Microsatellite typing reveals strong genetic structure of Schistosoma mansoni from localities in Kenya.

Genetic diversity and population structure of seven populations of Schistosoma mansoni sampled in Kenya were assessed using five microsatellite markers. The mean number of alleles per locus, expected heterozygosity in Hardy-Weinberg equilibrium and pairwise F(ST) values ranged from 5.2 to 10.7, 0.5-0.8 and 3.6-27.3%, respectively. These data reveal that S. mansoni populations in Kenyan have relatively high levels of genetic diversity and is significantly differentiated. Our data combined with information on biogeography support the hypothesis that the strong genetic structure in Kenyan schistosomes is as a result of limited gene flow and large population sizes. Resistance to anthelminthics has not been reported among the Kenyan schistosomes, we hypothesize that this is probably due to the very little gene flow among populations, thereby limiting opportunities for the spread of rare alleles that might confer resistance to the drugs.

A neotropical snail host of Schistosoma mansoni introduced into Africa and consequences for the schistosomiasis transmission Biomphalaria tenagophila in Kinshasa (Democratic Republic of Congo).

Malacological surveys carried out in the early 1970s in water bodies of the Kinshasa area, Lower Zaire (Democratic Republic of Congo), showed the appearance of a Biomphalaria species which was identified as Biomphalaria camerunensis. In 1976, other surveys confirmed the presence of the species in several sites and showed numerous infected snails with Schistosoma mansoni, demonstrating for the first time an active transmission of the parasite responsible of the intestinal schistosomiasis in this area. The most recent malacological sampling was carried out by one of us in 1994 in Mangungu River and revealed the presence of apparently the same snail species. However, conchological, anatomical and molecular studies showed that this snail may be considered as an introduced neotropical species, B. tenagophila. To our knowledge, this is the second example of the introduction of a neotropical snail host of schistosomes into Africa.

Phylogeography of Biomphalaria glabrata and B. pfeifferi, important intermediate hosts of Schistosoma mansoni in the New and Old World tropics.

The historical phylogeography of the two most important intermediate host species of the human blood fluke Schistosoma mansoni, B. glabrata in the New World, and B. pfeifferi in the Old World, was investigated using partial 16S and ND1 sequences from the mitochondrial genome. Nuclear sequences of an actin intron and internal transcribed spacer (ITS)-1 were also obtained, but they were uninformative for the relationships among populations. Phylogenetic analyses based on mtDNA revealed six well-differentiated clades within B. glabrata: the Greater Antilles, Venezuela and the Lesser Antilles, and four geographically overlapping Brazilian clades. Application of a Biomphalaria-specific mutation rate gives an estimate of the early Pleistocene for their divergence. The Brazilian clades were inferred to be the result of fragmentation, due possibly to climate oscillations, with subsequent range expansion producing the overlapping ranges. Within the Venezuela and Lesser Antilles clade, lineages from each of these areas were estimated to have separated approximately 740 000 years ago. Compared to B. glabrata, mitochondrial sequences of B. pfeifferi are about 4x lower in diversity, reflecting a much younger age for the species, with the most recent common ancestor of all haplotypes estimated to have existed 880 000 years ago. The oldest B. pfeifferi haplotypes occurred in southern Africa, suggesting it may have been a refugium during dry periods. A recent range expansion was inferred for eastern Africa less than 100 000 years ago. Several putative species and subspecies, B. arabica, B. gaudi, B. rhodesiensis and B. stanleyi, are shown to be undifferentiated from other B. pfeifferi populations.

A potential snail host of schistosomiasis in Bolivia: Biomphalaria amazonica Paraense, 1966.

Biomphalaria amazonica Paraense, 1996 was collected from a permanent pond in the outskirts of the Bolivian city of Santa Cruz. Identification of the collected specimens was made by comparison with the original description of the species and with topotypic material in the collection of Instituto Oswaldo Cruz. Phylogenetic analysis confirmed that these Bolivian specimens belong to B. amazonica.

A potential snail host of schistosomiasis in Bolivia: Biomphalaria amazonica Paraense, 1966

Biomphalaria amazonica Paraense, 1996 was collected from a permanent pond in the outskirts of the Bolivian city of Santa Cruz. Identification of the collected specimens was made by comparison with the original description of the species and with topotypic material in the collection of Instituto Oswaldo Cruz. Phylogenetic analysis confirmed that these Bolivian specimens belong to B. amazonica

Evolutionary relationships and biogeography of Biomphalaria (Gastropoda: Planorbidae) with implications regarding its role as host of the human bloodfluke, Schistosoma mansoni.

