Platelet kinetics in autosomal dominant macrothrombocytopenia

A family with autosomal dominant macrothrombocytopenia is described. Despite severe thrombocytopenia, only a moderate hemorrhagic tendency was observed. Kinetic studies revealed a normal platelet survival, normal megakaryocytic numbers, and normal bone marrow responsiveness. The rate of platelet production was set low, despite moderately impaired hemostasis and thrombocytopenia; it apparently was set to maintain another platelet parameter at an optimal level. Measurements of total circulating platelet mass and platelet surface suggested that the platelet production was set to maintain the platelet surface rather than the platelet mass at a normal value.

Youth counseled for HIV testing at school- and hospital-based clinics

The prevalence of human immunodeficiency virus (HIV) in adolescents is difficult to assess as few adolescents consent to testing. This prospective study characterized urban youth requesting HIV testing at two types of health settings, inner-city school-based and hospital-based clinics. Data were obtained on 1652 inner-city youths aged 13 to 19 years who consented to individualized HIV counseling and testing from January 1993 to January 1994. Identified risks for HIV included sexual activity, sexually transmitted disease (STD) history, and substance use by self-report during a confidential structured interview. Data were analyzed using chi-squared analysis. Of the 1652 youth who were counseled, 1602 were from hospital-based clinics. A total of 827 (50%) requested HIV testing. Females accounted for the majority of youth who underwent counseling (79%) and requested HIV testing (75%). However, once counseled, males were more likely to be tested. Risk factors differed by gender; females were more likely to report STDs and marijuana use, and males more likely to report alcohol and cocaine use. These results indicate a need to identify developmentally appropriate methods to educate and counsel youth about HIV that will lead to more youth willing to be tested. School-based clinics may provide easier access than traditional health models for confidential HIV services.

[Strategies for identification of secretases implicated in Alzheimer's disease]

In Alzheimer's disease, cortical areas of affected patients are invaded by extracellular proteinous deposits called senile plaques, the main component of which is called amyloid beta-peptide or A beta. This peptide derives from the proteolytic attack of a precursor, the beta-amyloid precursor protein, by two enzymes called beta- and gamma-secretases. Alternatively, beta APP can be cleaved by an additional activity named alpha-secretase that occurs inside the A beta sequence, thereby precluding its formation, and concomitantly liberating a secreted fragment, namely APP alpha. Therefore, secretases seem to play a key role in the control of physiological and potentially pathogenic beta APP catabolites and could be envisioned as possible therapeutic targets in Alzheimer's disease. Here, we describe possible experimental approaches to identify such proteolytic activities.

Differential expression of systemic cytokine profiles in Chagas' disease is associated with endemicity of Trypanosoma cruzi infections

Chagas' disease is a serious public health problem in Paraguay, however, the immunoepidemiology of the disease has not been well documented. A preliminary cross-sectional survey was carried out in two villages of the Paraguayan Chaco region and in five villages of the Oriental region to assess the endemicity of Trypanosoma cruzi infections. Thereafter, a subset of individuals (ages ranging from 23 to 65 years) participated in a follow-up study to evaluate clinical and parasitological parameters. Physical examinations and electrocardiograms (ECG) were conducted and blood samples collected for parasite detection and serology. The most frequent ECG abnormalities which were observed among chagasic individuals were left anterior hemifascicular block and right bundle branch block. Thirty-two of these subjects, seropositive and non-parasitemic from the high endemic Chaco (n = 16) and low endemic Oriental (n = 16) regions, were randomly selected for an analysis of T. cruzi-induced expression of cytokines IL-2, IFN-gamma, IL-4 and IL-10 by RT-PCR. The individuals were grouped (n = 8) according to the presence or absence of abnormal ECG. In subjects that exhibited abnormal ECG profiles, five of eight (63%) individuals from the high endemic area showed a dominant type 2 (IL-4) response, whereas a comparable number (63%) of subjects from the low endemic area expressed a strong type 1 (IFN-gamma) response; the remainder (37%) presented a Th0-type (IFN-gamma, IL-4) response. Subjects with normal ECG showed a defined cytokine profile according to endemicity. All subjects from the high endemic region showed a Th0 response, whereas 100% of the individuals from the low endemic area demonstrated a type 1 response. In most chagasic patients regardless of ECG profile and endemicity, IL-2 expression was depressed, while IL-10 mRNA transcripts were consistently elevated. Taken together, these data indicate that chronic human chagasic disease is associated with increased systemic production of type 2 cytokines in response to T. cruzi infection and may be involved in the reciprocal down-regulation of IL-2 production.

