Sexual quality of life of adolescents and young adult breast cancer survivors.

BACKGROUND: With increasing survival rates of adolescents and young adults (AYAs) with breast cancer, health-related quality of life (HRQoL) becomes more important. An important aspect of HRQoL is sexual QoL. This study examined long-term sexual QoL of AYA breast cancer survivors, compared sexual QoL scores with that of other AYA cancer survivors, and identified factors associated with long-term sexual QoL of AYA breast cancer survivors. MATERIALS AND METHODS: Data of the SURVAYA study were utilized for secondary analyses. Sexual QoL was assessed using the European Organization for Research and Treatment of Cancer Quality of Life cancer survivorship core questionnaire (EORTC QLQ-SURV100). Descriptive statistics were used to describe sexual QoL of AYA cancer survivors. Linear regression models were constructed to examine the effect of cancer type on sexual QoL and to identify factors associated with sexual QoL. RESULTS: Of the 4010 AYA cancer survivors, 944 had breast cancer. Mean sexual QoL scores of AYA breast cancer survivors ranged from 34.5 to 60.0 for functional domains and from 25.2 to 41.5 for symptom-orientated domains. AYA breast cancer survivors reported significantly lower sexual QoL compared to AYA survivors of other cancer types on all domains. Age, time since diagnosis, relationship status, educational level, chemotherapy, hormonal therapy, breast surgery, body image, and coping were associated with sexual QoL of AYA breast cancer survivors. CONCLUSIONS: AYA breast cancer survivors experience decreased sexual QoL in the long term (5-20 years) after diagnosis and worse score compared to AYA survivors of other cancer types, indicating a clear need to invest in supportive care interventions for those at risk, to enhance sexual well-being.

Conjunctival provocation with airborne allergen in patients with atopic keratoconjunctivitis.

BACKGROUND: Atopic keratoconjunctivitis (AKC) is a chronic eye disease with periods of exacerbations. Many patients experience no obvious seasonal variation, although a majority of patients are allergic to common airborne allergens. OBJECTIVE: To investigate the allergic reaction, to conjunctival provocation with airborne allergens, in patients with AKC. METHODS: Eleven patients with AKC and birch and/or grass pollen allergy participated in the study, which was performed outside the pollen season. Five patients with seasonal allergic conjunctivitis (SAC) and five healthy subjects were included for validation purposes. The challenge was performed in one eye with the allergen, to which the patient was reactive, and with dilution buffer in the other eye. Signs and symptoms from both eyes were graded at baseline and at 10 min, 8 and 48 h after provocation. Tear fluid was collected from both eyes for cytokine analyses at baseline and at 8 and 48 h. RESULTS: A significant change in clinical symptoms and signs, (redness and chemosis) was evident 10 min after provocation compared with baseline (P = 0.005) and compared with the unprovoked eye (P = 0.005) in AKC subjects. These parameters were normalized after 8 and 48 h. A significant increase for IFN-γ (P = 0.021) and IL-6 (P = 0.015), and a near significant increase for IL-10 (P = 0.066) were seen in the tear fluid of the challenged eye at 48 h after provocation vs. baseline and vs. the control eye for IFN-γ (P = 0.005), IL-6 (P = 0.028) and IL-10 (P = 0.008) in AKC subjects. CONCLUSION AND CLINICAL RELEVANCE: In this single dose allergen provocation study, AKC patients responded with a typical IgE-mediated allergic reaction. An increase in cytokines at 48 h after the challenge was demonstrated and might, with further studies, give us a better understanding of the nature of inflammation in AKC.

Lymphoscintigraphy and SPECT/CT in multicentric and multifocal breast cancer: does each tumour have a separate drainage pattern? Results of a Dutch multicentre study (MULTISENT).

