Efficacy of chimeric molecules directed towards multiple somatostatin and dopamine receptors on inhibition of GH and prolactin secretion from GH-secreting pituitary adenomas classified as partially responsive to somatostatin analog therapy.

OBJECTIVE: This study compared the potency of a somatostatin receptor (sstr)2-sstr5 analog, BIM-23244, of an sstr2-dopamine D2 receptor (sstr2-DAD2) molecule, BIM-23A387 and of new somatostatin-dopamine chimeric molecules with differing, enhanced affinities for sstr2, sstr5 and DAD2, BIM-23A758, BIM-23A760 and BIM-23A761, to suppress GH and prolactin (PRL) from 18 human GH adenomas that are partially responsive to octreotide or lanreotide. MATERIALS AND METHODS: The sstr2, sstr5 and DAD2 mRNA levels were determined by RT-PCR. The effect of drugs was tested in cell cultures at various concentrations. RESULTS: In all tumors, the sstr2, sstr5 and DAD2 mRNA levels were coexpressed (mean levels+/-s.e.m. 0.4+/-0.1, 5.3+/-1.9 and 2.0+/-0.4 copy/copy beta-glucuronidase). In 13 tumors, the maximal suppression of GH secretion produced by BIM-23A387 (30+/-3%) and BIM-23244 (28+/-3%) was greater than that produced by octreotide (23+/-3%). In six out of 13 tumors, BIM-23A758, BIM-23A760 and BIM- 23A761 produced greater maximal suppression of GH secretion than octreotide (33+/-5, 38+/-2 and 41+/-2 vs 24+/-2%). Their EC(50) values were 10, 2 and 4 pmol/l. BIM-23A761 was more effective than BIM-23A387 in GH suppression (41+/-2 vs 32+/-4%). The new chimeric molecules produced maximal PRL suppression greater than octreotide (62+/-8 to 74+/-5 vs 46+/-11%). CONCLUSIONS: Novel dopamine-somatostatin chimeric molecules with differing, enhanced activity at sstr2, sstr5 and DAD2, consistently produced significatly greater suppression of GH and PRL than either octreotide or single-receptor-interacting ligands in tumors from patients classified as only partially responsive to octreotide therapy. The higher efficacy of the chimeric compounds was, at least partially, linked to their high affinity for sstr2 (IC50 1-10 pmol/l). The other mechanisms by which such molecules produce an enhanced inhibition of GH remain to be elucidated.

BIM-23A760, a chimeric molecule directed towards somatostatin and dopamine receptors, vs universal somatostatin receptors ligands in GH-secreting pituitary adenomas partial responders to octreotide.

We report the comparative efficacy of a somatostatin receptor 1 and 5 subtypes (SSTR2 and SSTR5), and dopamine D2 (DAD2) compound, BIM-23A760, in suppressing GH secretion, in cell culture from human GH-secreting tumors, from patients partially responsive to long-term treatments with octreotide or lanreotide. In 18 tumors tested, the SSTR2, SSTR5, and DAD2 mRNAs were coexpressed. The SSTR2-selective analog, BIM-23197, the SSTR5-selective analog, BIM-23268, and the dopamine (DA) analog, BIM-53097, produced a mean maximal suppression of GH secretion (24 +/- 3, 20 +/- 3, and 20 +/- 3%, respectively) that was similar to that obtained with octreotide (23 +/- 3%). Nevertheless, based on individual responses, 60% of the tumors were mostly sensitive to the SSTR2 analog while 19 and 21% of the tumors were mainly responsive to the SSTR5 analog and to the DA analog, respectively. Among a series of new chimeric compounds that bind the SSTR2, SSTR5, and DAD2 receptors with variable affinities, BIM-23A760 produced greater maximal suppression of GH secretion than octreotide (38 +/- 2 vs 24 +/- 2%; p<0.03). The EC50 for BIM-23A760 was 2 pmol/l. In the presence of sulpride, the dose response inhibition of GH secretion by the trihybrid molecule, BIM-23A760, was partially reversed. The trihybrid produced also a maximal suppression of PRL greater than octreotide (74 +/- 5 vs 46 +/- 11%). When SSTRs pan inhibitors such as BIM-23A779 (binding affinity for SSTR1, SSTR2, SSTR3, SSTR5, respectively: 2.5, 0.3, 0.6, 0.6 nmol/l) or SOM230 were tested for their suppressive effects on GH secretion, they were less potent than the previous dopastatin hybrid molecule. After a brief exposure to a SSTR2-selective analog, BIM-23197, or to a DA analog, BIM-53097, the maximal GH suppression was achieved during 12 h. Under exposure to BIM-23A760, in the same conditions, maximal suppression of GH secretion lasted for 24 h. Such a longer biological effect, yet not explained, probably participates in the higher efficacy of BIM-23A760. The higher efficacy of BIM-23A760 is, at least partially, linked to its high affinity for the SSTR2 receptor subtype (IC50: 3 pmol/l). As compared to the dopastatin compound, the lower efficacy of the universal somatostatin ligands in the inhibition of GH secretion of GH-secreting tumors argues for the use of drugs targeted, according to specific receptors expression and functionality which may vary among the various classes of tumors.

