondral tibial BMD loss is attenuated by knee OA.

Serum YKL-40 concentrations in patients with early rheumatoid arthritis: relation to joint destruction

OBJECTIVE

YKL-40 is a secretory glycoprotein of chondrocytes, synovial cells, macrophages, and neutrophils. The aims were to determine serum YKL-40 in patients with early rheumatoid arthritis (RA) and seek associations with early joint erosions.

METHODS

YKL-40 was measured by ELISA in serum samples collected every three month for 36 months from patients with early RA. The patients were treated with DMARDs and some were allocated to additional prednisolone.

RESULTS

Serum YKL-40 was higher in RA patients compared with controls (98 vs. 42 microg/l, p<0.001). The mean serum YKL-40 during the study correlated with the progression in Larsen score (Pearson's test: p=0.004). Patients with a persistently high serum YKL-40 had larger progression in Larsen score compared with patients with normal serum YKL-40 (median progression: 7 vs. 0, p=0.003).

CONCLUSION

These data suggest that elevated serum YKL-40 is related to progression in joint destruction in early RA patients.

How severe must repetitive loading be to kill chondrocytes in articular cartilage?

OBJECTIVE

Little is known about the effects of severe repetitive loading on articular cartilage chondrocytes, even though epidemiological studies associate this type of loading with osteoarthritis. We hypothesize that repetitive loading can kill cartilage chondrocytes in a dose-related manner.

DESIGN

Large cartilage-on-bone specimens were cut from the patella groove of bovine knees obtained directly from a slaughterhouse. Cartilage was loaded using a flat impermeable indenter in such a manner that the loaded region was supported naturally by surrounding cartilage and subchondral bone. Specimens received 3600 cycles of compressive loading at 1 Hz, with the peak load lying in the range 1-70% of the force required to damage cartilage in a single loading cycle (35 MPa). Cell viability was assessed in thick sections of loaded and control cartilage using a paravital staining method: fluorescein diacetate stained live cells green, and propidium iodide stained dead cells red. The assay was validated on cartilage which had been subjected to repeated freeze-thaw cycles to kill the chondrocytes.

RESULTS

Paravital staining revealed 100% cell death after one freeze-thaw cycle at -196 degrees C and three cycles at -20 degrees C. Baseline chondrocyte viability was 80% in unloaded cartilage, and viability decreased when applied compressive loading exceeded 6 MPa. Above this threshold, cell viability was inversely proportional to applied stress. When gross damage to the cartilage surface first became evident, above 14 MPa, 40% of cells remained viable. Load-induced chondrocyte death was greatest in the surface zone, and extended beyond the loaded area. Electron micrographs indicated that some cells were dying by apoptosis.

CONCLUSIONS

Some chondrocytes are much more vulnerable to repetitive mechanical loading than others, suggesting that vigorous activity may lead to cell death in articular cartilage.

Regulated expression of a dominant negative protein kinase C epsilon mutant inhibits the proliferation of U-373MG human astrocytoma cells

The tight regulation of protein kinase C (PKC) activity is crucial for maintaining normal cell proliferation. Excessive PKC activity leads to uncontrolled growth and malignant transformation. It has been reported that the activity of PKC is higher in astroglial cell lines than in normal astrocytes. Previously, we demonstrated that PKC epsilon is overexpressed in astroglial cell lines and in samples from primary high-grade astroglial brain tumors. Because there are no PKC epsilon isozyme-specific inhibitors, we chose a genetic approach to confirm that PKC epsilon is a potential target for inhibiting astroglial cell proliferation. We regulated the expression of a dominant negative PKC epsilon mutant (PKC epsilon 1-401 encoding amino acid 1-401) in U-373MG human astrocytoma cells using a tetracycline-regulated expression vector and established stable clones. Induction of expression of the dominant negative PKC epsilon mutant by the addition of doxycycline, a tetracycline derivative, completely blocked proliferation of U-373MG cells in proliferation and clonogenic assays. Although the induction of the dominant negative PKC epsilon mutant did not markedly affect mitogen-induced tyrosine phosphorylation of the mitogen-activated protein (MAP) kinases, it inhibited the induction of c-Fos protein expression by substance P (SP) and fetal bovine serum (FBS). These results clearly show that the expression of dominant negative PKC epsilon leads to the inhibition of U-373MG cellular proliferation demonstrating that this isozyme may be a potential therapeutic target for astroglial brain tumors.

