Frank F. Richards's research while affiliated with Massachusetts General Hospital and other places

Publications (92)

Article
The African trypanosomes bear on the outside of their cell membrane a single 10–15 nm thick coat of a glycoprotein. This glycoprotein may differ in structure in the predominant populations of parasitemic waves found in relapsing infections. Variant Specific Glycoprotein (VSG) range in MW between 53,000–63,000 d and may have variable amounts of carb...
Article
A short-term cell culture is used to propagate and purify rat-derived Pneumocystis carinii (Pc). An aliquot of pelleted material washed out of the lungs of rats with moderate to severe Pc pneumonia is cultured for 7 to 10 days on the adherent mink lung cell line Mv 1 Lu, and the rest of the material is frozen down in medium with 10% glycerol. Altho...
Article
Pneumocystis carinii is an opportunistic pathogen of man, carried as a commensal in healthy subjects. It frequently causes a fatal pneumonia in the immunosuppressed host. It is a major complication of HIV-1 infection in man (AIDS). Using surface radioiodination of rat-derived P. carinii trophozoites obtained from in vitro culture, a major surface g...
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The alveolar macrophage (AM) oxidative burst response is an important component of microbicidal effector cell function against a variety of potential pathogens in the lungs, although the role against Pneumocystis carinii has not been fully investigated. The goals of this study were to characterize the P. carinii-mediated oxidative burst of AMs from...
Article
Paratransgenesis, a strategy for control of certain arthropod-borne infectious diseases, involves expression of disease transmission-blocking molecules by genetically altered symbiotic bacteria of insect vectors. Field use of this approach relies on a method for dispersal of genetically transformed bacteria to their host insects. Rhodococcus rhodni...
Article
Expression within insects of foreign antiparasitic gene products via microbial symbionts could be used to prevent transmission of vector-borne pathogens to vertebrate hosts. Genetically transformed symbiotic bacteria Rhodococcus rhodnii expressed functional antibody fragments (rDB3 encoding murine V(H)/K which binds progesterone) that were exported...
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Bacterial symbionts may be used as vehicles for expressing foreign genes in arthropods. Expression of selected genes can render an arthropod incapable of transmitting a second microorganism that is pathogenic for humans and is an alternative approach to the control of arthropod-borne diseases. We discuss the rationale for this alternative approach,...
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The macrophage mannose receptor, a pattern recognition molecule and component of innate immunity, mediates binding and phagocytosis of Pneumocystis carinii and likely represents an important clearance mechanism in the lungs of immunocompetent hosts. The purpose of this study was to examine the ability of alveolar macrophages from HIV-infected indiv...
Article
Bacterial symbionts may be used as vehicles for expressing foreign genes in arthropods. Expression of selected genes can render an arthropod incapable of transmitting a second microorganism that is pathogenic for humans and is an alternative approach to the control of arthropod-borne diseases. We discuss the rationale for this alternative approach,...
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Surfactant protein-A (SP-A) levels are increased in Pneumocystis carinii pneumonia, but the role of SP-A in the pathogenesis of P. carinii pneumonia is not completely understood. This study investigated the effect of SP-A on the in vitro binding and phagocytosis of P. carinii by normal human alveolar macrophages (AM). Determination of binding and p...
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Little is known about the molecules involved in the regulation of Pneumocystis carinii replication and development in vitro and in vivo. We describe in this report the identification of a P. carinii gene encoding the P. carinii prohibitin protein. In mammals, the prohibitin gene product has been shown to negatively regulate cell proliferation. A cD...
Article
Full-text available
Expression of molecules with antiparasitic activity by genetically transformed symbiotic bacteria of disease-transmitting insects may serve as a powerful approach to control certain arthropod-borne diseases. The endosymbiont of the Chagas disease vector, Rhodnius prolixus, has been transformed to express cecropin A, a peptide lethal to the parasite...