Somatostatin receptor subtypes: targeting functional and therapeutic specificity.

Somatostatin is a regulatory peptide involved in a wide variety of biological functions throughout the body. A key physiological question, as well as the challenge to developing somatostatin-based therapeutics, is how functional specificity can be conferred in such a widespread, multifunctional hormonal system. With the discovery of distinct subtypes of the somatostatin receptor, we have attempted to elucidate the manner in which somatostatin selectively regulates specific biological functions using panels of somatostatin analogs that have been fully characterized for their unique selectivity and specificity for the various receptor subtypes. By testing these selective analogs in well-established biological assay systems, we and our collaborators have revealed functional interactions between the somatostatin receptor subtypes that can either potentiate or antagonize the cellular response to somatostatin. These observations have resulted in several novel concepts for treating acromegaly that should offer greater efficacy to a larger percentage of patients than current therapeutic options. Further, these studies are providing evidence of interaction between the somatostatin receptor subtypes and receptors of other G-protein-coupled receptor families. These various levels of interaction provide a means by which the cellular response to somatostatin can be exquisitely controlled and modified by both physiological status and disease. Greater understanding of these interactions will provide the conceptual basis for future therapeutics with enhanced efficacy and with greater cellular and functional specificity.

Serum corticosterone and blood glucose in rats after two jugular vein blood sampling methods: comparison of the stress response.

The purpose of this study was to evaluate stress by comparing blood glucose and serum corticosterone levels after repeated blood sampling over 2 h (five time points) in anesthetized noncannulated rats to those of nonanesthetized jugular-cannulated animals. Noncannulated rats underwent isofluorane anesthesia for the duration of the blood sampling at each time point. For both sampling methods, blood glucose concentrations increased after the initiation of blood sampling, peaked at significantly increased (noncannulated rats, P < 0.01; cannulated rats, P < 0.01) concentrations at 0.5 h, and decreased thereafter until the end of the assessment period. Despite the observed fluctuations, blood glucose concentrations remained within normal ranges. Similarly, corticosterone concentrations increased significantly (noncannulated rats, P < 0.01; cannulated rats, P < 0.001) to peak values at 0.5 h. However, corticosterone was significantly lower at the 1- (P < 0.01) and 2-h (P < 0.05) time points in cannulated rats compared with anesthetized rats. Therefore, although both sampling methods are similar regarding blood glucose and corticosterone peak concentrations and time-to-peak, stress was slightly less in the cannulated rats than the rats that underwent repeated anesthesia.

Elevated glycemia and local inflammation after injecting N-methyl-2-pyrrolidone (NMP) into the marginal ear vein of rabbits.

The objective of this pilot study was to evaluate glycemia in rabbits by administering various vehicles for solubilizing poorly soluble candidate drugs used for the treatment of diabetes. Groups of three New Zealand White rabbits received intravenously: saline; 2.0 IU/kg insulin; 23 to 45% dimethyl acetamide (DMA)/10% cremophor (v:v) in water; or N-methyl-2-pyrrolidone (NMP). For the determination of glycemia, blood was collected just before and 0.25, 0.5, 1, 2, 4, and 24 h after injection. Glycemia after saline and DMA/cremophor injections remained stable and within the normal range (3.6 to 5.0 mmol/l). In insulin-injected rabbits, glycemia decreased (1 to 2 mmol/l) as expected. With NMP, glycemia was elevated (7.8 mmol/l), and animals were hyperactive upon injections. Injected ears gradually became bluish; 48 h after injection, they were edematous and necrotic. In conclusion, DMA/cremophor seems to be an acceptable vehicle. However, NMP may cause stress and local ear irritation when injected intravenously in rabbits.