Neurocircuitry of conditioned inhibition of analgesia: effects of amygdala, dorsal raphe, ventral medullary, and spinal cord lesions on antianalgesia in the rat

Pain inhibition (analgesia) is produced by learned danger signals and inhibited by learned safety signals (antianalgesia). Conditioned analgesia is mediated by brain-to-spinal pathways releasing spinal endogenous opiates. Spinal morphine mimics learned danger signals in producing analgesia, which is inhibited by antianalgesia. The circuitry mediating antianalgesia is unknown. These experiments demonstrate that raphe dorsalis, raphe magnus, and spinal dorsolateral funiculus lesions abolish antianalgesia. Other lesions had no effect on antianalgesia. More important, lesions that blocked development of conditioned analgesia did not block development of antianalgesia. Thus, neural circuitries mediating analgesia and antianalgesia were found to be distinct, and conditioned inhibition of analgesia was found to act by inhibiting the most distal part of the conditioned analgesia circuit, namely, the spinal cord.

Budesonide epimer R or dexamethasone selectively inhibit platelet-activating factor-induced or interleukin 1beta-induced DNA binding activity of cis-acting transcription factors and cyclooxygenase-2 gene expression in human epidermal keratinocytes

To further understand the molecular mechanism of glucocorticoid action on gene expression, DNA-binding activities of the cis-acting transcription factors activator protein 1 (AP1), AP2, Egr1 (zif268), NF-kappaB, the signal transducers and activators of transcription proteins gamma interferon activation site (GAS), Sis-inducible element, and the TATA binding protein transcription factor II D (TFIID) were examined in human epidermal keratinocytes. The cytokine interleukin 1beta (IL-1beta) and platelet-activating factor (PAF), both potent mediators of inflammation, were used as triggers for gene expression. Budesonide epimer R (BUDeR) and dexamethasone (DEX) were studied as potential antagonists. BUDeR or DEX before IL-1beta- or PAF-mediated gene induction elicited strong inhibition of AP1-, GAS-, and in particular NF-kappaB-DNA binding (P < 0.001, ANOVA). Only small effects were noted on AP2, Egr1 (zif268), and Sis-inducible element-DNA binding (P > 0.05). No significant effect was noted on the basal transcription factor TFIID recognition of TATA-containing core promoter sequences (P > 0.68). To test the hypothesis that changing cis-acting transcription factor binding activity may be involved in inflammatory-response related gene transcription, RNA message abundance for human cyclooxygenase (COX)-1 and -2 (E.C.1.14.99.1) was assessed in parallel by using reverse transcription-PCR. Although the COX-1 gene was found to be expressed at constitutively low levels, the TATA-containing COX-2 gene, which contains AP1-like, GAS, and NF-kappaB DNA-binding sites in its immediate promoter, was found to be strongly induced by IL-1beta or PAF (P < 0.001). BUDeR and DEX both suppressed COX-2 RNA message generation; however, no correlation was associated with TFIID-DNA binding. These results suggest that on stimulation by mediators of inflammation, although the basal transcription machinery remains intact, modulation of cis-activating transcription factor AP1, GAS, and NF-kappaB-DNA binding by the glucocorticoids BUDeR and DEX play important regulatory roles in the extent of specific promoter activation and hence the expression of key genes involved in the inflammatory response.

