Molecular characterization and partial cDNA cloning of facilitative glucose transporters expressed in human articular chondrocytes; stimulation of 2-deoxyglucose uptake by IGF-I and elevated MMP-2 secretion by glucose deprivation

OBJECTIVE

Recent evidence suggests that human chondrocytes express several facilitative glucose transporter (GLUT) isoforms and also that 2-deoxyglucose transport is accelerated by cytokine stimulation. The aim of the present investigation was to determine if human articular chondrocytes express any of the recently identified members of the GLUT/SLC2A gene family and to examine the effects of endocrine factors, such as insulin and IGF-I on the capacity of human chondrocytes for transporting 2-deoxyglucose.

DESIGN/METHODS

PCR, cloning and immunohistochemistry were employed to study the expression of GLUT/SLC2A transporters in normal human articular cartilage. The uptake of 2-deoxyglucose was examined in monolayer cultured immortalized human chondrocytes following stimulation with TNF-alpha, insulin and IGF-I. Levels of MMP-2 were assessed by gelatin zymography following glucose deprivation of alginate cultures.

RESULTS

Using PCR we detected transcripts for eight glucose transporter isoforms (GLUTs 1, 3, 6, 8, 9, 10, 11 and 12) and for a fructose transporter (GLUT5) in human articular cartilage. Expression of GLUT1, GLUT3 and GLUT9 proteins in normal human articular cartilage was confirmed by immunohistochemistry. The uptake of 2-deoxyglucose was dependent on time and temperature, inhibited by cytochalasin B and phloretin, and significantly accelerated in chondrocyte cultures stimulated with IGF-I. However, 2-deoxyglucose uptake was unaffected by short and long-term insulin treatment, which ruled out a functional role for insulin-sensitive GLUT4-mediated glucose transport. Furthermore, secretion of MMP-2 was increased in alginate cultures deprived of glucose.

CONCLUSIONS

The data supports a critical role for glucose transport and metabolism in the synthesis and degradation of cartilage.

Offering routine antenatal testing for HIV and hepatitis B in the rural setting of Cornwall

Before Department of Health directives to offer HIV and hepatitis B (HBV) testing to all pregnant women, there was little such screening in Cornwall. Through a multiagency collaborative approach a new antenatal screening programme for HIV/HBV has been introduced with high uptake in the first year (HIV 92% and HBV 93%). We also report the findings of a questionnaire survey of community midwives who alone offer antenatal HIV/HBV testing in Cornwall.

Expression and isolation of antimicrobial small molecules from soil DNA libraries

Natural products have been a critically important source of clinically relevant small molecule therapeutics. However, the discovery rate of novel structural classes of antimicrobial molecules has declined. Recently, increasing evidence has shown that the number of species cultivated from soil represents less than 1% of the total population, opening up the exciting possibility that these uncultured species may provide a large untapped pool from which novel natural products can be discovered. We have constructed and expressed in E. coli a BAC (bacterial artificial chromosome) library containing genomic fragments of DNA (5-120kb) isolated directly from soil organisms (S-DNA). Screening of the library resulted in the identification of several antimicrobial activities expressed by different recombinant clones. One clone (mg1.1) has been partially characterized and found to express several small molecules related to and including indirubin. These results show that genes involved in natural product synthesis can be cloned directly from S-DNA and expressed in a heterologous host, supporting the idea that this technology has the potential to provide novel natural products from the wealth of environmental microbial diversity and is a potentially important new tool for drug discovery.

Pseudomonas aeruginosa infection of respiratory epithelium in a cystic fibrosis xenograft model