The wide geographic distribution of Schistosoma mansoni, a digenetic trematode and parasite of humans, is determined by the occurrence of its intermediate hosts, freshwater snails of the genus Biomphalaria (Preston 1910). We present phylogenetic analyses of 23 species of Biomphalaria, 16 Neotropical and seven African, including the most important schistosome hosts, using partial mitochondrial ribosomal 16S and complete nuclear ribosomal ITS1 and ITS2 nucleotide sequences. A dramatically better resolution was obtained by combining the data sets as opposed to analyzing each separately, indicating that there is additive congruent signal in each data set. Neotropical species are basal, and all African species are derived, suggesting an American origin for the genus. We confirm that a proto-Biomphalaria glabrata gave rise to all African species through a trans-Atlantic colonization of Africa. In addition, genetic distances among African species are smaller compared with those among Neotropical species, indicating a more recent origin. There are two species-rich clades, one African with B. glabrata as its base, and the other Neotropical. Within the African clade, a wide-ranging tropical savannah species, B. pfeifferi, and a Nilotic species complex, have both colonized Rift Valley lakes and produced endemic lacustrine forms. Within the Neotropical clade, two newly acquired natural hosts for S. mansoni (B. straminea and B. tenagophila) are not the closest relatives of each other, suggesting two separate acquisition events. Basal to these two species-rich clades are several Neotropical lineages with large genetic distances between them, indicating multiple lineages within the genus. Interesting patterns occur regarding schistosome susceptibility: (1) the most susceptible hosts belong to a single clade, comprising B. glabrata and the African species, (2) several susceptible Neotropical species are sister groups to apparently refractory species, and (3) some basal lineages are susceptible. These patterns suggest the existence of both inherent susceptibility and resistance, but also underscore the ability of S. mansoni to adapt to and acquire previously unsusceptible species as hosts. Biomphalaria schrammi appears to be distantly related to other Biomphalaria as well as to Helisoma, and may represent a separate or intermediate lineage.

A phase I trial of CV706, a replication-competent, PSA selective oncolytic adenovirus, for the treatment of locally recurrent prostate cancer following radiation therapy.

CV706 is a prostate-specific antigen (PSA)-selective, replication-competent adenovirus that has been shown to selectively kill human prostate cancer xenografts in preclinical models. To study the safety and activity of intraprostatic delivery of CV706, a Phase I dose-ranging study for the treatment of patients with locally recurrent prostate cancer after radiation therapy was conducted. Twenty patients in five groups were treated with between 1 x 10(11) and 1 x 10(13) viral particles delivered by a real-time, transrectal ultrasound-guided transperineal technique using a three-dimensional plan. The primary end point was the determination of treatment-related toxicity. Secondary objectives included evaluation of the antitumor activity of CV706 and monitoring for other correlates of antineoplastic action. In this study, CV706 was found to be safe and was not associated with irreversible grade 3 or any grade 4 toxicity. No grade >1 alterations in liver function tests associated with CV706 administration were observed. Posttreatment prostatic biopsies and detection of a delayed "peak" of circulating copies of virus provided evidence of intraprostatic replication of CV706. The study defined the timing of CV706 shedding into blood and urine as well as the appearance of circulating Ad5 neutralizing antibodies. Finally, this study documents the serum PSA response of treated patients and reveals a dose response showing that all five patients who achieved a > or =50% reduction in PSA were treated with the highest two doses of CV706. This study represents the first clinical translation of a prostate-specific, replication-restricted adenovirus for the treatment of prostate cancer. Taken together, this study documents that intraprostatic delivery of CV706 can be safely administered to patients, even at high doses, and the data also suggest that CV706 possesses enough clinical activity, as reflected by changes in serum PSA, to warrant additional clinical and laboratory investigation.

Hematozoa of hatch-year common mergansers from Michigan.

Fifty-five hatch-year common mergansers (Mergus merganser) were sampled for hematozoa from Douglas Lake (Michigan, USA) on 17 July 1995. Forty-one (75%) were infected with hematozoa. Haemoproteus greineri and Leucocytozoon simondi were common, infecting 28 (51%) and 26 (47%) common mergansers, respectively. Plasmodium circumflexum infected two (4%) birds. The common merganser is a new host record for H. greineri and P. circumflexum. Intensity data indicate possible negative interspecific interaction between H. greineri and L. simondi.