Prospective Evaluation of Referrals to a Hospice/Palliative Medicine Consultation Service

A hospice/palliative medicine consultation team was formed in July 1993 in a U.S. teaching hospital to provide patient care and education. The team consists of an attending physician, nurse, fellow, and any residents or medical students rotating on the service. More than 500 consultations are received each year. Beginning in January 1995,108 consecutive referrals to the service were assessed using a standard form completed by the nurse. The average age was 62 years. The gender of patients was 58% male and 42% female. At the time of consultation 87% were hospitalized on general medical services (including hematology/oncology), 4% were on surgical services, 3% on the neurology service, and 6% were in an intensive care unit. Cancer was the primary diagnosis in 52%, AIDS in 24%, with the rest being distributed among cardiac, renal, pulmonary, neurologic, and other diseases. The most prominent physical symptoms were 48% weakness/malaise, 44% pain, 28% dyspnea, and 23% agitation/confusion. The average length of time patients were followed was 2 days (range 1-10). We conclude that a hospice/palliative medicine consultation service sees a broad range of patients and problems and is a rich resource for teaching hospice and palliative medicine.

Tenidap decreases IL-8 and monocyte chemotactic peptide-1 (MCP-1) mRNA expression in the synovial tissue of rabbits with antigen arthritis and in cultured synovial cells

Since IL-8 and MCP-1 are chemoattractant proteins that participate in the recruitment of inflammatory cells into the arthritic joint, we examined the effects of tenidap, a new anti-inflammatory drug of the oxindole family, on IL-8 and MCP-1 expression in the joints of rabbits with acute antigen arthritis. The model was induced by injecting 5 mg/ml ovalbumin into the knees of 20 preimmunized rabbits. Animals were randomized into two groups: treated with tenidap (15 mg/kg per 12 h), or untreated. The effect of tenidap treatment was evaluated on chemokine production in synovial membranes of rabbits with arthritis and in cultured monocytic and synovial cells (SC). By immunoperoxidase staining, chemokines were localized in the synovial tissue. Chemokine messenger RNA levels in the synovial membranes and in cultured cells were analysed by reverse transcription-polymerase chain reaction (RT-PCR). At the end of the study, tenidap significantly reduced neutrophil infiltration into the joint cavity (27+/-4 x 10(6) cells/ml versus 45+/-6 x 10(6) cells/ml in untreated; P<0.05), and synovial effusion (134+/-15 microl versus 236+/-19 microl in untreated; P<0.005). Untreated rabbits showed synovial membrane up-regulation in mRNA expression of IL-8 and MCP-1 (11- and seven-fold versus healthy rabbits, respectively) that was markedly decreased by tenidap (two- and three-fold versus healthy rabbits, respectively). IL-8 and MCP-1 were localized in the synovial tissue in a perivascular pattern and areas of the interstitium and lining, mostly coinciding with cell infiltration. Tenidap also reduced the accumulation of IL-8 and MCP-1 proteins. In cultured synovial and monocytic cells, tumour necrosis factor-alpha (TNF-alpha) elicited an increase in gene expression of IL-8 (four- and nine-fold, respectively) and MCP-1 (nine- and four-fold, respectively) that was significantly reversed in both cell types by 10 microM tenidap. These results suggest that the beneficial effect of tenidap in acute antigen arthritis could be related to the down-regulation in gene expression and synthesis of IL-8 and MCP-1, two key chemokines involved in the recruitment of inflammatory cells.

Inhibition of cyclobutane pyrimidine dimer formation in epidermal p53 gene of UV-irradiated mice by alpha-tocopherol