Cross-sectional comparison of synovial fluid biochemical markers in equine osteoarthritis and the correlation of these markers with articular cartilage damage

OBJECTIVE

To investigate the relationship between biochemical markers in the synovial fluid of osteoarthritic and contralateral equine joints and gross articular cartilage pathology.

DESIGN

Twenty-two horses underwent bilateral arthroscopy of their carpal or metacarpophalangeal joints following recent onset lameness. The degree of cartilage damage in each joint was scored and synovial fluid, from both the clinically affected and the contralateral joint, was collected. Bone specific alkaline phosphatase (BAP), 5D4 epitope of keratan sulphate (KS), total glycosaminoglycans (GAG) and hyaluronan (HA) were measured.

RESULTS

The mean age of the horses was 4.1 years and the maximum duration of lameness was three months. Joints examined were midcarpal, antebrachiocarpal and metacarpophalangeal. The median concentration (semi-interquartile range) of BAP was significantly higher in the clinically active joint than in the contralateral joint, 21.75 (6.22) vs. 12.35 (4.07) units, while the other biomarkers measured were significantly lower in the clinically active joint than in the contralateral joint, i.e. KS 8.79 (1.96) microg/ml vs. 16.39 (5.65) microg/ml, KS:GAG ratio 0.19 (0.04) vs. 0.31 (0.10) and HA 741.6 (222) microg/ml vs. 1061.75 (325) microg/ml. BAP was positively (R=0.57), and KS (R=-0.57) and KS:GAG ratio (R=-0.49) were negatively correlated to the degree of cartilage damage within the joint.

CONCLUSION

The correlation between articular cartilage damage and synovial fluid BAP and KS imparts validity to their potential use as non-invasive diagnostic aids in equine osteoarthritis (OA). The positive correlation between BAP and cartilage damage suggests that there is a link between bone turnover and cartilage damage in OA.

Efficacy of oral calcium pentosan polysulphate for the treatment of osteoarthritis of the canine stifle joint secondary to cranial cruciate ligament deficiency

The efficacy of calcium pentosan polysulphate (CaPPS) as a slow-acting drug for the treatment of osteoarthritis of the canine stifle joint, secondary to cranial cruciate ligament deficiency, was tested in a double-blind, placebo-controlled clinical trial over a period of one year. Dogs with the deficiency were treated surgically, matched for bodyweight, and randomly assigned to treatment or placebo groups. Active treatment began six weeks postoperatively and consisted of 10 mg/kg CaPPS orally, once weekly for four weeks, repeated every 12 weeks. The outcome was assessed in terms of function by the dogs' owners, by the radiographical grading of the osteoarthritis, and by the measurement of total sulphated glycosaminoglycans and the 5D4 epitope of keratan sulphate in the synovial fluids of affected joints. There were no differences either in functional outcome or in the radiographical progression of osteoarthritis between the two groups. Fifty-four weeks after surgery, the concentration of 5D4 in synovial fluid (expressed as change from baseline values) had decreased significantly in the treatment group compared with the placebo group (P=0.03).

Increased serum C reactive protein may reflect events that precede radiographic progression in osteoarthritis of the knee

OBJECTIVE

Raised serum C reactive protein (CRP) and hyaluronate (HA) concentrations predict the progression of knee osteoarthritis (OA) in the long term but the consistency of these relations with time is unknown. The purpose of this work was therefore to determine if raised CRP and HA at entry and three years before entry (-3 years) predict radiological progression of knee OA in a group of patients between entry and five years.

METHODS

Knee radiographs from 90 patients with knee OA at entry and five years follow up were assessed for progression of disease over five years. The concentrations of serum CRP and HA were measured at entry (n=90) and also in 40 serum samples available from -3 years. Odds ratios (OR) for predicting progression were calculated by logistic regression.

RESULTS

Serum CRP at entry was not predictive of progression between entry and five years (OR 1.12, 95% CI 0.81, 1.55) but serum CRP at -3 years was predictive of progression (OR 1.90, 95% CI 1.01, 3.28). Serum HA concentration at entry predicted progression between entry and five years (OR 2.32, 95% CI 1.16, 4.66).