Schistosoma mansoni and Biomphalaria: past history and future trends.

Schistosoma mansoni is one of the most abundant infectious agents of humankind. Its widespread distribution is permitted by the broad geographic range of susceptible species of the freshwater snail genus Biomphalaria that serve as obligatory hosts for its larval stages. Molecular phylogenetic studies suggest that Schistosoma originated in Asia, and that a pulmonate-transmitted progenitor colonized Africa and gave rise to both terminal-spined and lateral-spined egg species groups, the latter containing S. mansoni. Schistosoma mansoni likely appeared only after the trans-Atlantic dispersal of Biomphalaria from the Neotropics to Africa, an event that, based on the present African fossil record, occurred only 2-5 million years ago. This parasite became abundant in tropical Africa and then entered the New World with the slave trade. It prospered in the Neotropics because a remarkably susceptible and productive host, B. glabrata, was widely distributed there. Indeed, a snail similar to B. glabrata may have given rise to the African species of Biomphalaria. Schistosoma mansoni has since spread into other Neotropical Biomphalaria species and mammalian hosts. The distribution of S. mansoni is in a state of flux. In Egypt, S. mansoni has nearly completely replaced S. haematobium in the Nile Delta, and has spread to other regions of the country. A susceptible host snail, B. straminea, has been introduced into Asia and there is evidence of S. mansoni transmission in Nepal. Dam and barrage construction has lead to an epidemic of S. mansoni in Senegal, and the parasite continues its spread in Brazil. Because of competition with introduced aquatic species and environmental changes, B. glabrata and consequently S. mansoni have become less abundant on the Caribbean islands. Control of S. mansoni using praziquantel and oxamniquine has reduced global prevalence but control is difficult to sustain, and S. mansoni can develop tolerance/resistance to praziquantel, raising concerns about its future efficacy. Because of legitimate environmental concerns, snail control is unlikely to be an option in future control efforts. Global warming will impact the distribution of Biomphalaria and S. mansoni, but the magnitude and nature of the effects are poorly understood.

Analysis of messages expressed by Echinostoma paraensei miracidia and sporocysts, obtained by random EST sequencing.

A lambdaZAP Express cDNA library was constructed with mRNA obtained from immature miracidia within eggs, hatched miracidia, and sporocysts of Echinostoma paraensei. This cDNA library was amplified and 213 expressed sequence tag (EST) sequences (averaging 466 nucleotides in length) were obtained. The mean percentage of unresolved bases within the EST sequences was 0.4%, ranging from 0 to 4.6%. The 213 ESTs represent 151 unique messages. BLAST (version 2.0.8) analysis disclosed that 64 unique E. paraensei messages (42.4%) had significant similarities (BLAST score < or =e-5), at deduced amino acid or nucleotide levels, with known sequences in the nonredundant GenBank databases or the dbEST database (NCBI). The remainder, 57.6% of the unique EST-encoded messages, scored nonsignificant hits. Most of the E. paraensei messages that could be assigned a cellular role based on sequence similarities were involved in gene/protein expression. Several ESTs scored highest similarities with sequences obtained from trematode species. A total of 22,560 nucleotides present in open reading frames from ESTs that aligned with known sequences was used to determine codon usage for E. paraensei. Analysis of a subset of eight ESTs that contained full-length open reading frames did not reveal a bias in codon usage. Also, EST sequences were found to contain 3' untranslated regions with an average length of 69.9 +/- 88.4 nucleotides (n = 46). The EST sequences were submitted to GenBank/dbEST, adding to the 51 available Echinostoma-derived sequences, to provide reference information for both phylogenetic analysis and study of general trematode biology.

Safety of tacrine: clinical trials, treatment IND, and postmarketing experience.

The safety of tacrine (Cognex), a centrally active, reversible acetylcholinesterase inhibitor approved in 1993 for the treatment of mild to moderate dementia of the Alzheimer type, was evaluated in 2,706 patients with Alzheimer disease (AD) in clinical trials and in 9861 patients with AD in a treatment investigational new drug (TIND) program. More than 190,000 patients in the United States received tacrine during the first 2 years following marketing approval. The most common tacrine-associated adverse events were elevated liver transaminase levels [alanine aminotransferase (ALT) and, to a lesser degree, aspartate aminotransferase] and peripheral cholinergic events involving primarily the digestive system (nausea, vomiting, diarrhea, dyspepsia, anorexia, and weight loss). Based on clinical trial experience, potentially clinically significant (>3 x upper limit of normal) ALT elevations occurred in 25% of patients, requiring routine monitoring early in treatment. The elevations were almost always asymptomatic, rarely accompanied by significant increases in bilirubin, and related to time on drug rather than to dose (90% occurred within the first 12 weeks of treatment). Gastrointestinal events were related to dose and generally of mild to moderate intensity. Tacrine-associated events, including ALT elevations, were reversible. Cholinergic events were manageable with dosage adjustment. Tacrine was not associated with permanent liver injury in clinical trials or a TIND setting.