Mutations or alterations in the p53 gene have been observed in 50-100% of ultraviolet light (UV)-induced squamous cell carcinoma in humans and animals. Most of the mutations occurred at dipyrimidine sequences, suggesting that pyrimidine dimers in the p53 gene play a role in the pathogenesis of cutaneous squamous cell carcinoma. We previously showed that topical alpha-tocopherol prevents UV-induced skin carcinogenesis in the mouse. In the present study we asked whether topical alpha-tocopherol reduces the level of UV-induced cyclobutane pyrimidine dimers in the murine epidermal p53 gene. Mice received six dorsal applications of 25 mg each of alpha-tocopherol, on alternate days, before exposure to 500 J/m2 of UV-B irradiation. Mice were killed at selected times after irradiation. The level of dimers in the epidermal p53 gene was measured using the T4 endonuclease V assay with quantitative Southern hybridization. Topical alpha-tocopherol caused a 55% reduction in the formation of cyclobutane pyrimidine dimers in the epidermal p53 gene. The rate of reduction of pyrimidine dimers between 1 and 10 hours after irradiation was similar in UV-irradiated mice, regardless of alpha-tocopherol treatment. Therefore, the lower level of cyclobutane pyrimidine dimers in UV-irradiated mice treated with alpha-tocopherol than in control UV-irradiated mice resulted from the prevention of formation of the dimers, and not from enhanced repair of these lesions. Our results indicate that alpha-tocopherol acts as an effective sunscreen in vivo, preventing the formation of premutagenic DNA lesions in a gene known to be important in skin carcinogenesis.

VE-Cadherin mediates endothelial cell capillary tube formation in fibrin and collagen gels

Various cell adhesion molecules mediate the diverse functions of the vascular endothelium, such as cell adhesion, neutrophil migration, and angiogenesis. In order to identify cell adhesion molecules important for angiogenesis, we used an in vitro model (Chalupowicz, Chowdhury, Bach, Barsigian, and Martinez, J. Cell Biol. 130, 207-215, 1995) in which human umbilical vein endothelial cell monolayers are induced to form capillary-like tubes when a second gel, composed of either fibrin or collagen, is formed overlying the apical surface. In the present investigation, we observed that a monoclonal antibody directed against the first extracellular domain of human vascular endothelial cadherin (VE-cadherin, cadherin 5) inhibited the formation of capillary tubes formed between either fibrin or collagen gels. Moreover, when added to preformed capillary tubes, this antibody disrupted the capillary network. In contrast, monoclonal antibodies directed against the extracellular domain of N-cadherin, the alphavbeta3 integrin, and PECAM-1 failed to inhibit capillary tube formation. During capillary tube formation, Western blot and RT-PCR analysis revealed no marked change in VE-cadherin expression. Immunocytochemical studies demonstrated that VE-cadherin was concentrated at intercellular junctions in multicellular capillary tubes. Thus, VE-cadherin plays a specific role in fibrin-induced or collagen-induced capillary tube formation and is localized at areas of intercellular contact where it functions to maintain the tubular architecture. Moreover, its function at tubular intercellular junctions is distinct from that at intercellular junctions present in confluent monolayers, since only the former was inhibited by monoclonal antibodies.

Synthesis and biological activity of glutamic acid derivatives

In order to develop new specific glutamate analogues at metabotropic glutamate receptors, Diels-Alder, 1-4 ionic and radical reactions were performed starting from (2S)-4-methyleneglutamic acid. Preliminary pharmacological evaluation by measuring IP accumulation using rat forebrain synaptoneurosomes has shown that (2S)-4-(2-phthalimidoethyl)glutamic acid (3a), (2S)-4-(4-phthalimidobutyl)glutamic acid (3b) and 1-[(S)-2-amino-2-carboxyethyl]-3,4-dimethylcyclohex-3-ene-1-carbox ylic acid (8) presented moderate antagonist activities.

Cytokine responses in Trypanosoma cruzi-infected children in Paraguay

Both parasite and host immune factors may contribute to the development and progression of chronic chagasic cardiomyopathy during Trypanosoma cruzi infections. The present study targeted infected children (5-14 years of age) from an endemic area of Paraguay in an analysis of T. cruzi-specific cytokine profiles. This age group is characteristically the most affected by the early phases of infection. Trypanosoma cruzi-induced cytokine gene expression (interleukin-2 [IL-2], and interferon-gamma [IFN-gamma], IL-4, and IL-10) was studied in 25 seropositive children categorized as being either acute, symptomatic, with Romana's sign (n = 2), or early, indeterminate (postacute, n = 23). Acutely infected children showed a distinct T helper cell-1 (Th1)-type (IFN-gamma) cytokine response to infection. The cytokine pattern that was observed in the seropositive, asymptomatic (early, indeterminate) group was of the Th0 type (expression of both IFN-gamma and IL-4). We hypothesize that selective induction of a Th0-type cytokine pattern is important for development of cell-mediated and humoral immune responses that suppress parasite burden, thereby prolonging the onset or limiting the severity of chronic Chagas' disease later in life.