PURPOSE: To investigate whether lymphoscintigraphy and SPECT/CT after intralesional injection of radiopharmaceutical into each tumour separately in patients with multiple malignancies in one breast yields additional sentinel nodes compared to intralesional injection of the largest tumour only. METHODS: Patients were included prospectively at four centres in The Netherlands. Lymphatic flow was studied using planar lymphoscintigraphy and SPECT/CT until 4 h after administration of (99m)Tc-nanocolloid in the largest tumour. Subsequently, the smaller tumour(s) was injected intratumorally followed by the same imaging sequence. Sentinel nodes were intraoperatively localized using a gamma ray detection probe and vital blue dye. RESULTS: Included in the study were 50 patients. Additional lymphatic drainage was depicted after the second and/or third injection in 32 patients (64%). Comparison of planar images and SPECT/CT images after consecutive injections enabled visualization of the number and location of additional sentinel nodes (32 axillary, 11 internal mammary chain, 2 intramammary, and 1 interpectoral. A sentinel node contained metastases in 17 patients (34%). In five patients with a tumour-positive node in the axilla that was visualized after the first injection, an additional involved axillary node was found after the second injection. In two patients, isolated tumour cells were found in sentinel nodes that were only visualized after the second injection, whilst the sentinel nodes identified after the first injection were tumour-negative. CONCLUSION: Lymphoscintigraphy and SPECT/CT after consecutive intratumoral injections of tracer enable lymphatic mapping of each tumour separately in patients with multiple malignancies within one breast. The high incidence of additional sentinel nodes draining from tumours other than the largest one suggests that separate tumour-related tracer injections may be a more accurate approach to mapping and sampling of sentinel nodes in patients with multicentric or multifocal breast cancer.

Radio guided occult lesion localization (ROLL) for non-palpable invasive breast cancer.

BACKGROUND: Wire guided localization (WGL) for non-palpable breast cancer is technically difficult and patient unfriendly. Radio guided occult lesion localization (ROLL) takes advantage of the possibility to detect the tumor through the nuclear tracer that is injected directly into the tumor for the sentinel node procedure. METHODS: Forty patients with 41 invasive breast carcinomas were treated using ROLL. Patients received a dose of 120 Mbq 99mTc Nanocolloid intra-tumorally on the day of surgery or a dose of 370 Mbq 99mTc Nanocolloïd intra-tumorally the prior day. The sentinel node (SN) was located using patent blue and a gamma ray detection probe that was also employed to guide the tumor excision. RESULTS: In 31 patients (78%) the invasive tumor was adequately excised. In two cases (5%) a re-excision was required due to inadequately excised carcinoma in situ and in three patients (7.5%) both the invasive and the in situ tumor were inadequately excised. In 35 patients (88%) the SN was found and removed. CONCLUSIONS: The ROLL procedure seems to be an alternative to WGL in patients with non-palpable breast carcinoma. To determine the place of ROLL versus WGL in the treatment of non-palpable breast cancer, a randomized clinical trial is needed.

Radiofrequency ablation for breast cancer: a review of the literature.

INTRODUCTION: Radiofrequency ablation (RFA) provides an effective technique for minimally invasive tissue destruction. A novel application is the use for treatment of small breast carcinoma. METHODS: A broad search was conducted in Pubmed, Embase and the Cochrane library. Results of the relevant articles were analysed. RESULTS: The analysed studies were all feasibility or pilot studies using different patient and tumour characteristics and ablation settings. Despite many methodological differences, high percentages of complete tumour ablation varying between 80% and 100% were reported. CONCLUSION: Radiofrequency ablation is a promising new tool for minimally invasive ablation of small carcinomas of the breast. A large randomized control study is required to assess the long-term advantages of RFA compared to the current breast conserving therapies.

Not only Th2 cells but also Th1 and Th0 cells express CD30 after activation.

To investigate whether the CD30 molecule, expressed only by a minority of T and B cells, defines a subtype of T helper cells, Pityrosporum orbiculare-specific CD4+ T cell clones were assessed for CD30 protein and gene expression. The clones were defined as Th1, Th0, and Th2 according to their cytokine mRNA profile detected by reverse transcription PCR (RT-PCR). The kinetics of CD30 expression after OKT3 (anti-CD3) stimulation was analyzed by flow cytometry, immunocytochemistry, and RT-PCR. OKT3 activation induced a high expression of CD30 in cells of both Th1 and Th0 as well as Th2 type after 1-3 days. A difference between the clones was noted in that the Th2 clones remained highly positive in CD30 expression, whereas expression in the other clones started to decline from day 3. These data indicate that CD30 is expressed in activated CD4+ T cells of all three subtypes, and that the expression is sustained in Th2 cells.

Simultaneous use of an (125)I-seed to guide tumour excision and (99m)Tc-nanocolloid for sentinel node biopsy in non-palpable breast-conserving surgery.