Bim-23244, a somatostatin receptor subtype 2- and 5-selective analog with enhanced efficacy in suppressing growth hormone (GH) from octreotide-resistant human GH-secreting adenomas.

Although both somatostatin receptor subtype 2 (SSTR2) and SSTR5 messenger ribonucleic acid (mRNA) are consistently expressed in GH-secreting adenomas, SSTR2 has been believed to be the key modulator of somatostatin-mediated inhibition of GH release. The somatostatin agonists currently in clinical use, octreotide and lanreotide, are directed mainly to SSTR2 (IC(50) 12- to 18-fold higher than for SSTR5). Recently, however, it was demonstrated that an SSTR5 preferential agonist, BIM-23268, not only suppressed PRL release from prolactinomas and mixed GH-PRL adenomas, but also inhibited GH release in about half of GH adenomas. In addition, the SSTR5-preferring analog showed a slight additive effect when used in combination with SSTR2 preferential drugs at submaximal concentrations in octreotide partially sensitive adenomas. In the present study we quantified SSTR2 and SSTR5 mRNA expression and the GH-suppressive effects of somatostatin-14; octreotide; a SSTR2-preferential compound, BIM-23197; a SSTR5-preferential compound, BIM-23268; and a new SSTR2- and SSTR5-bispecific compound, BIM-23244, in GH-secreting tumors classified as either full responders to octreotide (n = 5) or partially sensitive to octreotide (n = 5). The octreotide-sensitive GH secretory adenomas presented with a high level of both SSTR2 and SSTR5 mRNA expression [222 +/- 61 and 327 +/- 136 pg/pg glyceraldehyde-3-phosphate dehydrogenase (GAPDH), respectively]. In these tumors the suppression of GH release was similarly achieved at picomolar ranges by octreotide, BIM-23197, and BIM-23244 (EC(50) = 25 +/- 15, 3 +/- 2, and 3 +/- 3 pmol/L, respectively). The compounds preferential for only SSTR5 were unable to inhibit GH release in such tumors. Among the octreotide partially responsive tumors, SSTR2 mRNA expression was 9-fold lower than in the octreotide-sensitive tumors (25 +/- 12 vs. 222 +/- 61 pg/pg GAPDH; P < 0.015), whereas SSTR5 mRNA expression was approximately 7-fold higher than in the octreotide-sensitive tumors (2271 +/- 1197 pg/pg GAPDH). In these octreotide partially responsive tumors, the SSTR5-preferential compound, BIM-23268, and the SSTR2- and SSTR5-bispecific compound, BIM-23244, were quite effective in suppressing GH secretion (EC(50) = 25 +/- 13 and 50 +/- 31 pmol/L, respectively). Similarly, BIM-23244, was able to suppress by 51 +/- 5% PRL release from five mixed GH- and PRL-secreting adenomas. These data indicate that due to heterogeneous expression of SSTR2 and SSTR5 receptor subtypes, in GH-secreting tumors, a bispecific analog, such as BIM-23244, that can activate both receptors could achieve better control of GH hypersecretion in a larger number of acromegalic patients.

A pharmacokinetic study of amoxycillin in febrile beagle dogs following repeated administrations of endotoxin.