Comparative study of in vitro and in vivo activities of bombesin pseudopeptide analogs modified on the C-terminal dipeptide fragment

Analogs of bombesin in which the peptide bond between the two last amino acid residues were replaced by a pseudopeptide bond mimicking the transition state analog were evaluated. These compounds were able to recognize the bombesin receptor on isolated rat pancreatic acini with high potency (Ki from 0.60 +/- 0.27 nM to 4.3 +/- 2.3 nM). Although they were devoid of agonist activity, they were able to antagonize bombesin-induced amylase secretion in this model, with potencies in accordance with their affinities (IC50 from 1.6 +/- 0.3 nM to 10.0 +/- 1.7 nM). When tested in vivo in the anesthetized rat, these bombesin receptor antagonists exhibited high potency in inhibiting bombesin-induced pancreatic secretion (H-DPhe-Gln-Trp-Ala-Val-Gly-His-NH-CH[CH2-CH(CH3)2]-CHOH-(CH 2)3-CH3, JMV845, was among the most potent compounds with ED50 of 7.82 +/- 2.89 nM in inhibiting bombesin-induced protein secretion). The results of this study showed that replacing the peptide bond between the two last amino acid residues in bombesin by mimicking the transition state analog resulted in in vitro and in vivo potent bombesin receptor antagonists.

Biological activity and three-dimensional structure of an agonist analog of bombesin

JMV635, a nonapeptide analog of the active terminal nonapeptide segment of bombesin, was tested for its ability to stimulate in vitro amylase release from rat pancreatic acinar cells and to inhibit the binding of gastrin-releasing peptide to rat pancreatic acini. It was found to be a full agonist of bombesin and to recognize the bombesin receptor with moderate potency. The NMR proton assignments of JMV635 were achieved, and the conformations of JMV635 in aqueous solution and in trifluoroethanol at 297 K were determined using two-dimensional COSY, HOHAHA, NOESY and ROESY experiments. In trifluoroethanol, JMV635, like the active part of bombesin, showed a partial alpha-helical structure. These results were confirmed by circular dichroism and refined by restrained molecular dynamic methods. Structure calculations, using the distance and angle restraints obtained from NMR data on JMV635, gave a total of 75 structures which could be aligned to a root mean square deviation of the bond length of 0.007 A and of the valence angle of 1.55 degrees for the backbone atoms of the amino acid residues. The conformation is a well-defined right-handed alpha-helix in the C-terminal Q2-G6 segment and is less structured in the three C-terminal residues.

Melanin-concentrating hormone binding sites in human SVK14 keratinocytes

Melanin concentrating hormone (MCH) is a cyclic peptide which regulates a broad array of functions in the mammalian brain and it may act as a paracrine factor in peripheral organs. In these studies a radiolabeled MCH derivative, the [125I]-[Phe13, Tyr19]-MCH, was synthesized and used as a tracer to perform binding experiments. A number of human or rodent cell lines displayed specific binding with [125I]-[Phe13, Tyr19]-MCH, the highest binding capacity being observed with human SVK14 keratinocytes. Saturation binding analysis with SVK14 cells indicated about 10,000 MCH binding sites per cell and a Kd of 0.7 nM for [125I]-[Phe13, Tyr19]-MCH. Surprisingly, the iodinated [Phe13, Tyr19]-MCH displayed about 10-fold higher affinity (Ki approximately 3.0 nM) for the putative MCH receptor than the noniodinated form (Ki approximately 25-30 nM). Competition binding analyses comparing various MCH-related peptides revealed a similar low binding potency for all these peptides (Ki approximately 65-160 nM). Strikingly, rat ANP and rat/human CNP but not rat BNP displaced [125I]-[Phe13, Tyr15]-MCH with Ki approximately 210-365 nM and may be due to topological similarities instead of partial sequence identities between MCH and some of the natriuretic peptides. However, other peptides such as CRF, alpha MSH, Arg-vasopressin, and MGOP-peptide I did not compete with the radioligand. Finally, the molecular mass of the MCH binding sites on SVK14 cells was estimated to be 47 kDa by crosslinking and SDS-PAGE experiments. Taken together, our data revealed the widespread expression of MCH binding sites on mammalian cells, particularly on skin carcinoma cells. However, the low affinity of these sites for the native MCH and MCH-related peptides as well as competitivity with ANP and CNP indicates that further biochemical and functional characterizations are needed to validate them as genuine physiological MCH receptors.