Pulmonary infection with Pseudomonas aeruginosa in patients with cystic fibrosis (CF) causes a chronic destructive bronchitis. A xenograft model was used to study the susceptibility of the CF respiratory epithelium to P. aeruginosa strain PAK and the virulence of certain mutants. Despite an early trend toward increased susceptibility, colonization of CF xenografts (ID(95), 62 colony-forming units [cfu]) was not statistically different (P=.5) than in xenografts with normal respiratory cells (ID(95), 1.2x10(3) cfu). Infection severity in 12 CF xenografts (mean polymorphonuclear leukocyte [PMNL] density, 1.88x10(6)+/-1.75x10(6)/xenograft) was similar to that in 16 non-CF xenografts (3.19x10(6)+/-2.45x10(6) PMNL/xenograft; P=.38), despite slightly greater bacterial density in the CF xenografts (mean, 1.57+/-2.73x10(6) cfu/xenograft) versus xenografts with normal epithelium (mean, 1.03+/-1.3x10(6) cfu/xenograft). P. aeruginosa mutants pilA and fliF, but not rpoN, colonized normal respiratory xenografts, indicating that colonization and infection in this model depend on an uncharacterized RpoN-controlled gene. This model appears to be suitable for genetic study of P. aeruginosa virulence but not of the CF respiratory tract's unique susceptibility.

Patterns of memory performance in children with controlled epilepsy on the CVLT-C

Decreased memory skills have been reported in children with epilepsy. However, standardized instruments to evaluate learning and memory in children have been unavailable until recently. The present study was designed to assess memory patterns in children with epilepsy based on the California Verbal Learning Test-Children's Version (CVLT-C). The test was administered to 44 children with complex partial seizures and 21 children with generalized seizures between 8 and 13 years of age. Children in the study had been treated for epilepsy for at least 6 months, had well-controlled seizures on monotherapy, and had no evidence of anticonvulsant toxicity. Children with head injuries, learning disabilities, or hyperactivity were excluded. Test results did not reflect differences in memory performance based on seizure type. Scores for the entire sample indicated intact new learning, decreased intrusions and perseverative responses, and better short-term than long-term delayed recall. Recognition skills were stronger than long-term delayed recall skills and suggested that memory performance may be improved for these children when a multiple-choice format is available in academic settings.

Extra-anatomic redo of MIDCAB and OPCAB: an early experience

BACKGROUND

Eighteen patients with unstable angina underwent repeat myocardial revascularization without cardiopulmonary bypass using saphenous vein grafts from either the left (13) or right (2) axillary arteries or the descending thoracic aorta (3). Patients' ages ranged from 53 to 85 years. Left ventricular ejection fractions ranged from 15% to 60%.

METHODS

In 14 patients, the heart was exposed through an anterior thoracotomy, a minimally invasive direct coronary artery bypass (MIDCAB) technique. In 3 patients a left posterolateral thoractomy (lateral MIDCAB) was performed. One patient underwent repeat sternotomy (off-pump coronary artery bypass: OPCAB). In MIDCAB and lateral MIDCAB patients, the "target" vessel was a coronary artery in 8 patients and a previously placed vein graft in the remaining 9 patients. One patient underwent repeat sternotomy, and 3 coronary arteries were bypassed with a complex vein graft attached to the left axillary artery. Two patients died of mesenteric ischemia on the 2nd and 7th postoperative day. The remainder of patients were discharged from the hospital free of angina. Early graft patency was demonstrated by noninvasive vascular laboratory testing and/or angiography in the 13 survivors in whom the axillary artery had been the site of the proximal anastomosis.

RESULTS

Follow-up ranged from 1 to 25 months. No other patients have died, and none have undergone additional surgical or catheter-based procedures. Three patients have developed recurrent angina, and in 4 patients the extra-anatomic bypass grafts have apparently become occluded.

CONCLUSION

Extra-anatomic, off-pump bypass from the axillary artery or descending thoracic aorta to one or more coronary arteries can be performed safely in seriously ill patients requiring a repeat bypass procedure. The early results, regarding relief of angina, are encouraging.