The pharmacokinetics of amoxycillin was studied in nine male beagle dogs under healthy and febrile conditions. In Period 1, dogs received 20 mg/kg of an oral suspension of amoxycillin. Intravenous doses of saline, 2 and 20 microg/kg of endotoxin (LPS from Escherichia coli serotype) were administered to dogs (three per group) prior to administration of 20 mg/kg of amoxycillin in Period 2. Rectal temperature and behavioral changes were recorded and blood samples were collected over 12 h for pharmacokinetic analysis. Amoxycillin was assessed in plasma using liquid chromatography coupled with mass spectrometry. Plasma concentrations were analysed using a one-compartment model with lag-time for absorption using an iterative two-stage method. As compared with control groups, amoxycillin clearance decreased significantly with preliminary treatments of 2 microg/kg endotoxin (0.209 vs. 0.140 L/h kg, P < 0.05) and 20 microg/kg endotoxin (0.214 vs. 0.075 L/h kg, P < 0.05). As a result of this, the area under curve for the 2 and 20 microg/kg endotoxin groups increased significantly 100.4 vs. 149.4 microg h/mL (P < 0.05) and 99.2 vs. 277.7 microg h/mL (P < 0.05), respectively. Other drugs currently used for the treatment of fever and septic shock should be re-evaluated using a febrile animal model to avoid improper dose administration.

Drug-induced inhibition of the peripheral-type benzodiazepine receptor expression and cell proliferation in human breast cancer cells.

The peripheral-type benzodiazepine receptor (PBR) expression and localization correlate with human breast cancer cell proliferation and aggressive phenotype expression. The standardized extract of Ginkgo biloba leaves (EGb 761) and isolated ginkgolide B (GKB) were shown to decrease PBR mRNA expression in adrenal cells. We examined the effect of EGb 761 and GKB on PBR expression and cell proliferation in human breast cancer cells. EGb 761 and GKB decreased in a time- and dose-dependent manner PBR expression and cell proliferation in the highly aggressive, rich in PBR, human breast cancer cell line MDA-231 whereas they did not affect the proliferation of the non-aggressive human breast cancer cell line MCF-7, which contains very low PBR levels. This effect was reversible and not due to the antioxidant properties of the compounds tested. Using a human cDNA expression array we determined that EGb 761 treatment altered, in addition to PBR, the expression of 36 gene products involved in various pathways regulating cell proliferation. These in vitro data were further validated in an in vivo model where EGb 761 and GKB significantly inhibited the nuclear PBR expression and growth of MDA-231 cell xenografts in nude mice. Taken together, these data suggest that the manipulation of PBR expression could be used to control tumor growth and that EGb 761 and GKB, under the conditions used, exert cytostatic properties.

Stability-related studies on 17D yellow fever vaccine.

Yellow fever (YF) vaccine using the 17D strain of YF attenuated virus has been produced at the Institut Pasteur in Dakar since 1962. Until now, the stabilised YF had an expiry date of utilization of two years from the end of the lot control process under storage at +4 degrees C. We conducted a stability study to assess the three full year validity of this preparation, when correctly stored at +4 degrees C to optimise the conditions of production, storage and availability of such a vaccine. The activity of 19 consecutive batches of vaccines kept for three years at +4 degrees C was compared to that of the same batches that were kept three years at -20 degrees C. Using the in vitro microculture method, we found that three-year storage at +4 degrees C induced a higher loss of activity than storage at -20 degrees C or than the accelerated degradation test of vaccines kept for 14 days at 37 degrees C. Whatever the conditions of storage, in all cases decreases in activity were below the WHO's requirements, i.e., < 1 log PFU/dose, and residual activity of the selected batches was over 1000 mouse LD50 per dose. We demonstrated that the 17D YF vaccine produced in Dakar has a shelf-life of three years and that its required potency was maintained at +4 degrees C, after reconstitution with saline diluent, following three-year storage at +4 degrees C.

Human somatostatin receptor subtypes in acromegaly: distinct patterns of messenger ribonucleic acid expression and hormone suppression identify different tumoral phenotypes.