A new biological contribution of cyclo(His-Pro) to the peripheral inhibition of pancreatic secretion

The tripeptide pyro-Glu-His-Pro-NH2[thyrotropin-releasing hormone (TRH)] was isolated from the hypothalamus as a thyrotropin-releasing factor. It has a broad spectrum of central nervous system-mediated actions, including the stimulation of exocrine pancreatic secretion. TRH is also synthesized in the endocrine pancreas and found in the systemic circulation. Enzymatic degradation of TRH in vivo produces other bioactive peptides such as cyclo(His-Pro). Because of the short half-life of TRH and the stability of cyclo(His-Pro) in vivo, we postulated that at least part of the peripheral TRH effects on the exocrine pancreatic secretion may be attributed to cyclo(His-Pro), which has been shown to have other biological activities. This study determines in parallel the peripheral effects of TRH and cyclo(His-Pro) as well as the putative contribution of other TRH-related peptides on exocrine pancreatic secretion in rats. TRH and its metabolite cyclo(His-Pro) dose dependently inhibited 2-deoxy-D-glucose (2-DG)-stimulated pancreatic secretion. TRH and all the related peptides tested had no effect on the basal and cholecystokinin-stimulated amylase release from pancreatic acinar cells in vitro. These data indicate that cyclo(His-Pro) mimics the peripheral inhibitory effect of TRH on 2-DG-stimulated exocrine pancreatic secretion. This effect is not detected on isolated pancreatic acini. Our findings provide a new biological contribution for cyclo(His-Pro) with potential experimental and clinical applications.

Social work at the emergency department

We have evaluated the level of satisfaction of patients assigned to a social worker whose role was to give information, support, advice, grief and shock counselling; and develop resource strategies for marginal peoples. Six hundred patients were admitted to the study; 300 of them were supervised by a social worker (group A) and the other 300 were not (group B). After the completion of the study, a questionnaire was sent to be filled in by group A and group B for later evaluation. We collected 200 completed questionnaires (33.3%). The most important areas were: 105 patients (94.5%) in group A vs. 73 patients (82%) (p < 0.005) consider the medical care good or very good. The waiting time was assessed as short or acceptable in 91 patients (81.9%) in group A vs. 55 patients (61.8%) in group B (p < 0.001). The psychosocial care was assessed as very good or good in 101 patients group A (90.9%) vs. 73 patients in group B (82%) (p < 0.5).

[Intraneural synovial cyst of the peroneal nerve. Case report]

The authors report the case of an intraneural synovial cyst of the peroneal nerve. The initial symptom was pain and weakness of dorsiflexion and eversion of the right foot. The patient was operated on and the cyst was totally resected. The authors discuss the pathogenesis, clinical diagnosis as well as the treatment of that uncommon lesion.

Effect of antipanic treatment on response to carbon dioxide

BACKGROUND

Disordered breathing among patients with panic disorder, including hyperventilation during attacks and increased anxiogenic response to carbon dioxide (CO2) inhalation, is well established. We wished to assess whether there is a change in the physiological response to CO2 after patients have undergone antipanic therapy with either tricyclic antidepressants or cognitive behavioral therapy (CBT).