CONCLUSION

These results are consistent with previous reports relating to HA, and suggest that raised serum CRP reflects events that precede a period of later radiographic progression in knee OA. However, because of the large overlap between groups, the serum CRP or HA concentration are not good predictors of individual patient progression and have a poor sensitivity and specificity.

Changes in concentrations of biochemical markers of osteoarthritis following surgical repair of ruptured cranial cruciate ligaments in dogs

OBJECTIVE

To investigate longitudinal changes in concentrations of the 1/20/5D4 epitope (5D4) of keratan sulfate and total sulfated glycosaminoglycans (S-GAG) in synovial fluid and serum of dogs with cranial cruciate ligament (CCL) rupture that was repaired via intra-articular surgery.

ANIMALS

58 dogs with a ruptured CCL and osteoarthritis of the affected (index) joint.

PROCEDURE

Prior to surgical repair of the ruptured CCL, 5D4 concentration was measured in serum and synovial fluid samples by use of an inhibition ELISA, and total S-GAG concentration was measured in synovial fluid samples by use of a direct dye-binding assay. Ruptured CCL were repaired surgically, using an intra-articular fascial graft. Dogs were reexamined 1.5, 7, and 13 months after surgery, and 5D4 and S-GAG concentrations in synovial fluid and serum were measured again.

RESULTS

Serum 5D4 concentrations did not change significantly during the study. Concentrations of 5D4 in synovial fluid (expressed as a ratio of S-GAG concentration) did change significantly with time. In the index joint, the 5D4:S-GAG decreased from 0.19 at the beginning of the study to 0.09 1.5 months after surgery, but 7 months after surgery, the ratio increased again to 0.20.

CONCLUSIONS AND CLINICAL RELEVANCE

Results support the hypothesis that serum concentration of 5D4 is not a useful marker of osteoarthritis in dogs. Surgical intervention transiently reduced the concentration of 5D4 in synovial fluid but had no effect on S-GAG concentration.

Overexpression of protein kinase C epsilon in astroglial brain tumor derived cell lines and primary tumor samples

Prognosis for astroglial brain tumors that are not amenable to surgical resection remains poor. Consequently, a need to identify new cellular targets and chemotherapeutics for the treatment of astroglial tumors remains. Important reports indicate that human astroglial cell lines express higher protein kinase C (PKC) activity in comparison to normal astrocytes. PKC designates a family of kinases that regulate many cellular functions including cell growth and differentiation. The tight regulation of PKC activity is crucial for maintaining normal cellular proliferation since excessive activity leads to uncontrolled growth and cellular transformation. PKCepsilon, one of the 11 known PKC isozymes, has been shown to function as an oncogene in rodent fibroblasts by enhancing c-Raf-1 kinase activity leading to the stimulation of mitogen-activated protein (MAP) kinase pathway. We recently demonstrated that the ability of substance P (SP) neuropeptide to activate MAP kinase pathway in U-373MG astrocytoma cells correlates with its ability to selectively translocate PKCepsilon from cytosolic to membrane fraction, and that PKC inhibitors (e.g. CGP 41251) inhibit the activation of this pathway by SP or the PKC activator 12-O-tetradecanoyl phorbol 13-acetate (TPA). In this study, we demonstrated that PKCepsilon is overexpressed in many astroglial cell lines (n=27 lines), thus providing new evidence as to the possible involvement of this isozyme in the pathology of astroglial tumors. Consistently, we demonstrated that PKCepsilon is overexpressed in primary pediatric anaplastic astrocytoma (grade III) tumor samples as well as in cell lines derived from them, and that glioblastoma multiforme (grade IV) and gliosarcoma tumor samples, but not pilocytic astrocytomas (grade I), also express high levels of PKCepsilon. Therefore, the reported increase in PKC activity in brain tumor derived cell lines may be, in part, attributed to the overexpression of PKCepsilon and possibly other PKC isozymes. Consequently, we propose that the use of PKCepsilon selective inhibitors may be beneficial in the treatment of astroglial brain tumors.