Recently, studies using somatostatin (SRIF) analogs preferential for either the SRIF receptor 2 (SSTR2) or the SSTR5 subtype demonstrated a variable suppression of GH and PRL release from GH-secreting human adenomas. These data suggested the concept of SSTR subtype specificity in such tumors. In the present study the quantitative expression of messenger ribonucleic acid (mRNA) for the 5 SSTR subtypes and the inhibitory effects of SRIF14; SRIF28; octreotide; the SSTR2-preferential analog, BIM-23197; and the SSTR5-preferential analog, BIM-23268, on GH and PRL secretion were analyzed in cells cultured from 15 acromegalic tumors. RT-PCR analysis revealed a consistent pattern of SSTR2 and SSTR5 mRNA expression. SSTR5 mRNA was expressed at a higher level (1052 +/- 405 pg/pg glyceraldehyde-3-phosphate dehydrogenase) than SSTR2 mRNA (100 +/- 30 pg/pg glyceraldehyde-3-phosphate dehydrogenase). However, only SSTR2 mRNA expression correlated with the degree of GH inhibition induced by SRIF14, SRIF28, and BIM-23197. The SSTR5-preferential compound inhibited GH release in only 7 of 15 cases. In cells cultured from the 10 mixed adenomas that secreted both GH and PRL, RT-PCR analysis revealed a consistent coexpression of SSTR5, SSTR2, and SSTR1 mRNA. In all cases SRIF14, SRIF28, and the SSTR5-preferential analog, BIM-23268, significantly suppressed PRL secretion, with a mean maximal inhibition of 48 +/- 4%. In contrast, the SSTR2-preferential analogs, BIM-23197 and octreotide, were effective in suppressing PRL in only 6 of 10 cases. In cells cultured from adenomas taken from patients partially responsive to the SRIF analog, octreotide, partial additivity in suppressing both GH and PRL secretion was observed when the SSTR2- and SSTR5-preferring analogs, BIM-23197 and BIM-23268, were tested in combination. Our data show a highly variable ratio of the SSTR2 and SSTR5 transcripts, according to tumors. The SSTR2-preferring compound consistently inhibits GH release, whereas the SSTR5-preferring compound is the main inhibitor of PRL secretion. When both drugs are combined, the partial additivity observed in mixed GH- plus PRL-secreting adenomas may be of interest in the therapeutic approach of such tumors.

Quantitative and functional expression of somatostatin receptor subtypes in human prolactinomas.

Recently, it was demonstrated that somatostatin analogs preferential for the SSTR5 subtype suppress PRL release from prolactinoma cell cultures by 30-40%. These data supported the idea of somatostatin receptor subtype-specific control of PRL secretion in such tumors. The present study examines the quantitative profile of SSTRs messenger ribonucleic acid (mRNA) in 10 PRL-secreting tumors and correlates the expression with the ability of native somatostatins (SS14 and SS28), SSTR2 preferential analogs (octreotide and BIM-23197), and the SSTR5 preferential analog BIM-23268 to suppress PRL secretion. RT-PCR quantitative analysis showed a large predominance of SSTR5 mRNA [5648 +/- 1918 pg/pg glyceraldehyde-3-phosphate dehydrogenase (GAPDH)] vs. SSTR2 mRNA (148 +/- 83 pg/pg GAPDH). The SSTR1 transcript was also highly expressed in prolactinomas (1296 +/- 669 pg/pg GAPDH). SSTR5 mRNA expression correlated with PRL inhibition induced by both SRIF14 and SRIF28. Among the different analogs tested, only BIM-23268 produced inhibition of PRL release similar to that achieved with the native peptides. Its EC50 for PRL suppression was 0.28 +/- 0.10 nmol/L. No additive effects on PRL suppression were achieved by cotreatment of the tumor cells with SSTR2 and SSTR5 preferential analogs. In the same tumor cell cultures, quinagolide, a potent dopamine agonist, produced a dose-dependent inhibition of PRL with an EC50 at least 10 times lower than that of BIM-23268. Coincubation of quinagolide and BIM-23268, particularly in tumor cells resistant to dopamine agonist treatment, did not produce additive effects on PRL suppression. In conclusion, prolactinomas have a specific pattern of SSTR subtype mRNA expression (SSTR5 and SSTR1). SSTR5 expression is correlated to PRL regulation. These inhibitory effects are superimposable, at a higher concentration, to those of the dopamine agonists, but are not additive, particularly in the adenomas resistant to dopaminergic suppression of PRL release.

Mother-to-child transmission of human T-cell-leukemia/lymphoma virus type I: implication of high antiviral antibody titer and high proviral load in carrier mothers.