Article
An initial and crucial step in the establishment of many microbial infections is the attachment of the pathogen to the host cells. Thus, adherence of Pneumocystis carinii (Pc) to type I pneumocytes is believed to be important in the induction of Pc pneumonia. Little is known about the nature of the attachment of Pc to type I cells, although extrace...
Article
Some of the world's most devastating diseases are transmitted by arthropod vectors. Attempts to control these arthropods are currently being challenged by the widespread appearance of insecticide resistance. It is therefore desirable to develop alternative strategies to complement existing methods of vector control. In this review, Charles Beard, S...
Article
Two isolates of bacterial endosymbionts, GP01 and GM02, were established in cell free medium from haemolymph of the tsetse, Glossina pallidipes and G. morsitans. These microorganisms appear similar to rickettsia-like organisms reported previously from various tsetse species. The 16S rRNA sequence analysis, however, placed them within the gamma subd...
Article
The spliced leader RNA(SL RNA)-encoding genes of the salivarian New World trypanosome, Trypanosoma rangeli, are organized within the 5S rRNA tandem repeats. Each repeat contains genes encoding an SL RNA and a 5S rRNA in the same orientation of transcription. This SL-5S organization is also present in the African trypanosome, Trypanosoma vivax. A si...
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During skin penetration, infective hookworm larvae encounter hyaluronic acid as they migrate between epidermal keratinocytes and through the ground substance of the dermis. A hyaluronidase would facilitate passage through the epidermis and dermis during larval invasion. Zoonotic hookworm larvae of the genus Ancylostoma were shown to contain a hyalu...
Article
Full-text available
A shuttle plasmid was developed that is capable of replicating both in Escherichia coli and in Rhodococcus rhodnii, a bacterial symbiont of the Chagas' disease vector Rhodnius prolixus. We have been able to transform R. rhodnii with this plasmid, infect aposymbiotic R. prolixus with the transformed symbionts, select with the antibiotic thiostrepton...
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A new member of a family of site-specific retrotransposons is described in the New World trypanosome Trypanosoma cruzi. This element, CZAR (cruzi-associated retrotransposon), resembles two previously described retrotransposons found in the African trypanosome T. brucei gambiense and the mosquito trypanosomatid Crithidia fasciculata in specifically...
Article
A new member of a family of site-specific retrotransposons is described in the New World trypanosome Trypanosoma cruzi. This element, CZAR (cruzi-associated retrotransposon), resembles two previously described retrotransposons found in the African trypanosome T. brucei gambiense and the mosquito trypanosomatid Crithidia fasciculata in specifically...
Article
Groups of barrier-raised but not certified virus-free Sprague-Dawley rats, obtained from the same source over the course of several years, were placed on an identical immunosuppressive regimen. This caused reactivation of latent Pneumocystis carinii infection, manifest as P. carinii pneumonia (PCP) of varying severity. Rats were euthanized after 9-...
Article
Growth of P. carinii in culture has been difficult to document in the absence of reliable methods for distinguishing live from dead organisms. We studied three markers of cell function in P. carinii during the course of short-term cell culture, and correlated these with the number of P. carinii present in culture supernatants. The markers were gluc...
Article
Understanding the pathophysiology of Pneumocystis carinii infection has been limited by the availability of methods for precisely measuring the interaction of P. carinii with host cells. Here we describe a new method which allows for the rapid assessment of P. carinii binding to, and internalization by, adherent alveolar macrophages. The method is...
Article
In African trypanosomes the requirements for glucose and its metabolism vary in different stages of the life cycle. Here we present evidence that cultured procyclic trypanosomes of Trypanosoma brucei rhodesiense uptake glucose against a concentration gradient in a time and dose-dependent manner. Moreover, glucose transport is completely inhibited b...
Article
Rat-derived Pneumocystis carinii lysed with sodium deoxycholate catalysed the incorporation of uridine diphosphoglucose into an insoluble polymer. This enzyme activity was present in both the pellet and the supernatant when the P. carinii preparations were centrifuged. The polymer whose production was catalysed by the supernatant was examined by ma...