PURPOSE: In the present study we describe patients with non-palpable breast lesions, in which an Iodine-125 ((125)I)-marker (or "seed") for excision of the primary tumour and Technetium-99m nanocolloid ((99m)Tc-nanocolloid) for sentinel node biopsy (SNB) are used simultaneously. The purpose was to investigate any interference between (125)I-seeds and (99m)Tc-nanocolloid by an in vitro and in vivo analysis. METHODS: Contrast/interference-ratios between (125)I and (99m)Tc count-rates were determined in vitro using a realistic simulation model. Measurements were performed with 3 gamma-probes with different crystal materials. In 25 consecutive patients (99m)Tc-nanocolloid was intratumourally administered at the site of a previously implanted (125)I-seed. Respectively, the (125)I-setting and (99m)Tc-setting of the gamma-probe guided the wide local excision and SNB and maximum counts-per-second (cps) were measured. RESULTS: In vitro the different probes varied in (125)I- and (99m)Tc-sensitivity. The contrast-ratio between (125)I and (99m)Tc in the (125)I-channel was 4.6 for a 3-month-old (125)I-seed using the most appropriate gamma-probe. In vivo the gamma-probe in the (125)I-setting measured a median of 16,300 cps at the tumour site compared to 4820 cps using the (99m)Tc-setting. The (125)I-seed could be well distinguished from the (99m)Tc-nanocolloid in 92% of the patients and 96% required a single operation. The SNB was successful in all patients. CONCLUSIONS: Simultaneous use of (125)I-seeds and (99m)Tc-nanocolloid is possible under well-standardised conditions. Non-palpable breast lesions can be safely excised using the (125)I-seed in combination with a SN procedure. Use of (125)I-seeds is a next step within fine-tuning breast-conserving surgery that should lead to further investigation to confirm its value.

CD3/T-cell receptor coupling to a pertussis and cholera toxin-insensitive G-protein.

We have analyzed the effect of CD3/T-cell receptor stimulation on GTP hydrolysis and GTP binding. We show that stimulation of Jurkat, T-cell, membranes with OKT3 results in a 50% increase in GTP hydrolysis which is specifically inhibited by GDP. Pretreatment of the membranes with neither pertussis toxin nor cholera toxin inhibited the GTP hydrolysis. We also show that stimulation with OKT3 increases the binding of GTP gamma S to Jurkat membranes. These data strongly implicate the involvement of a G-protein in CD3/T-cell receptor signalling.

cDNA analysis of the mite allergen Lep d 1 identifies two different isoallergens and variants.

For the first time the complete cDNA encoding two isoallergens of the non-pyroglyphid dust mite Lepidoglyphus destructor, Lep d 1, allergen has been sequenced. In addition, one of the isoallergens was found to have two variants. Oligonucleotides were designed from known amino acid sequences. The cDNA sequences were obtained by hybridizing these primers to mRNA and enhancement by the RT-PCR technique. To obtain the different complete encoding cDNA sequences and eliminate heteroduplex artifacts, we performed PCR + 1 reactions. Comparison of the amino acid sequence of the allergen shows leader sequences of 16 amino acids for both isoforms.

Limited distribution of pertussis toxin in rat brain after injection into the lateral cerebral ventricles.

In vivo administration of pertussis toxin is often used to study the involvement of guanine nucleotide binding proteins in signal transduction. Especially when it is administered in the brain the effect is often poor. This could be due to the fact that pertussis toxin does not reach the area of interest. To evaluate the extent to which pertussis toxin is distributed in rat brain after intraventricular injection, different techniques were used. Immunohistochemical studies with an antibody against pertussis toxin showed that immunoreactivity was limited to periventricular brain structures less than 0.5 mm from the lumen. The highest immunoreactivity was seen 16-24 h after injection. After 96 h the labeling was very weak. The proportion of guanine nucleotide binding proteins that were ADP-ribosylated by in vivo injection of pertussis toxin into the ventricles as assessed by in vitro [32P]-back-ADP-ribosylation was very low 48 h after the injection, in all regions studied. Direct injection of pertussis toxin into the brain caused a marked ADP-ribosylation localized to the region injected that was maximal at 72 h after injection. At 96 h there were also effects after control injections, indicating non-specific effects. Synaptosomal membranes and other membranes were equally affected by pertussis toxin. The results suggest that in studies regarding the effect of pertussis toxin treatment on signal transduction, the toxin must be injected very close to the brain region of interest and, furthermore, that the rats should be killed 48-72 h after injection. In case of lack of effect on the response of interest one should examine whether the ADP-ribosylation of pertussis toxin-sensitive guanine nucleotide binding proteins in the area of concern has been affected.