In order to gain new insights into the risk factors influencing human-T-cell-leukemia/lymphoma-virus-type-I (HTLV-I) mother-to-child transmission, a retrospective study of HTLV-I infection among children born to HTLV-I-seropositive women was carried out in a highly HTLV-I-endemic population of African origin living in French Guyana. The study covered 81 HTLV-I-seropositive mothers and their 216 children aged between 18 months old and 12 years old. All plasma samples were tested for the presence of HTLV-I antibodies by ELISA, immunofluorescence assay and Western blot. HTLV-I provirus was detected, in the DNA extracted from peripheral-blood mononuclear cells, by polymerase chain reaction (PCR) using primers specific for 3 different HTLV-I genomic regions (LTR, gag and pX) and quantified by a competitive PCR assay. Out of the 216 children, 21 were found to be HTLV-I-seropositive, giving a crude HTLV-I transmission rate of 9.7%, while among the 180 breast-fed children 10.6% were HTLV-I-seropositive. Perfect concordance between serological and PCR results was observed, and none of the 195 HTLV-I-negative children was found HTLV-I-positive by PCR. In conditional (by family) logistic-regression models, HTLV-I seropositivity in children was associated with an elevated maternal anti-HTLV-I-antibody titer (OR 2.2, p = 0.0013), a high maternal HTLV-I proviral load (OR 2.6, p = 0.033) and child's gender, girls being more frequently HTLV-I-infected than boys: OR 3.6, p = 0.0077 in the model including maternal anti-HTLV-I-antibody titer and OR 4.1, p = 0.002 in the model including the maternal HTLV-I proviral load.

Metabolite profiling study of propranolol in rat using LC/MS/MS analysis.

Metabolite profiling is one of the most challenging fields in applied mass spectrometry. Mass spectrometry was used to characterize the metabolites of propranolol, a beta-adrenergic receptor antagonist containing numerous oxidation sites. Propranolol is extensively metabolized, with most metabolites appearing in urine. Urine samples were collected from young adult male Sprague-Dawley rats. Structural identification of various metabolites was performed by LC/MS/MS, using a PE SCIEX triple quadrupole instrument (PE SCIEX API 3000). Metabolites were itemized using several LC/MS/MS techniques, including Q3 full scan and precursor and constant neutral loss experiments. A looped experiment technique revealed the presence of mono- and di-hydroxylated metabolites as well as regio isomers of hydroxy- and dihydroxy-propranolol glucuronides and propranolol glucuronic acid. Propranolol glucuronide was not observed, while the presence of dealkylated metabolites was suggested but not confirmed.

[Reemergence of yellow fever in West Africa: lessons from the past, advocacy for a control program]. / Réémergence de la fièvre jaune en Afrique de l'Ouest: leçons du passé, plaidoyer pour un programme de contrôle.

In French speaking West Africa, yellow fever vaccine became compulsory in 1941 for the entire African and European population. From 1941 to 1960, 146 million doses were distributed and the number of yellow fever cases declined sharply. No case was reported from 1954 to 1960. As a result of an interruption in systematic immunization after 1960, ten major epidemics broke out in West Africa between 1965 and 1995 (over 200,000 cases and 40,000 deaths). In 1967, the WHO programme for eradication of smallpox was initiated and it mobilized WHO's energy and finances. The expanded programme of immunization (EPI) was initiated in 1977 but it did not include the yellow fever vaccine. In 1978, Primary Health Care advocated an immunization strategy through fixed health facilities. In 1986, to amend this strategy, WHO recommended accelerating EPI progress and instituting National Immunization Days (NIDs). In 1990, a recommendation was made to include the yellow fever vaccine in the EPI. In 1997, the target of global poliomyelitis eradication by the year 2000 reinforced the NID programme and led to the use of mobile teams. At a time when a measles eradication programme is going to take over from the poliomyelitis programme, we must firmly advocate not omitting the yellow fever vaccine as was the case in 1977. Indeed, in yellow fever endemic areas, WHO recommends a simultaneous association of yellow fever and measles vaccines for nine month-old infants. This opportunity must be seized to initiate a yellow fever control programme.

Heparinase III limits rat arterial smooth muscle cell proliferation in vitro and in vivo.