A high throughput system for the evaluation of protein kinase C inhibitors based on Elk1 transcriptional activation in human astrocytoma cells

Protein kinase C (PKC) designates a family of kinases that regulate many essential functions including cell growth and differentiation. The tight regulation of PKC activity is crucial for maintaining normal cellular proliferation and excessive activity leads to abnormal or uncontrolled cell growth. Recent reports indicate that malignant glioma cell lines express 100 to 1000-fold higher PKC activity when compared to non-neoplastic astrocytes. This high activity correlates well with the proliferation of tumor cells in vitro. We recently reported on the anti-proliferative properties of selective PKC inhibitors on the growth of U-373MG human astrocytoma cell line, and their ability to block mitogen-activated protein (MAP) kinase pathway activated by substance P (SP) neuropeptide receptor signaling via a PKC-dependent mechanism. Therefore, inhibiting PKC activity by selective PKC inhibitors may present a promising approach for improving astroglial brain tumor therapy. For this purpose, we constructed a high throughput model cell system to evaluate the efficacy of PKC inhibitors. This system is based on the measurement of light production in U-373MG cells stably transfected with the luciferase reporter gene whose expression depends on the transcriptional activation of GAL4-Elk1 fusion protein by enzyme components of the MAP kinase pathway and the upstream activation of PKC (PKC activation-->MAP kinases-->GAL4-Elk1 phosphorylation-->luciferase expression-->luciferase activity). In brief, we have demonstrated that the PKC activator 12-O-tetradecanoyl phorbol 13-acetate (TPA)-induced luciferase activity in this cell system is mediated via the MAP kinase pathway and can be blocked in the presence of MEK1 selective inhibitors (PD 098059 or U0126). We also demonstrated that TPA-induced luciferase activity in U-373MG stable clones can be blocked by PKC inhibitors (CGP 41251, Go 6976, and GF 109203X) in a concentration dependent manner. In contrast, epidermal growth factor (EGF)-induced luciferase activity, which is independent of PKC activation (Ras-->Raf-1-->MEK1-->MAP kinases-->GAL4-Elk1 phosphorylation-->luciferase expression-->luciferase activity) can only be blocked using a selective EGF receptor inhibitor (AG 1478). In conclusion, we have constructed a model cell system for the high throughput screening and identification of PKC inhibitors potentially active against astrocytoma cells in culture.

Stable expression of activated Ki-Ras does not constitutively activate the mitogen-activated protein kinase pathway but attenuates epidermal growth factor receptor activation in human astrocytoma cells

Mutation in the ras oncogene is one of the most commonly reported genetic aberrations in human cancer. Activated ras mutants are thought to play a major role in promoting the growth and malignancy of tumor cells. Ras protein plays a central role in transmitting mitogenic signals from cell surface-to-nucleus by activating signaling pathways in response to receptor activation. Ras protein by recruiting c-Raf-1 kinase to the plasma membrane activates the mitogen-activated protein (MAP) kinase pathway. Expression of activated ras mutants in rodent fibroblast has been reported to constitutively activate the MAP kinase pathway, suggesting that constitutive activation of this pathway contributes to Ras influence on proliferation and transformation. In this study, we investigated whether stable expression of an activated Ki-Ras oncogenic mutant (G12V) in human astrocytoma cells leads to constitutive activation of the MAP kinase pathway and how this may influence cellular proliferation and signaling by epidermal growth factor (EGF) receptor. We discovered that Ki-Ras stable expression does not lead to constitutive activation of the MAP kinase pathway, rather expression of Ki-Ras plays a role in attenuating the activation of this pathway in response to EGF stimulation. Furthermore, we provide evidence that stable Ki-Ras expression attenuates the ability of EGF receptor to activate the MAP kinase pathway by interfering with the receptor ability to autophosphorylate at tyrosine residues and not by down regulating receptor expression.

Relations between biochemical markers of osteoarthritis and other disease parameters in a population of dogs with naturally acquired osteoarthritis of the genual joint

OBJECTIVE

To investigate the hypothesis that concentrations of the keratan sulfate epitope, 1/20/5D4 (5D4) and total sulfated glycosaminoglycans (S-GAG) in synovial fluids, and of 5D4 in serum of dogs with naturally acquired osteoarthritis of the genual joint (stifle), secondary to cranial cruciate ligament deficiency, are associated with other disease parameters of osteoarthritis.