Basal and cocaine-induced opioid receptor gene expression in the rat CNS analyzed by competitive reverse transcription PCR.

The basal mRNA levels of kappa and mu opioid receptors, as well as their regulation after 'binge' cocaine administration, were determined with competitive reverse transcription polymerase chain reaction (RT-PCR) in brain regions of male Sprague-Dawley rats. The procedure proved to be a reliable method to quantify the relative opioid receptor gene expression. The highest basal mRNA levels for the kappa opioid receptor were found in the nucleus accumbens and hypothalamus, whereas the highest basal mRNA expression for the mu opioid receptor was observed in the hypothalamus. Rats were separately treated with 'binge' (three hourly injections) cocaine HCl (45 mg/kg/day i.p.) or saline (1 ml/kg i.p.) for 2 days. A significant down-regulation of the kappa opioid receptor mRNA was detected in the nucleus accumbens. The mu opioid receptor mRNA was not affected. The data suggest a selective effect on kappa receptor expression in the nucleus accumbens as a consequence of 'binge' cocaine use.

Evidence for functionally important adenosine A2a receptors in the rat hippocampus.

Adenosine A2a receptors are not confined to dopamine-rich areas of the brain, since thermocycling analysis shows that adenosine A2a receptor mRNA is expressed also in the hippocampus (CA1, CA3 and dentate gyrus) and cerebral cortex. The expression of A2a mRNA in three main areas of the hippocampus was confirmed by in situ hybridization; A2a mRNA expression was mainly localized in the pyramidal and granular cells, the same hippocampal regions that showed adenosine A1 receptor mRNA expression. Receptor autoradiographic studies with [3H]CGS 21680 (30 nM), a selective adenosine A2a receptor agonist, showed specific binding sites in the hippocampus. The density of [3H]CGS 21680 binding was greatest in the stratum radiatum of the CA1 area, followed by the stratum oriens of the cornu Ammonis, stratum radiatum of the CA3 are and supra-granular layer of the dentate gyrus. This anatomical distribution of [3H]CGS 21680 binding was similar to the pattern of [3H]CHA binding in the hippocampus. Electrophysiological studies in the Schaffer fibers/CA1 pyramids showed that upon activation of the A2a receptors with CGS 21680 (10 nM) the ability of the adenosine A1 receptor agonist, CPA, to inhibit neuronal activity was significantly attenuated. These results show functionally important co-expression and co-localization of adenosine A2a and A1 receptors in the hippocampus. The results also suggest that adenosine A2a receptor-mediated neuromodulation is not confined to the basal ganglia, but is more widespread throughout the nervous system.

Dual effects of protein kinase-C on receptor-stimulated cAMP accumulation in a human T-cell leukemia line.

In the human T-cell leukemia line Jurkat, cAMP accumulation stimulated by the adenosine receptor agonist 5'-N-ethylcarboxamido adenosine (NECA) was enhanced by tumour-promoting phorbol esters whereas the prostaglandin receptor-stimulated accumulation of cAMP was antagonized. Phorbol esters did not alter the adenosine or prostaglandin receptor-stimulated accumulation of cAMP in cells in which the phospholipid/Ca2+-dependent protein kinase (protein kinase-C) was down-regulated. cAMP stimulation induced by cholera toxin (CT) was enhanced by phorbol esters by 100-300%. The cAMP production induced by forskolin was never enhanced by more than 50% by 4 beta-phorbol-12,13-dibutyrate (PDBu) and there was no stimulation at all after down-regulation of the adenosine receptor by treatment with NECA. Phorbol ester enhanced the NECA-stimulated accumulation of cAMP, even in the presence of concentrations of forskolin that increased the cAMP accumulation several-fold. From these data we conclude that protein kinase-C can interact with receptors coupled to adenylate cyclase in a stimulatory as well as an inhibitory manner. Moreover, protein kinase-C appears to interact with signal transduction at two levels, one highly receptor-specific and one distal to the receptor.

Pertussis toxin treatment counteracts intramembrane interactions between neuropeptide Y receptors and alpha 2-adrenoceptors.