In vivo regulation of CrkII and CrkL proto-oncogenes in the uterus by insulin-like growth factor-I. Differential effects on tyrosine phosphorylation and association with paxillin.

Changes in CrkII and CrkL phosphorylation are associated with insulin-like growth factor receptor activation in cultured cells. We examined whether similar changes also occur following administration of recombinant human insulin-like growth factor-I to the intact animal. In female rats starved overnight, CrkL phosphorylation was significantly increased 12 min after insulin-like growth factor-I administration. Tyrosine phosphorylation of CrkII was not detectable in either control or treated animals. Paxillin, a 65-70-kDa phosphoprotein containing high affinity binding sites common for the Src homology 2 (SH2) domains of CrkII and CrkL, was observed in both CrkII and CrkL immunoprecipitates. Insulin-like growth factor-I treatment stimulated the association of CrkII with paxillin. In contrast, the same treatment resulted in the dissociation of the CrkL-paxillin complex. Similar effects of insulin-like growth factor-I treatment on the association of CrkL with tyrosine phosphorylated paxillin were observed in fibroblasts overexpressing CrkL. This study demonstrates that the activation of the insulin-like growth factor-I receptor induces changes in the tyrosine phosphorylation and protein-protein interactions of the Crk proteins in vivo. The different responses of CrkL and CrkII to insulin-like growth factor-I receptor activation suggest distinct roles for these two adapter proteins in signal transduction.

Parasites of the deepwater sculpin, Myoxocephalus thompsoni (Cottidae), from Lake Michigan and Lake Huron.

A total of 190 deepwater sculpins, Myoxocephalus thompsoni, collected in 1995 from Michigan waters of Lake Michigan and Lake Huron was examined for parasites. Five parasite species occurred in sculpins from Lake Michigan with Echinorhynchus salmonis being most common. Six parasite species infected sculpins from Lake Huron, with Haplonema sp. the most common. Haplonema sp. is the only gravid helminth species reported from deepwater sculpins. Pleistophora sp. and Trichodina sp. infected sculpins from Lake Huron and Lake Michigan. Parasite species richness for sculpins at the 3 locations ranged from 5 to 6; mean values ranged from 1.18 to 1.39 for examined fish. The restricted diet of deepwater sculpin, which may be related to the depth of its habitat, appears to determine its helminth fauna. Deepwater sculpin may be an important transport host for E. salmonis, Cyathocephalus truncatus, and Eubothrium salvelini to lake trout and burbot that commonly feed on them.

Somatostatin-receptor imaging of medullary thyroid carcinoma.

In-111 pentetreotide scintigraphy of 10 patients with residual or metastatic medullary thyroid carcinoma is described. Six patients had sporadic tumor and 4 had MEN IIB. Foci of increased tracer uptake were observed in 9 patients: in the thyroid bed (4 patients), the mediastinum (3 patients.), the shoulder area and left lower abdomen (1 patient), and the left upper abdomen (1 patient). The 10th patient had no abnormal uptake. CT confirmed 2 mediastinal lesions and 2 out of 3 thyroid masses, but did not detect the thyroid remnants or the lesions in the shoulder area and abdomen. Lung lesions < or = 1 cm in diameter and ill-defined liver foci (2 patients) were seen on CT, but not on scintigraphy. Small liver metastases not demonstrated on CT or on scintigraphy were identified at surgery in a MEN IIB patient. Elevated urinary epinephrine was found in 2 out of 4 MEN IIB patients. In one, tracer uptake in the left adrenal corresponded to a mass on CT, to pathological uptake of MIBG and DMSA, and to a tumor removed at surgery. The second patient had peritoneal spread of malignant pheochromocytoma (at surgery), but negative CT and only a single focus in the left lower abdomen on scintigraphy. Somatostatin-receptor imaging is useful for the detection of residual and recurrent medullary thyroid carcinoma, and may identify pheochromocytoma in MEN IIB patients.