ANIMALS

58 dogs with stifle osteoarthritis secondary to naturally acquired cranial cruciate ligament (CCL) deficiency.

PROCEDURE

All dogs were examined clinically, radiographically and, in some instances, scintigraphically. Serum and synovial fluid from both stifles were assayed for 5D4 concentration, using an inhibition ELISA, and for S-GAG, using a direct dye-binding assay.

RESULTS

Serum 5D4 concentration was not significantly associated with other disease features. Total S-GAG values were high, and 5D4 values were low, in synovial fluid from clinically active, compared with contralateral joints. The S-GAG concentration in synovial fluid from clinically active joints was negatively correlated with radiographic severity score (rs = -0.389, P = 0.004, Spearman's rank correlation). Other associations between marker concentrations and disease parameters could not be detected.

CONCLUSIONS

Serum 5D4 concentration is not a useful marker of stifle osteoarthritis in dogs; however, synovial fluid S-GAG and 5D4 values may hold more promise as disease measures.

A novel approach for examining the anti-proliferative effect of protein kinase C inhibitors against human astrocytoma cells

Prognosis for astroglial brain tumors that are not amenable to surgical resection remains poor and even successful treatment with current chemoradiotherapy is associated with debilitating sequelae. Consequently, a need to identify novel therapeutics for the treatment of brain tumors remains. Regulation of protein kinase C (PKC) whose activity regulates many cellular functions is crucial for maintaining normal cellular proliferation. Recent reports indicate that malignant glioma cell lines express 100 to 1000-fold higher PKC activity when compared to non-neoplastic astrocytes. In this study we used a novel approach for the evaluation of known PKC inhibitors (CGP 41251, Go 6976, and tamoxifen) as chemotherapeutic agents for the inhibition of growth of an astroglial derived cell line. For this purpose, we constructed a model cell system based on the measurement of light production in cells transfected with the luciferase reporter gene whose expression was quantitated by a highly sensitive, rapid, and easy to perform assay. We isolated U-373MG/MEK1C clone whose highly increased luciferase activity was independent of external stimuli and directly proportional to cell number, and therefore, was used as a measure of cell proliferation to quantitate the effects of several PKC inhibitors on growth of astrocytoma cells in vitro. In conclusion, we have constructed a novel cell system that can be utilized for high throughput screening and identification of potential anti-cancer drugs active against astrocytoma cells in culture.

Changes in biochemical markers of joint tissue metabolism in a randomized controlled trial of glucocorticoid in early rheumatoid arthritis

OBJECTIVE

To determine the effects of low-dose prednisolone on joint tissue metabolism in early rheumatoid arthritis (RA).

METHODS

In addition to a range of biochemical markers of cartilage, bone and synovial tissue turnover, levels of pro-matrix metalloproteinase 3 (pro-MMP-3), pro-MMP-1, and cytidine deaminase (CD) were measured in serum from 79 of 128 patients with early RA who took part in the Arthritis and Rheumatism Council Low-Dose Glucocorticoid Study. Serum concentrations of joint tissue metabolites on treatment and off treatment were compared using Student's t-test.

RESULTS

Levels of the keratan sulfate epitope, 5D4, and glycosaminoglycan (GAG) were similar on and off treatment. However, the levels of synovium-derived markers, hyaluronate (HA) and N-propeptide of type III procollagen (PIIINP), were reduced by 23.9% (P < 0.01) and 25.2% (P < 0.001), respectively, during treatment with prednisolone. Serum osteocalcin (OC) was reduced by 25.8% (P < 0.001), while the levels of CD and pro-MMP-3 increased by 31.2% (P < 0.01) and 53.7% (P < 0.001) during prednisolone treatment compared with the off-treatment period.

CONCLUSION

Low-dose prednisolone had no significant effect on markers of cartilage turnover (GAG, 5D4) in early RA, suggesting that early erosions do not involve cartilage surfaces. The reduction in the markers of bone turnover (OC) and synovial tissue turnover (HA and PIIINP) support the general view that prednisolone reduces synovitis and suppresses bone turnover.