Localization of metabotropic glutamate receptor type 2 in the human brain

Metabotropic glutamate receptors are a heterogeneous family of G-protein-coupled receptors that are linked to multiple second messenger systems to regulate neuronal excitability and synaptic transmission. To elucidate the physiological role of these receptors in human central nervous system function and dysfunction at the receptor protein level requires the use of selective antibodies to determine the phenotype of cells expressing particular receptor subtypes. To this end the present study has examined the regional and cellular localization of the metabotropic glutamate type 2 receptor protein in selected human brain regions. After epitope prediction, antibodies have been generated against a short synthetic peptide corresponding to amino acid residues located in the putative intracellular carboxy-terminus and subsequently applied to an immunohistochemical investigation. Antibodies specifically detected the type 2 receptor in transfected mammalian cells and also recognized a major band of 98,000 mol. wt in western blots of human brain tissue membranes. At the light microscope level immunohistochemical studies have demonstrated that type 2-like immunoreactivity was widely distributed in the human brain, being characterized by the presence of a strong immunoreaction in multiple cortical regions, and in structures comprising the basal ganglia, to include the caudate nucleus, putamen, globus pallidus, substantia nigra and subthalamic nucleus. In the hippocampal formation, immunoreactivity was predominant in selective cell layers of both the dentate gyrus and cornu ammonis, the subicular complex and entorhinal cortex. In the thalamus, multiple subnuclei showed reaction product. In the cerebellar cortex, immunoreactivity was expressed in a number of cell layers and cell types. Furthermore, using double immunofluorescence we confirmed that the type 2 receptor is a product of normal resting astrocytes in the cerebral cortex in particular. This antibody provides a new immunological tool with the potential to evaluate the distribution of human metabotropic glutamate receptor 2 protein in other brain regions and in human central nervous system diseases.

Normal tissue dosimetric comparison between HDR prostate implant boost and conformal external beam radiotherapy boost: potential for dose escalation

PURPOSE

To compare the dose and volume of bladder and rectum treated using high-dose-rate (HDR) prostate implant boost versus conformal external beam radiotherapy boost, and to use the dose-volume information to perform a critical volume tolerance (CVT) analysis and then estimate the potential for further dose escalation using HDR brachytherapy boost.

METHODS AND MATERIALS

Using CT scan data collected before and after patients underwent HDR prostate implant, a 7-field conformal prostate-only external beam treatment plan and HDR brachytherapy treatment plan were constructed for each patient. Doses to the normal structures were calculated. Dose-volume histograms (DVH) were plotted for comparison of the two techniques. Wilcoxon signed rank test was performed at four dose levels to compare the dose to normal structures between the two treatment techniques. The acute and late effects of HDR brachytherapy were calculated based on the linear-quadratic (LQ) model. CVT analyses were performed to calculate the potential dose gain (PDG) using HDR brachytherapy boost.

RESULTS

The volume of bladder and rectum receiving high dose was significantly less from implant boost. On the average, 0.19 cc of the bladder received 100% of the brachytherapy prescription dose, compared with 5.1 cc of the bladder receiving 100% of the prescription dose in the 7-field conformal external beam radiotherapy boost. Similarly, 0.25 cc of the rectum received 100% of the dose with the implant boost, as compared to 2.9 cc in the conformal external beam treatment. The implant also delivered higher doses inside the prostate volume. On average, 47% of the prostate received > or =150% of the prescription dose. The CVT analysis revealed a range of PDG using the HDR brachytherapy boost which depended on the following variables: critical volume (CV), critical volume tolerance dose (CVTD), number of HDR fractions (N), and the dose of external beam radiotherapy (XRT) delivered with brachytherapy boost. The PDG varied from -3.45% to 10.53% for tumor with an alpha-beta ratio of 10 and 7.14% to 64.6% for tumor with an alpha-beta ratio of 1.5 based on the parameters used for calculation in this study.

CONCLUSIONS

HDR brachytherapy can provide better sparing of rectum and bladder while delivering a higher dose to the prostate. Even with the increased late effects of high dose per fraction, there is still a potential for dose escalation beyond external radiotherapy limits using HDR brachytherapy.

An improved method for the determination of fluticasone propionate in human plasma

Therapeutic monitoring of the potent, highly lipophilic glucocorticoid, fluticasone propionate (FP), was initially performed by a radioimmunoassay method. However an improved method with a lower limit of quantitation (LLOQ) of at least 25 pg per ml (pg/ml(-1)) was needed to measure the low levels of FP present in human plasma following inhalation administration of doses in the range 50-250 microg twice daily. A sensitive and specific liquid chromatographic, tandem mass spectrometric method (LC-MS/MS) with automated solid phase extraction (SPE) was developed and validated. Fluticasone propionate was extracted from plasma using Bond Elut C18 cartridges and analysed using reverse-phase chromatography with atmospheric pressure chemical ionisation followed by selective reaction monitoring. The method used a 13C-labelled internal standard and was validated over a concentration range of 25-500 pg/ml(-1). The method was shown to be specific, sensitive and reliable in the analysis of clinical samples. The main advantages of this method over the radioimmunoassay method previously used were improved sensitivity, specificity, ease of sample preparation and shortened analysis time.