The effect of intracerebroventricular injections of pertussis toxin were investigated on the neuropeptide Y-induced modulation of alpha 2-adrenoceptor binding in membranes from the dorsomedial medulla oblongata of the rat. Concentration-response experiments showed that neuropeptide Y reduced the binding affinity of the alpha 2-agonist, p-[3H]aminoclonidine, with a maximal effect of 30% at 3-30 nM. Pertussis toxin treatment (10 micrograms, 24 h) counteracted this modulation, without reducing the binding of neuropeptide Y to its own receptor. The results indicate that pertussis toxin-sensitive G-proteins are essential for the mediation of the intramembrane interaction between neuropeptide Y receptors and alpha 2-adrenoceptors.

In vivo pertussis toxin treatment attenuates some, but not all, adenosine A1 effects in slices of the rat hippocampus.

In order to examine the involvement of G-proteins in mediating the different effects of adenosine A1-receptor stimulation in rat hippocampus we injected pertussis toxin (PTX) intraventricularly close to the hippocampus and examined its effect in slices 48-60 h later. The in vivo PTX treatment caused a partial (50 +/- 5%) inhibition of the [32P]ADP ribosylation produced by PTX added together with [32P]NAD in vitro. Such PTX treatment eliminated the electrophysiologically determined gamma-amino-n-butyric acid (GABA)B receptor response in the hippocampal CA1 region, but GABAA effects were unaffected. The adenosine (50 microM)-mediated hyperpolarization and decrease in input resistance as well as the adenosine-mediated inhibition of low calcium-induced bursting in pyramidal CA1 neurons were virtually abolished. The same was true for the decrease in [3H]cyclic AMP accumulation that is produced by the adenosine analogue R-N6-phenylisopropyl adenosine (R-PIA) in forskolin-treated hippocampal slices. As far as modulation of transmitter release was concerned, the R-PIA (1 microM)-induced inhibition of release of both [3H]noradrenaline (NA) and [3H]acetylcholine (ACh) evoked by field stimulation in hippocampal slices was affected hardly or not at all by pertussis toxin treatment. The inhibitory effect of adenosine on field excitatory postsynaptic potential (EPSP)s evoked in the CA1 region was unaltered by PTX pretreatment. The present results show that in vivo pertussis toxin treatment can inhibit some but not all A1-adenosine-receptor effects. This strongly suggests that closely similar A1 receptors might be coupled to G-proteins that differ in their sensitivity to PTX treatment.

Stimulation of the T-cell receptors CD3 and CD2 with OKT3 and OKT11 antibodies activates a common pertussis toxin-insensitive G-protein.

The association of G-proteins with the T-cell-specific receptor structures CD3 and CD2 was investigated. High-affinity GTPase activity in membrane preparations of the human leukemic T-cell line Jurkat could be induced by the monoclonal antibodies OKT3 (anti-CD3) and OKT11 (anti-CD2). When combining maximally active concentrations of OKT3 and OKT11, no additive effect was seen on GTPase activity. In mutant Jurkat cells lacking the CD3 complex but with an intact CD2 receptor, neither OKT3 nor OKT11 could stimulate GTPase activity. Activation of CD3 and CD2 by monoclonal antibodies also stimulated phospholipase C activity as measured by breakdown of membrane phosphoinositides in wild-type but not in mutant Jurkat cells. Neither GTPase nor phospholipase C activation was sensitive to pretreatment with doses of pertussis toxin (PTX) that caused ADP ribosylation of a sensitive G-protein. Our data show that the CD3 complex and the CD2 receptor may activate a common PTX-insensitive G-protein. The CD2 receptor appears to stimulate the G-protein by interacting with the CD3 complex. The data are compatible with, but do not prove, that this G-protein is involved in the activation of phospholipase C by the two receptors.

Pertussis toxin treatment counteracts the cardiovascular effects of neuropeptide Y and clonidine in the awake unrestrained rat.

The role of G-proteins in the mediation of the cardiovascular effects of neuropeptide Y and the alpha 2-adrenoceptor agonist clonidine was investigated by injections of pertussis toxin (10 micrograms/30 microliters, i.v.t., 24 h) in the awake unrestrained male rat. Treatment with pertussis toxin was found to inhibit the hypotensive and bradycardic actions of neuropeptide Y (1250 pmol) and the hypotensive actions of clonidine (1875 pmol). Control experiments showed that treatment with pertussis toxin caused an approximately 50% reduction in the back-ADP-ribosylation of GTP-binding proteins. These results suggest that G-proteins mediate the central cardiovascular actions of neuropeptide Y and clonidine.

Intracerebroventricularly administered pertussis toxin blocks the central vasopressor action of neuropeptide Y(13-36) in the awake unrestrained male rat.