Mitogenic signaling by substance P and bombesin-like neuropeptide receptors in astrocytic/glial brain tumor-derived cell lines

Neuropeptides such as substance P (SP) and bombesin regulate many biological processes through binding to and activating their respective cell surface receptors. Recently, we reported that many astrocytic/glial-derived brain tumor cell lines express functional SP and bombesin receptors (43% and 85%, respectively). Activation of these neuropeptide receptors stimulates several signaling pathways that regulate transcription and translation leading to the induction of mitogenesis in several cell types including astrocytic brain tumor-derived cell lines. We have also shown that a number of signaling pathways are induced by SP and/or bombesin receptors in astrocytic/glial-derived brain tumor cell lines and demonstrated that inhibiting these path-ways by selective compounds such as PD 098059, tamoxifen, CGP 41251, and rapamycin blocks cell growth. In summary, mitogenic signaling by neuropeptides may play a role in brain tumor growth and/or tumor progression, and selective compounds capable of blocking mitogenic signaling have potential to be useful in the treatment of brain tumors.

CGP 41251 and tamoxifen selectively inhibit mitogen-activated protein kinase activation and c-Fos phosphoprotein induction by substance P in human astrocytoma cells

The substance P (SP) receptor (NK-1 subtype) is widely expressed in primary human astrocytomas and glioblastomas and many brain tumor-derived cell lines. SP receptor activation stimulates the mitogen-activated protein (MAP) kinase pathway and the expression of immediate-early genes (e.g., c-Fos and c-Myc), resulting in an increase in DNA synthesis in human astrocytoma U-373 MG cells. In this study, we investigated the role of protein kinase C (PKC) in SP receptor activation of the MAP kinase pathway. SP peptide, epidermal growth factor, and the PKC activator 12-O-tetradecanoylphorbol-13-acetate (TPA) induced the tyrosine phosphorylation of the Erk1 and Erk2 MAP kinases in a concentration-dependent manner in U-373 MG cells. Pretreatment of the cells with PKC inhibitors, CGP 41251 or tamoxifen, inhibited tyrosine phosphorylation of Erk1 and Erk2 MAP kinases induced by low concentrations of SP or TPA and significantly attenuated phosphorylation at high concentrations of SP or TPA. The inhibitory effect exhibited by tamoxifen on SP-induced MAP kinase activation is similar to that exhibited by the selective PKC inhibitor CGP 41251, suggesting that the PKC enzyme is the in situ target for both inhibitors. Furthermore, SP-induced c-Fos phosphoprotein expression is inhibited by CGP 41251 or tamoxifen with similar efficacy. Importantly, neither CGP 41251 nor tamoxifen has any detectable effect on the MAP kinase activation by epidermal growth factor, consistent with the ability of this growth factor to activate the MAP kinase pathway by a PKC-independent mechanism. Prolonged treatment with TPA resulted in down-regulation of PKC and selective inhibition of TPA- and SP-induced Erk1 and Erk2 tyrosine phosphorylation in U-373 MG cells. Consistent with the in situ results, CGP 41251 and tamoxifen significantly inhibited endogenous PKC enzymatic activity from U-373 MG cells in vitro. In contrast to CGP 41251 and tamoxifen, Gö 6976, a highly selective inhibitor for PKC alpha and PKC beta 1 isozymes, did not inhibit SP- or TPA-induced tyrosine phosphorylation of Erk1 and Erk2 MAP kinases; rather, it inhibited a signaling pathway leading to the phosphorylation of cAMP-responsive element binding protein in U-373 MG cells. To investigate whether selective PKC isozyme(s) are involved in the activation of the MAP kinase pathway by SP, we determined the expression of PKC isozymes in U-373 MG cells. We found that U-373 MG cells express nine different PKC isozymes (alpha, beta I, beta II, epsilon, delta, eta, zeta, iota, and mu) and that stimulation with SP results in significant and selective translocation of PKC epsilon isozyme from cytosolic to membrane fraction. This establishes a correlation between the ability of SP to activate the MAP kinase pathway and its ability to translocate PKC epsilon. In conclusion, the results presented in this study demonstrate that SP receptor activation of PKC, possibly PKC epsilon, leads to the activation of the MAP kinase pathway, and that this pathway can be inhibited by known PKC inhibitors.

Relations between synovial fluid and serum concentrations of osteocalcin and other markers of joint tissue turnover in the knee joint compared with peripheral blood

OBJECTIVE

To determine if osteocalcin (OC) is locally produced in the joint and to study the relation between markers of bone, cartilage, and synovial tissue turnover.