Article
Human exposure to Pneumocystis carinii is common but, in the absence of acquired or genetic dysfunction of either cellular or humoral immunity, exposure rarely leads to illness. Although alveolar macrophages can degrade P. carinii, macrophage receptors involved in P. carinii recognition have not been clearly defined. Characterization of a predomina...
Article
We have characterized a retrotransposon in Trypanosoma brucei gambiense uniquely associated with the spliced-leader (SL) RNA gene cluster (Spliced Leader Associated Conserved Sequence, SLACS). There are nine copies of SLACS and DNA sequence analysis of one shows the hallmarks of Line-1 like elements. SLACS has generated a 49 bp target DNA duplicati...
Article
An apparatus is described that allows for the filter paper culture of third-stage hookworm larvae, suitable for biochemical studies. The method used consumes less time and space than conventional Harada-Mori test tube cultures, allowing for the application of a large volume of feces over a surface area of up to 6,400 cm² within a box small enough f...
Article
Full-text available
Radioiodination of rat-derived Pneumocystis carinii obtained from an in vitro culture demonstrated the presence of a major surface glycoprotein (gp120). The glycoprotein was of the high mannose type. It exhibited adherence properties similar to those observed in the intact organism. Under nonreducing conditions, it existed as an aggregate with a mo...
Article
A short-term cell culture is used to propagate and purify rat-derived Pneumocystis carinii (Pc). An aliquot of pelleted material washed out of the lungs of rats with moderate to severe Pc pneumonia is cultured for 7 to 10 days on the adherent mink lung cell line Mv 1 Lu, and the rest of the material is frozen down in medium with 10% glycerol. Altho...
Article
Full-text available
The 140-nucleotide spliced leader (SL) RNA, involved in mRNA maturation in the African trypanosomes and in other kinetoplastida, is encoded by a tandem array of spliced leader genes. We show that the 1.4-kb SL gene repeat unit in Trypanosoma gambiense is organized in tandem arrays confined to two large (minimum size 350-450 kb) restriction fragment...
Article
Full-text available
We have isolated the gene coding for the U2 analogue in trypanosomes. The 148 nucleotide long U2 RNA is capped and transcribed from a single copy gene. The 5′ half of the molecule is highly homologous to mammalian U2 RNA, while the 3′ half does not show any significant sequence homology with the mammalian counterpart. Nevertheless, the trypanosome...
Article
Full-text available
In Trypanosoma brucei gambiense, the Ca2+ binding protein calmodulin is encoded by three identical tandemly repeated genes. The transcripts of these genes consist of several RNA species similar in size. A 35-nucleotide spliced leader sequence is present at the 5' end of each mRNA but is not encoded by DNA contiguous to these genes. We have identifi...
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Infection with the African trypanosomes gives rise to relapsing waves of parasitemia in the host. A predominant population of trypanosomes is present in each wave, and such predominant populations are usually serologically distinct from each other. Trypanosomes are covered by an extramembranous, highly antigenic, variant-specific glycoprotein coat...
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African trypanosomes change their antigenicity by successively expressing different members of a group of related but highly diverse proteins, the variant surface glycoproteins (VSGs). We describe a synthetic oligonucleotide that can prime specifically reverse transcription of VSG mRNA out of total trypanosome poly(A)+ RNA. The specificity of this...
Article
Anti-GM4 antiserum was prepared from rabbits by immunization with pure human brain GM4 ganglioside in complete Freund's adjuvant and methylated bovine serum albumin. None of the immunized animals developed any clinically apparent neurological dysfunction. The antiserum titer and specificity were analyzed by double immunodiffusion and a novel solid-...
Article
Tubulointerstitial nephritis was produced in 19 of 23 New Zealand White rabbits challenged i.v. with adjuvant-free homologous urine for greater than or equal to 16 wk and 11 of 14 challenged with adjuvant-free rabbit Tamm-Horsfall protein for 2 to 24 wk. Lesions were identical in the two groups of rabbits and were characterized by focal mononuclear...