A phase 3 randomized study of radiotherapy plus procarbazine, CCNU, and vincristine (PCV) with or without BUdR for the treatment of anaplastic astrocytoma: a preliminary report of RTOG 9404

PURPOSE

This study was an open label, randomized Phase 3 trial in newly diagnosed patients with anaplastic glioma comparing radiotherapy plus adjuvant procarbazine, CCNU, and vincristine (PCV) chemotherapy with or without bromodeoxyuridine (BUdR) given as a 96-hour infusion each week of radiotherapy.

METHODS AND MATERIALS

Only patients 18 years or older with newly diagnosed anaplastic glioma were eligible; central pathology review was accomplished, but was not mandated prior to registration. The study had initially opened as a Northern California Oncology Group (NCOG) trial in 1991, becoming an Intergroup RTOG, SWOG, and NCCTG study in July 1994. Total accrual of 293 patients was planned as the sample size, using survival and time to tumor progression as the primary endpoints. The experiment arm (RT/BUdR plus PCV) was to be compared to the control arm (RT plus PCV) using an alpha = 0.05, one-tailed, with a power of 85% for detecting an increase in median survival from 160 to 240 weeks, assuming a 3-year follow-up after completion of enrollment.

RESULTS

As of July 1996, 281 patients had been randomized; 53 (20%) were ineligible, primarily based upon central pathology review, and another 39 cases were canceled. In total, 30% of cases were excluded from analysis. The treatment arms were well balanced despite this rate of exclusion. The RTOG Data Monitoring Committee recommended suspension of enrollment in July 1996 based upon a stochastic curtailment analysis which strongly suggested that the addition of BUdR would not be associated with increased survival. In February 1997, the study was closed prior to full enrollment. At that time, the 1-year survival estimates were 82% versus 68% for RT plus PCV and RT/BUdR plus PCV respectively (one-sided, p = 0.96). The conditional power analysis indicated that even with an additional 12 months of additional accrual and follow-up the probability of detecting the prespecified difference was less than 0.01%. The differences in the two arms seem to be due to early deaths in the BUdR arm, not related to toxicity of the treatment.

CONCLUSIONS

Despite encouraging Phase 2 results with BUdR, it is unlikely that a survival benefit will be seen. A final study analysis will not be done for at least 3 more years.

Simultaneous assay of Src SH3 and SH2 domain binding using different wavelength fluorescence polarization probes

pp60(c-src) is a prototypical nonreceptor tyrosine kinase and may play a role in diseases as diverse as cancer and osteoporosis. In Src, the SH3 domain (Src homology 3) binds proteins at specific, proline-rich sequences, while the SH2 domain (Src homology 2) binds phosphotyrosine-containing sequences. Inhibition of Src SH3 and SH2 domain function is of potential therapeutic value because of their importance in signaling pathways involved in disease states. We have developed dual-wavelength fluorescent peptide probes for both the Src SH3 and the Src SH2 domains, which allow the simultaneous measurement of compounds binding to each domain in assays based on the technique of fluorescence polarization. We demonstrate the utility of these probes in a dual-binding assay (suitable for high-throughput screening) to study the interactions of various peptides with these domains, including a sequence from the rat protein p130(CAS) which has been reported to bind simultaneously to both Src SH3 and SH2 domains. Utilizing this dual-binding assay, we confirm that sequences from p130(CAS) can simultaneously bind Src via both its SH3 and its SH2 domains. We also use the dual-binding assay as an internal control to identify substances which inhibit SH3 and SH2 binding via nonspecific mechanisms.

The proliferative capacity of neonatal skin fibroblasts is reduced after exposure to venous ulcer wound fluid: A potential mechanism for senescence in venous ulcers

PURPOSE

We have previously shown that fibroblasts cultured from venous ulcers display characteristics of senescence and have reduced growth rates. Susceptibility of young fibroblasts to the microcirculatory changes associated with venous ulcers, such as macrophage trapping and activation, could explain the prevalence of senescent fibroblasts in these wounds.