METHODS

The concentrations of OC, keratan sulphate epitope (5D4), and hyaluronate (HA) were measured in paired serum and synovial fluid in 10 healthy volunteers and 15 patients with osteoarthritis (OA) and 16 with rheumatoid arthritis (RA). OC was measured with a commercial immunoradiometric assay and concentrations of 5D4 and HA were measured using enzyme linked immunosorbent inhibition assays.

RESULTS

Synovial fluid OC was found to be significantly lower than serum (p < 0.001) in all patients and controls. Synovial fluid OC concentrations were directly correlated with serum concentrations (r = 0.63, p < 0.001) and with age (r = 0.48, p < 0.01). There were also some relations between OC, HA, and 5D4 in patients with OA and RA. The OC concentrations were directly correlated with HA (r = 0.68, p < 0.01) in OA serum and there was a similar correlation in RA synovial fluid (r = 0.69, p < 0.01). A weak negative correlation was found between OC and 5D4 in OA serum (r = -0.55, p = 0.035) while a weak positive correlation was found in RA serum (r = 0.53, p = 0.034).

CONCLUSIONS

These results show that more OC is present in the circulation than in knee joint fluids suggesting that synovial fluid OC may be derived from the blood.

Functional expression of bombesin receptor in most adult and pediatric human glioblastoma cell lines; role in mitogenesis and in stimulating the mitogen-activated protein kinase pathway

Functional bombesin receptors were identified in most human glioblastoma cell lines examined (approximately 85% of lines). Bombesin stimulated the release of intracellular Ca2+ in human adult (U-373MG, D-247MG, U-118MG, U-251MG, D-245MG, U-105MG, D-54MG, A-172MG, and D-270MG lines) and pediatric (SJ-S6 and SJ-G2 lines) glioblastoma cell lines. Stimulation of the glioblastoma cell line U-373MG with bombesin or gastrin-releasing peptide (GRP) induced mitogenesis, measured by [3H]thymidine incorporation into DNA, and stimulated the tyrosine phosphorylation of the mitogen-activated protein (MAP) kinases (Erk1 and Erk2). The stimulation of the MAP kinase phosphorylation in U-373MG cells was time- and peptide concentration-dependent. Both bombesin and GRP showed similar potencies in stimulation of intracellular Ca2+ release and activation of the MAP kinase pathway in U-373MG cells, whereas neuromedin B (NMB) peptide was less potent. Bombesin and GRP induced the release of cytosolic Ca2+ in a concentration-dependent manner. Because bombesin and GRP were more potent than NMB peptide in increasing the cytosolic Ca2+ levels in U-373MG cells, we concluded that the BB2 subtype (also known as GRP-preferring receptor subtype) of the bombesin receptor is expressed in this cell line. The bombesin receptor antagonist ([Leu13-psi(CH2NH)Leu14]bombesin) blocked bombesin induced Ca2+ release and attenuated MAP kinase activation in U-373MG cells demonstrating that bombesin is acting through a receptor-dependent mechanism. This study indicates that functional bombesin receptors are widely expressed in human glioblastoma cell lines.

Bromocriptine transcriptionally activates the multidrug resistance gene (pgp2/mdr1b) by a novel pathway