Article
A radioimmunoassay (RIA) for the variant-specific glycoproteins (VSG-1 and VSG-2) of two sequentially appearing variants of Trypanosoma congolense has been devised. When the isoelectrically focused VSG-1 components (VSG-1a, VSG-1b, and VSG-1c) are used as inhibitors of the VSG-1-anti-VSG-1 interaction, the RIA inhibition curves resemble each other,...
Article
Two sequential variant-specific glycoproteins have been purified from two variants of Trypanosoma congolense expressed during a relapsing infection. Isolation of the two glycoproteins, termed VSG-1 and VSG-2, respectively, employed glycerol lysis followed by purification on concanavalin A, Sephadex G-25, and gradient-eluted DE-52 columns. Partially...
Article
A strain of Trypanosoma congolense has been cloned, passaged through the tsetse fly, and subsequently recloned. Relapsing infections have been induced in two rats by syringe passage of the cloned trypanosomes. The variant-specific glycoprotein of the initial cloned variant (VSG-1) and those from the two different variants produced in the two relaps...
Article
Two Trypanosoma congolense variant-specific glycoproteins, which are expressed sequentially during a relapsing infection, have been purified. The proteins, termed VSG-1 and VSG-2, both have a molecular weight of 53,000 as determined by SDS polyacrylamide electrophoresis. When either antigen is electrophoresed through a pH gradient on an isoelectric...
Article
Previous work has shown that (BALB/c x A)F, (CAF1) mice with an immunological disorder, the graft-versus-host reaction (GVHR), express an oncogenic murine leukemia virus (MuLV) which appears to be responsible for the subsequent development of lymphoreticular tumors. A mink cell focus-inducing (MCF) virus has been isolated from a reticulum cell neop...
Article
As a model for human lung cancer, squamous cell carcinomas were induced by 3-methylcholanthrene in mouse tracheas which had been explanted to a subcutaneous site. The tumors that developed were examined for both ecotropic and xenotropic infectious murine leukemia virus (MuLV). From all squamous carcinomas--six out of six--a xenotropic MuLV was isol...
Article
Sera directed against the public and private idiotypic determinants of protein 460 and protein 315 were used to detect the presence of these idiotypic markers in serum immunoglobulins of various inbred mouse strains. Private protein 315 determinants were not detected in any of the mouse strains tested. Presence of protein 460 private idiotype was c...
Article
The preparation and characterization of rabbit antibodies directed against structures associated with thehapten binding site of proteins 315 and 460 is described. That these antibodies are site-directed was shown by: (a) specific elution of anti-idiotypes by hapten; (b) the inability of these rabbit antibodies to bind to affinity labeled proteins 3...
Article
Both myeloma protein 460 and myeloma protein 315 each exhibit two sets of idiotypic determinants. A ‘private’ determinant set which distinguishes protein 460 and protein 315 from each other, and a common or ‘public’ set of idiotypic determinants which are shared by proteins 315 and 460 and which distinguish these two proteins from many other mouse...
Article
Yields of Trypanosoma congolense grown in rats may be increased by placing the rats in a 37 °C environment for 1 hr prior to sacrifice. A further increase in the number of parasites recovered per rat may be achieved by replacement of blood removed by a lactated Ringer's solution with 5% glucose as the rat is being bled from the abdominal aorta. The...
Chapter
When a mammalian organism is immunized with an antigenic determinant, a highly complex humoral immune response is induced. This consists of a large number of antibodies complementary to the antigenic determinant. Such antibodies may vary in class and subclass. Furthermore, within a single subclass, there are differences in the energy of interaction...
Article
Urinary tract obstruction and vesicoureteral reflux, which are often associated with urinary tract infections, may lead to progressive renal damage. Relatively little is known about the pathophysiology of this process, and a need exists for noninvasive methods of its detection in its early stages. Because urine is refluxed into the venous and lymph...