The effects of intracerebroventricular (i.v.t.) injections of pertussis toxin (PTX) (10 micrograms/30 microliters, 48 h) were studied on the cardiovascular actions of i.v.t. administered neuropeptide Y(13-36) (NPY(13-36)) as evaluated in the awake unrestrained male rat. The vasopressor action of NPY(13-36) in the peak dose of 3000 pmol per rat was significantly inhibited by pretreatment by PTX. Pertussis toxin treatment alone significantly reduced the baroreceptor reflex elicited by L-phenylephrine. The results are compatible with the view that G-proteins mediate the central vasopressor actions of NPY(13-36) and thus probably are involved in NPY Y2-receptor transduction in cardiovascular areas of the brainstem.

Adenosine A2A receptors mediate the inhibitory effect of adenosine on formyl-Met-Leu-Phe-stimulated respiratory burst in neutrophil leucocytes.

Using the reverse transcription polymerase chain reaction (RT-PCR) we found that human neutrophils express mRNA for both A2A and A2B adenosine receptors, and using selective adenosine receptor agonists and antagonists we have characterized the type of adenosine receptor mediating inhibition of formyl-Met-Leu-Phe (fMLP)-induced oxidative burst. The order of potency of agonists was 5'-N-ethyl-carboxamidoadenosine (NECA) > 2-phenylaminoadenosine > 2-[p-(2-carbonyl-ethyl)-phenyl-ethylamino]-5'-N-ethyl-carboxamido adenosine (CGS 21680) > adenosine > N6-cyclopentyl-adenosine. This agrees with the agonist potency at human A2A receptors. The effect of adenosine was antagonized by 30 microM theophylline > caffeine = paraxanthine, i.e. concentrations close to those occurring in plasma after consumption of caffeine-containing beverages. The effect of NECA was unaltered by the A1 receptor antagonist 1,3-dipropyl-8-cyclopentylxanthine, but inhibited by the A2A receptor selective antagonists 4-amino-8-chloro-1-phenyl-[1,2,4]-triazolo[4,3-a]quinoxaline (CP 66,713), 1,3-dipropyl-8-(3,4-dimethoxystyryl) -7-methylxanthine (KF 17387) and 8-(3-chlorostyryl)caffeine as well as by the non-selective, non-xanthine antagonist 5-amino-9-chloro-2-(2-furyl)-[1,2,4]-triazolo-[1,5-c]quinazoline methane sulphonate (CGS 15943). The adenosine receptor mediated responses were antagonized by the protein kinase A blocker Rp-cyclic adenosine 3',5'-phosphorothioate (Rp-cAMP). In conclusion, the adenosine-induced inhibition of neutrophil activation is mediated by adenosine A2A receptors.

Role of a pertussis toxin sensitive G-protein in mediating the effects of phorbol esters on receptor activated cyclic AMP accumulation in Jurkat cells.

In the human T-cell line, Jurkat, the accumulation of cyclic AMP induced by adenosine is enhanced by tumor-promoting phorbol esters, whereas prostaglandin E2 receptor-stimulated cAMP accumulation is antagonized (Nordstedt et al. 1989). In the present study we examine the involvement of pertussis toxin sensitive guanine nucleotide binding proteins (G-proteins) in producing the phorbol ester effects. Pertussis toxin pretreatment of the Jurkat cells invariably caused an ADP ribosylation of two G-proteins that inhibit adenylyl cyclase, tentatively identified as Gi2 and Gi3, using Western blots. Pertussis toxin treatment had little effect on basal cAMP accumulation, but sometimes inhibited, sometimes stimulated agonist and cholera toxin induced cAMP accumulation. The latter effect was not mimicked by the B-oligomer. Irrespective of whether pertussis toxin stimulated or inhibited NECA and cholera toxin-induced cAMP accumulation it could not block the effect of phorbol-12,13-dibutyrate (PDBu). The inhibitory effect of PDBu on prostaglandin E2-induced cAMP accumulation was, however, invariably eliminated by pertussis toxin treatment. In conclusion, activation of protein kinase C by phorbol esters reveals a Gi-mediated prostaglandin E receptor-induced inhibition of adenylate cyclase in addition to the prostaglandin E receptor-mediated stimulation of cAMP accumulation in Jurkat cells. The enhancement of adenosine A2 receptor stimulated cAMP accumulation by PDBu, on the other hand, does not involve a PTX sensitive Gi-protein.