The P-glycoprotein (Pgp) reversing agent, reserpine, induces MDR1 mRNA and PGP protein in human colon carcinoma cells (Schuetz, E. G., Beck, W. T., and Schuetz, J. D. (1996) Mol. Pharmacol. 49, 311-318) and in H35 rat hepatoma cells. Reserpine's interference with cellular dopamine utilization suggested that dopamine and dopaminergics might be important physiological regulators of PGP expression. Initial studies demonstrated that the H35 cells express the D2 dopamine receptor. Pgp protein and pgp2/mdr1b mRNA was increased (maximum of 10- and 8-fold, respectively) by the potent D2 dopamine receptor agonists bromocriptine, R(-)-propylnorapomorphine hydrochloride, and quinpirole, and Pgp protein induction was blocked by D2 receptor antagonists spiperone and clozapine. D2 receptor agonist induction of pgp2/mdr1b mRNA was paralleled by transcriptional activation of the pgp2/mdr1b promoter but blocked by pretreatment with the D2 dopamine receptor antagonists, spiperone, eticlopride, and clozapine. Co-transfection of a D2 dopamine receptor expression vector enhanced bromocriptine's transcriptional activation of the pgp2/mdr1b promoter. The G-protein, Galphai2, is required for bromocriptine transcriptional activation because the G-protein inhibitor, pertussis toxin, suppressed bromocriptine's activation of pgp2/mdr1b transcription and co-transfection of a dominant negative Galphai2 abrogated bromocriptine activation of pgp2/mdr1b. Gi proteins can transduce signals by activation of mitogen-activated protein kinases (MAPKs), and because Raf-1 is a known activator of MDR1, we tested for Raf-1 involvement. Co-transfection of a dominant negative Raf-1 failed to block bromocriptine induction of pgp2/mdr1b, and bromocriptine treatment caused no phosphorylation of the MAP kinase kinase substrates p42 and p44, demonstrating that the MAP kinase pathway was not involved. These are the first studies demonstrating transcriptional activation of an MDR gene by dopamine receptor agonists and that this activation occurs by a signal transduction pathway requiring the D2 dopamine receptor coupled to a functional G-protein.

Substance P-induced mitogenesis in human astrocytoma cells correlates with activation of the mitogen-activated protein kinase signaling pathway

The neuropeptide substance P (SP) regulates many biological processes through binding to and activating the SP receptor (NK-1 subtype). Activation of the SP receptor induces mitogenesis in several cell types. In this study, we characterized the mitogenic response induced by SP peptide in the U-373MG astrocytoma cell line and showed that activation of the SP receptor induces [3H]thymidine incorporation into DNA. We also found that SP potently induces c-myc mRNA and protein in the U-373MG cells. Tyrphostin A25, which blocks activity of tyrosine kinases, significantly inhibited SP-induced mitogenesis, suggesting that the mitogenic response induced by SP peptide involves phosphorylation by tyrosine kinases. Furthermore, stimulation of the SP receptor activates tyrosine phosphorylation and enzymatic activity of extracellular signal-regulated kinases (Erk1 and Erk2), also called the mitogen-activated protein kinases (MAPKs). This result suggests that MAPKs participate in the SP peptide-induced signaling pathway. The addition of CP 96,345 ([(2S,3S)-cis-2-(diphenylmethyl)-N-[(2-methoxyphenyl)-methyl]-1 -azabicyclo[2.2.2]octan-3-amine]; an NK-1 receptor antagonist) or PD 098059 (MEK1 inhibitor) inhibited both DNA synthesis and activation of the MAPK pathway, substantiating that SP stimulates mitogenesis by activating the MAPK pathway through receptors of the NK-1 subtype. Our results demonstrate that SP peptide is a strong mitogen in the U-373MG astrocytoma cell line and establish a clear correlation between SP-induced mitogenesis and activation of MAPK signaling pathway.

Variation of an epitope of keratan sulphate and total glycosaminoglycans in normal equine joints

An epitope of keratan sulphate (KS) and total glycosaminoglycans (GAG) were measured in synovial fluid samples from joints of 53 horses immediately following humane destruction. Internal examination of the joints post mortem ensured that there was no gross evidence of osteoarthritis or other joint disease. Joints sampled were distal interphalangeal (DIP), proximal interphalangeal (PIP), metacarpophalangeal (MCP), metatarsophalangeal (MTP), tarsometatarsal (TMT), tarsocrural (TC), femoropatellar (FP) and antebrachiocarpal (ABC) joints. The age of each horse was assessed by examination of the teeth. Samples were analysed for the KS epitope using a monoclonal antibody 5D4 and an inhibition ELISA and for total GAG level by a direct dye binding technique. There was no significant correlation between KS or GAG concentration and age. However, there were significant differences in the concentrations of KS and GAG in different joints. The median level (+semi interquartile range) of KS:GAG ratio in the MCP was significantly lower than the PIP (0.25 [0.05] vs. 0.35 [0.08]; P < 0.007) and also the DIP joints (0.25 [0.05] vs. 0.47 [0.09] P < 0.001). This study provides information which is both valuable in the investigation of normal joint metabolism and essential in the interpretation of synovial fluid KS and GAG values in their potential role as aids in the evaluation of joint disease.