METHODS

We tested the in vitro effect of venous ulcer wound fluid (VUWF), as well as pro-inflammatory cytokines known to be present in VUWF (TNF-alpha, IL-1beta, and TGF-beta1), on neonatal foreskin fibroblasts (NFFs). NFF growth rates, cellular morphology, and senescence-associated beta-galactosidase (SA-beta-Gal) activity were determined in the presence or absence of VUWF and the above cytokines. VUWF TNF-alpha concentration and the effect of anti-TNF-alpha antibody on VUWF inhibitory activity were determined in samples obtained from four patients with venous ulcers.

RESULTS

NFF growth rates were significantly reduced by VUWF (42,727 +/- 6301 vs 3902 +/- 2191 P =. 006). TNF-alpha also significantly reduced NFF growth rates in a dose-dependent manner (P =.01). No significant growth-inhibitory activity was seen for IL-1alpha or TGF-beta. Incubation with VUWF significantly increased the percentage of SA-beta-Gal-positive fibroblasts in vitro on culture day 12 (P =.02). TNF-alpha and TGF-beta1 had similar effects. TNF-alpha was detected in all VUWF tested, with a mean of 254 +/- 19 pg/mL.

CONCLUSION

These data suggest that the venous ulcer microenvironment adversely affects young, rapidly proliferating fibroblasts such as NFFs and induces fibroblast senescence. Pro-inflammatory cytokines such as TNF-alpha and TGF-beta1 might be involved in this process. The role of other unknown inhibitory mediators, as well as pro-inflammatory cytokines, in venous ulcer development and impaired healing must be considered.

Quality of life and anxiety in a phase II cardiac rehabilitation program

PURPOSE

Cardiac rehabilitation programs increasingly attempt to improve both quantity and quality of life (QOL). Documenting QOL changes requires appropriate instruments, and interpreting QOL data requires an understanding of the factors that influence such reports.

METHODS

To address both issues, we assessed QOL among 77 patients before and after participation in a 12-wk phase II cardiac rehabilitation program. Individual psychological differences in trait anxiety and defensiveness were also assessed. The sample was 76.6% male, 70.1% married, and had a mean age of 58.8 yr.

RESULTS

The QOL scales detected changes which occurred over the 12-wk testing period. QOL reports were strongly and differentially influenced by individual differences in trait anxiety, such that patients reporting high trait anxiety displayed poorer QOL than those low in trait anxiety. More specifically, trait anxiety influenced affect reports most strongly, functional aspects moderately, and physical aspects of QOL reports the least.

CONCLUSIONS

Defensiveness was unrelated to QOL reports. The 17% of participants who voluntarily left the rehabilitation program prematurely were characterized as younger, having better self-perceived health, having a less severe cardiac history, and being high in both trait anxiety and defensiveness. Study benefits and limitations are discussed.

Ethanol-induced expression of c-Fos differentiates the FAST and SLOW selected lines of mice

The effect of ethanol on the number of Fos-like immunoreactive (Fos-li) neurons was previously studied in the C57BL/6J (B6) and DBA/2J (D2) inbred mouse strains (Hitzemann and Hitzemann, 1997). Data obtained suggested that the locomotor activation response to ethanol found in the D2 but not the B6 strain was associated with an increase in the number of Fos-li neurons (a putative measure of synaptic activity) in the central nucleus of the amygdala (CeA), but not in other brain regions, including the basal ganglia. Supporting results were obtained in B6D2 F2 intercross animals (Demarest et al., 1998) those animals exhibiting a marked locomotor activation response to ethanol also showed a significant increase in the number of Fos-li neurons in the CeA. The current study extends this line of investigation to the FAST and SLOW selected lines of mice (Shen et al., 1995). Twenty-eight SLOW and FAST mice (taken evenly from both replicate lines) were randomly assigned to receive either saline or ethanol (1.5 g/kg). One hour later, the animals were sacrificed, and the number of Fos-li neurons were determined using standard immunocytochemical techniques. Both the FAST and SLOW lines showed a marked increase (>300%) in the number of Fos-li neurons in the lateral aspect of the CeA; however, in the capsular division, only the FAST line showed an increase (>500%). In several brain regions, the basal (saline) response was markedly higher in the SLOW line; these regions included the subthalamic nucleus, the entopeduncular nucleus, the substantia nigra compacta, and the ventral tegmental area. Furthermore, it was found that ethanol decreased the number of Fos-li neurons in the ventral tegmental area of the SLOW but not FAST mice. These data suggest a substantial involvement of the basal ganglia in the segregation of the FAST and SLOW lines.