METHODS

Twenty-nine patients with panic disorder underwent baseline CO2 sensitivity testing using the traditional Read rebreathing method and then received either antidepressant treatment (n = 21) or CBT (n = 8). After completing treatment, CO2 testing was repeated. A comparison sample of 14 normal volunteers also had two CO2 sensitivity tests, separated by an average of 21.6 (SD = 8.8) weeks.

RESULTS

Using a liberal standard, in which all CO2 sensitivity tests whose correlations between minute ventilation and end-tidal CO2 were at least .75 were used, patients, but not controls, demonstrated a significant reduction in CO2 sensitivity between the first and second test. Using a more conservative .90 correlation standard reduced the sample size available and resulted in trend reduction in patients but no significant change in controls. There was a suggestion that the change was most pronounced in treatment responders, although the number of patient nonresponders is extremely small in this sample.

CONCLUSIONS

These data indicate that treatment reduces CO2 sensitivity in patients with panic disorder. We speculate that manipulation of the serotonergic and noradrenergic neurotransmission systems, both known to play a role in the control of respiration, may have a specific effect in reducing respiratory hyperactivity in panic disorder.

Cloning and high level expression of Cynodon dactylon (Bermuda grass) pollen profilin (Cyn d 12) in Escherichia coli: purification and characterization of the allergen

BACKGROUND

Profilin, an actin-binding protein, was previously described as a panallergen which is involved in about 20% of the crossreactivity found among pollen and food allergic patients. This allergen is usually under-represented in natural extracts used for allergy diagnosis.

OBJECTIVES

To obtain an immunologically active and soluble recombinant profilin from Cynodon dactylon pollen which could be used for diagnostic and therapy.

METHODS

Isolation of cDNA clones was performed by polymerase chain reaction amplification using degenerate primers. Expression in Escherichia coli BL21 (DE3) was carried out using vector pKN172, and the expressed product was isolated by affinity chromatography on poly L-proline-Sepharose.

RESULTS

Four cDNA inserts coding for Cynodon dactylon (Bermuda grass) pollen profilin (Cyn d 12) were cloned and sequenced. Full-length C. dactylon profilin gene was expressed in Escherichia coli as non fusion protein. Induced cells could produce high amounts of recombinant Cyn d 12, and after a single purification step on poly (L-proline)-Sepharose, up to 45 mg of pure allergen per litre culture could be obtained. The reactivity of recombinant Cyn d 12 with IgE antibodies present in sera from Bermuda grass-allergic patients is comparable to that of the natural Bermuda grass allergen. Recombinant Bermuda grass pollen profilin was shown to share B-epitopes with sunflower profilin.

CONCLUSIONS

Our results showed that this heterologous expression system and purification procedure are suitable for the production of large amounts of pure allergen which can be used for the characterization of allergenic epitopes recognized by T and B cells and finally for diagnostic and therapeutic purposes.

Role of prostaglandin H synthase-2-mediated conversion of arachidonic acid in controlling 3T6 fibroblast growth

The specific role(s) of arachidonic acid (AA) and its metabolites in the signaling pathways that regulated fibroblast growth was studied. A Western blot analysis demonstrated that prostaglandin H synthase-2 (PGHS-2) was expressed by 3T6 fibroblast cultures in RPMI 1640 supplemented with fetal calf serum (10%). Dexamethasone, which inhibits AA release and PGHS-2 expression, significantly reduced cell proliferation. Ketoprofen, a dual cyclooxygenase inhibitor, and CGP-28238, a specific PGHS-2 inhibitor, reduced fibroblast proliferation in a dose-dependent manner. These drugs also reduced [3H]thymidine incorporation into the DNA of fibroblasts. These effects were correlated with a decrease in prostaglandin (PG) E2 levels in the cell medium. However, piroxicam at doses that selectively inhibit PGHS-1 did not have a significant effect on fibroblast proliferation. Finally, we showed that the antiproliferative effect of dexamethasone and PGHS-2 inhibitors was significantly antagonized when PGE2 was added to the culture medium. Our results suggest that PGHS-2 and prostaglandins such as PGE2 might play an important role in the regulation of 3T6 fibroblast growth stimulated by growth factors of serum.