Heparinase III degrades heparan sulfate proteoglycans, which are co-receptors for growth factors that stimulate arterial proliferation. We assessed the ability of locally-delivered heparinase III to limit medial vascular smooth muscle cell proliferation induced by balloon catheter injury in rat carotid arteries. Whereas vehicle-treated arteries showed 12% of smooth muscle cells proliferating after 2 days, heparinase III (0.022-5.7 mg/kg) treated arteries showed 0.8-4%. Chemically-inactivated heparinase III did not limit proliferation. In isolated rat A10 vascular smooth muscle cells, heparinase III (1 IU/ml) inhibited both PDGF-BB and bFGF mediated increases in proliferation and migration. These results suggest that heparinase III can limit proliferation by affecting heparan sulfate proteoglycan binding growth factors following arterial injury.

Demographic and familial characteristics of HTLV-1 infection among an isolated, highly endemic population of African origin in French Guiana.

To determine the epidemiological characteristics of human T cell leukemia/lymphoma virus type I (HTLV-I) infection in the endemic village of Maripasoula, French Guiana, 1,614 persons (83.2% of the population) aged 2 to 91 years (mean age 21) were studied from November 1994 through April 1995. Plasma samples were screened by an HTLV-I ELISA and an IFA test (on MT2 cells), and positive samples were tested by an HTLV-I and -II type-specific Western blot. Overall seropositivity in the village was 6.7%, but HTLV-I infection was restricted to 3 of 6 ethnic groups, including the Noir-Marron (descendants of escaped African slaves, 8%), the Creoles (4.1%) and those of mixed Noir Marron/other ethnicity (3.6%). In the Noir-Marron population of 1,222 persons, including 606 men and 616 women and representing 76% of those tested, HTLV-I seroprevalence increased significantly with age in both sexes, reaching 40% in women older than 50 years. Univariate risk factors for HTLV-I seropositivity in women included older age, more pregnancies, more live births and a history of hospitalization. A cross-sectional analysis of sexual partners demonstrated an excess of discordant female HTLV-I+/male HTLV-I- couples, indicating preferential male-to-female sexual transmission. The demonstration of II HTLV-I-seropositive children aged less than 15 years, of whom 9 had a seropositive mother, suggested maternal-child HTLV-I transmission. Our results demonstrate a very high seroprevalence of HTLV-I in this South American population descended from African slaves, probably due to high rates of mother-to-child and sexual transmission within this rather isolated group.

Goralatide (AcSDKP), a negative growth regulator, protects the stem cell compartment during chemotherapy, enhancing the myelopoietic response to GM-CSF.

The aim of our study was to investigate the protection afforded to the bone marrow by Goralatide (AcSDKP), an inhibitor of hemopoietic stem cell proliferation, when administered alone or in combination with a growth factor (granulocyte/macrophage colony-stimulating factor [GM-CSF]) during iterative cycles of Ara-C (cytarabine) treatment. In control mice receiving the inhibitor alone without Ara-C, the number of granulocytes was reduced during treatment, and a surge in number of peripheral blood cells was observed after its completion. Peripheral hematological responses were monitored during 3 consecutive cycles of Ara-C chemotherapy and the resultant nadir and recoveries. Analysis of variance of the treatment effects pooled over the 3 cycles showed that a treatment regimen in which the inhibitor was administered during the myelotoxic periods of chemotherapy confirmed the existence of a surge after completion of administration of the inhibitor and showed a significant protective effect. When the cycles of chemotherapy plus Goralatide were followed by GM-CSF, the recovery from leukopenic nadirs was accelerated and the white blood cells and granulocyte levels were markedly increased over those observed in control mice and in mice treated either with Goralatide alone or with GM-CSF alone. The differences were highly significant. A consistent and significant increase (p < 0.001) in platelet count was also noted in animals given Goralatide in conjunction with Ara-C or Ara-C + GM-CSF. After three treatment cycles, this response to the CSF was far better in mice treated by the inhibitor than when CSF was given alone, suggesting a protection of the stem cell pool.

HTLV-I infection in squirrel monkeys (Saïmiri sciureus) using autologous, homologous, or heterologous HTLV-I-transformed cell lines.