Fibroblasts cultured from distal lower extremities in patients with venous reflux display cellular characteristics of senescence

PURPOSE

Venous reflux precedes the development of venous ulcers. Our earlier work showed that the fibroblasts that are cultured from these wounds display more characteristics of senescence. We evaluated fibroblast senescence in patients with venous reflux but without ulcers to further investigate the role of venous reflux in the predisposition to venous ulcers.

METHODS

Fibroblasts that were isolated from skin biopsy specimens of the "gaiter" area (distal) and of the ipsilateral thigh of the same patient (proximal) were compared. Twelve patients with venous reflux (9 patients in clinical, etiologic, anatomic, and pathologic classification 4; 3 patients in classification 5) with an average venous filling index of 5.45 mL/s and 4 patients without venous reflux were enrolled in the study. The growth rates, the response to basic fibroblast growth factor (b-FGF), and the senescence markers (beta-galactosidase activity at a pH level of 6, unstimulated fibroblasts fibronectin protein, and messenger RNA levels) were determined for each cell population.

RESULTS

The number of senescence-associated beta-galactosidase positive cells (8.3% +/- 1.9% vs 2.2% +/- 0.8%; P =.008) and the level of cellular fibronectin protein (455.7 +/- 80 vs 210 +/- 51; P =.04) and messenger RNA (16.8 +/- 6.8 vs 13.5 +/- 5.7; P =.042) were significantly higher in the distal fibroblasts as compared with the proximal fibroblast cultures. The growth rates of the distal fibroblasts were lower when compared with the proximal fibroblasts (15,746 +/- 4287 cells/day vs 29,550 +/- 5035 cells/day; P <.002) but were not different in the presence of b-FGF (41,717 +/- 9542 cells/day vs 47,030 +/- 6133 cells/day; P =.53). In the patients without venous reflux, no site differences were noted in the growth rates or the senescence markers between the proximal and distal fibroblasts.

CONCLUSION

Distal fibroblasts that are isolated from patients with venous reflux display more senescence characteristics than do proximal fibroblasts and have significantly lower growth rates. Despite senescence, b-FGF restored the distal-fibroblasts growth rate to that of the stimulated proximal fibroblasts, which proposes a therapeutic role for b-FGF. These changes precede ulcer formation and suggest a mechanism that is focal and intrinsically related to venous reflux.

Fibroblasts cultured from venous ulcers display cellular characteristics of senescence

PURPOSE

A well-recognized characteristic of venous ulcers is impaired healing. Fibroblasts cultured from venous ulcers (wound-fb) have been shown to have reduced growth rates and are larger than normal fibroblasts (normal-fb) from the ipsilateral limb. Reduced growth capacity and morphologic changes are 2 well-known traits of cellular senescence. Other molecular changes are overexpression of matrix proteins, such as cellular fibronectin (cFN), and enhanced activity of beta-galactosidase at pH of 6.0 (senescence associated beta-Gal, or SA-beta-Gal). Senescence, an irreversible arrest of cell proliferation with maintenance of metabolic functions, may represent in vivo aging and thus may be related to impaired healing.

METHODS

Cultured normal-fb and wound-fb from 7 venous ulcer patients (average age, 51 years) were obtained by taking punch biopsies of the perimeter of the ulcer and from the ipsilateral thigh of the same patient. Growth rates, SA-beta-Gal activity, and level of cFN protein (immunoblot) and message (Northern blot) were measured.

RESULTS

In all patients, wound-fb growth rates were significantly lower than those of normal-fb (P =.006). A higher percentage of SA-beta-Gal positive cells were found in all wound-fb (average, 6.3% vs. 0.21%; P =.016). The level of cFN, was consistently higher in all wound-fb tested. Also, in 4 patients, the level of cFN messenger RNA (mRNA) was increased.

CONCLUSION

Fibroblasts cultured from venous ulcers exhibited characteristics associated with senescent cells. Accumulation of senescent cell in ulcer environment may be associated with impaired healing.

2nd-trimester maternal serum marker results are not altered by delayed analysis

OBJECTIVE

The goal of the study was to evaluate the significance of delayed laboratory analysis of maternal serum alpha-fetoprotein, beta-subunit of human chorionic gonadotropin, and unconjugated estriol for prenatal screening.

METHODS

Biochemical analysis of 30 consecutive biochemical screening specimens of maternal serum alpha-fetoprotein, beta-subunit of human chorionic gonadotropin, and unconjugated estriol was performed immediately upon arrival to the laboratory, 7 days later, and again 14 days after maternal blood was drawn. Differences among the results of the three sets of biochemical studies were evaluated by one-way analysis of variance for repeated measures.

RESULTS

No significant differences were found among the results of immediate assays as compared with those at a 7- or a 14-day delay for all three biochemical markers.

CONCLUSIONS

Our data suggest that up to a 14-day delay in the performance of the 2nd-trimester maternal serum biochemical screening assays will not alter the results significantly. The results of maternal serum screening are, thus, clinically valid even if the laboratory assays were performed several days after maternal blood was drawn.

Human metabotropic glutamate receptor 2 couples to the MAP kinase cascade in chinese hamster ovary cells

We have examined the functional coupling of the human metabotropic glutamate receptor type 2 (mGluR2) with the regulation of the mitogen activated protein kinase (MAP kinase) signal transduction cascade. We demonstrated that L-glutamate stimulation of the human mGluR2 receptor transiently expressed in chinese hamster ovary (CHO) cells leads to a rapid increase in the activity of p42/p44 MAP kinase (also known as the extracellular signal regulated kinases, ERK1 and ERK2). Activation of p42/p44 MAP kinase has been demonstrated in a peptide phosphorylation assay and through the demonstration of a shift in electrophoretic mobility of p42 MAP kinase following activation. In both assay systems L-glutamate stimulation of MAP kinase was inhibited by pertussis toxin and by the MEK (MAP/ERK activating kinase) inhibitor PD 98059. We conclude that L-glutamate stimulation of the mGluR2 receptor in CHO cells mediated regulation of p42/p44 MAP kinase following the activation of pertussis toxin-sensitive G alpha(i) G-proteins via a distinct protein kinase signalling pathway that utilizes MEK.

Immunohistochemical localisation of mGluR7 protein in the rodent and human cerebellar cortex using subtype specific antibodies

Metabotropic glutamate receptors (mGluRs) are a heterogeneous family of G protein coupled receptors that are linked to multiple second messenger systems to regulate neuronal excitability and synaptic transmission. To characterise the protein expression of the two mGluR7 receptor splice variants in human and rat cerebellar cortex, antibodies specific to mGluR7 were generated. Antibodies were raised against a glutathione-S-transferase fusion protein containing amino acid residues located in the extracellular domain common to both the human and rat mGluR7 splice variants. These antibodies specifically detected human mGluR7a in mammalian cells transfected with this receptor. In agreement with mGluR7 in situ hybridisation studies, immunohistochemistry performed at the light microscope level revealed that mGluR7 protein expression occurred most prominently in a particular population of nerve cells common to both the human and rat, located within the cerebellar cortex of gray matter contained within transverse folia. Moreover, strong mGluR7-like immunoreactivity was seen in Purkinje cell body cytoplasm of the Purkinje cell layer. In the most superficial cerebellar cortical layer, the molecular layer, immunostaining was observed in Purkinje cell associated proximal and distal dendritic trees. No detectable labelling was evident in intrinsic deep cerebellar nuclei known to contain GABAergic terminals of projecting Purkinje cell axons. These data are suggestive of a post-synaptic location of mGluR7 in this central nervous system structure. In the rodent, additional non-Purkinje cells thought to represent inhibitory interneurones were labelled at all levels in the molecular layer. mGluR7-like immunoreactivity was not associated with glial cells.