Peripheral blood mononuclear cells (PBMC) from three adult male squirrel monkeys (Saïmiri sciureus) were transformed by human T-cell leukemia/lymphoma virus type I (HTLV-I) by cocultivation with lethally irradiated human MT-2 cells. Three permanent monkey T-cell lines producing HTLV-I were obtained and characterized. Six weeks after inoculation seroconversion was observed in three of three monkeys inoculated with autologous transformed T cells and in two of three monkeys receiving homologous cells. Proviral DNA was detected in their PBMC at various times after inoculation, with the highest proviral load and antibody titers being found in monkeys infected with homologous cells. Monkeys inoculated with heterologous MT-2 cells did not seroconvert, and HTLV-I provirus was detected only transiently in their PBMC. To determine whether in vitro and in vivo HTLV-I infection of squirrel monkey cells led to a selection of monkey-adapted viral mutants, comparative sequencing of the proviral gp21 env between ex vivo monkey HTLV-I-infected PBMC, the inoculum, and MT-2 cells was done and no significant differences were detected. The squirrel monkey, which is naturally free of simian T-cell leukemia/ lymphoma virus, thus appears to be a suitable model for evaluating HTLV-I candidate vaccines and for studying the pathogenesis of HTLV-I.

Proliferative response of human and animal tumours to surgical wounding of normal tissues: onset, duration and inhibition.

Acceleration of secondary tumour growth and metastases following excision of a primary tumour has been attributed to the consequent removal of primary tumour-generated inhibitory factors. However, our studies have shown that surgical wounding of normal tissues significantly stimulated the growth of malignant tissues without the concomitant presence or excision of a tumour mass. A humoral stimulating component was indicated by the proliferative response of tumours and metastases distant from the surgical wound. All 16 human and murine tumours, of nine different histologies, showed a measurable acceleration of growth when implanted in surgically treated animals, suggesting that the ability of malignant tissue to respond to surgical wounding of normal tissue was not histologically or species specific. The proliferative surge of malignant tissues was detectable soon after wounding and had a duration of 2-3 days. The surgical wound as the source of the tumour-stimulating factor(s) was affirmed by the significant inhibition of tumour proliferative responses when a somatostatin analogue was applied topically to the surgical wound within 1 h of wounding, and/or during the critical tumour-stimulatory period of 1-2 days after wounding. A potential therapeutic window for reducing a risk factor that may be inadvertently imposed upon every surgical/oncology patient is indicated.

Clonal Variations and Virus Regulation by Aphids in Transmission of a French PAV-Type Isolate of Barley Yellow Dwarf Virus.

Twenty-one aphid clones of Rhopalosiphum padi and 21 clones of Sitobion avenae were evaluated for vector efficiency in transmitting a French PAV-type isolate (PAV-RG) of barley yellow dwarf virus (BYDV). All aphid clones transmitted the isolate, but vector efficiency was variable. The most efficient R. padi clone transmitted PAV-RG about twice as often as the least efficient one, Rp-CH (93 versus 38%). The most efficient S. avenae clone, however, transmitted PAV-RG eight times more often than the least efficient one, Sa-R5 (76 versus 8%). All aphid clones acquired virus as determined by triple antibody sandwich-enzyme-linked immunosorbent assay (TAS-ELISA), but the amount of virus acquired differed among the clones. After a 5-day inoculation access period on healthy plants, virus titer in some aphid clones was not detectable by TAS-ELISA in samples of 10 aphids, but immunocapture-polymerase chain reaction (IC-PCR) could detect the virus in the extract of single aphids of all the clones. In most cases, a rapid reduction of PAV-RG titer in the aphids was associated with lower transmission efficiency. In a serial transmission test of 11 days, clonal variations in vector efficiency were consistently observed. After a 5-day transfer, vector efficiency of the six clones tested declined. Vector efficiency was significantly correlated with the level of virus titer in the aphids. Following the serial transfer, decline of virus titer in feeding aphids was triphasic, with an initial decrease occurring rapidly after the first transfer, then decreasing slowly. A second rapid reduction in virus titer often occurred after 7 days of transfer. In the serial transmission test, all three R. padi clones tested transmitted and retained virus until the last transfer at 11 days. The Sa-Chat1 and Sa-V clones of S. avenae successively transmitted and retained PAV-RG for 11 and 9 days, respectively. The Sa-R5 clone transmitted PAV-RG until the 9-day transfer, but retained the virus for 11 days. Thus, the clonal variations in vector efficiency were not ascribed to poor ability to acquire the virus, but were associated with a possible transmission barrier of virions, as well as a more rapid reduction of virus titer in aphids.