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Full-text available
Plasmacytomas are induced in BALB/c mice by the intraperitoneal injection of pristane (2,6,10,14-tetra-methylpentadecane) after a latent period of six months and more [Anderson, P. N. & Potter, M. (1969) Nature 222, 994-995]. Spleen cells mesenteric lymph node cells, thoracic lymph node cells, and peritoneal exudate cells were prepared from pristan...
Article
A patient with abdominal pain, weight loss, and a gastric mass was found to have a pleomorphic infiltrate of lymphocytes and plasma cells. Analysis of serum proteins revealed gamma heavy chains, which were detected in the urine as well. This case is unusual because of the extralymphatic involvement and the possibly unique character of the heavy cha...
Chapter
An immune serum usually consists of a very heterogeneous population of immunoglobulins (Ig’s) the appearance of which in the serum has been induced by antigen. The antigen-ligating function of the Ig molecule (see Figure 1) is confined to the combining regions, which are two symmetrical areas at the solvent-exposed ends of the Fab arms of the Y-sha...
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Full-text available
Mice of the low leukemia (BALB/cJ x A/J)F1 hybrid (CAF1) strain express B-and N-tropic infectious murine leukemia virus (MuLV) after the age of 6 mo. Initation of a protracted immunological disorder, the graft-versus-host reaction (GVHR), at 7 wk of age, accelerates the induction of both these mouse-tropic endogenous viruses, and preferentially enh...
Article
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When mice are sequentially immunized with two antigens to give an oligoclonal "double-binding" antibody response, there is a concomitant increase of "double-binding" cell surface receptors on their splenic lymphocytes. Competition studies suggest that the capacity to bind the two ligands, bovine pancreatic ribonuclease (EC 3.1.4.22) and a 2,4-dinit...
Article
Affinity labels have been used in an attempt to identify amino acid residues in and around the binding sites for protein ligands, substrates, and inhibitors. They have also been used to identify proteins with particular binding specificities when the protein is part of a more complicated organelle, such as a membrane or ribosome. An ideal affinity...
Article
Cellfree extracts (CFEs) prepared from (BALB/cJ X A/J)F1 (CAF1) and (BALB/cJ X C57BL/6J)F1 (CB6F1) mice in which a graft-versus-host reaction (GVHR) has been induced are known to be oncogenic, but only after a protracted latent period (mean, 16 mo). Serial passage of such CFEs in successive generations of syngeneic mice inoculated at birth led to t...
Article
Protein 460 is a mouse γA2 myeloma immunoglobulin which binds competitively two haptens, ϵ-2,4 dinitrophenyl lysine and Menadione thioglycollate at the immunoglobulin combining region. In close relation to this combining region, protein 460 contains a heavy chain cysteine residue which has been substituted with 2 fluorescent donor probes. We have m...
Article
Proteins 315 and 460 are IgA2 mouse myeloma immunoglobulins which bind the haptens 2,4-Dnp and Menadione, and their derivatives competitively in the combining region. We have studied the binding of these proteins to a series of Dnp and Menadione based solid phase immunoabsorbents with different length spacer groups to which the Dnp and Menadione gr...
Article
Proteins 315 and 460 are IgA2 mouse myeloma immunoglobulins which bind the haptens 2,4-Dnp and Menadione, and their derivatives competitively in the combining region. We have studied the binding of these proteins to a series of Dnp and Menadione based solid phase immunoabsorbents with different length spacer groups to which the Dnp and Menadione gr...
Article
Full-text available
Murine lymphoid cells were infected in vitro with WN 1802 B, a naturally occurring murine leukemia virus isolated from the spleen of an 18-month-old BALB/c mouse. Normal spleen and bone marrow cells were more susceptible to infection than were cells prepared from thymus and lymph node. Spleen cells from athymic nu/nu mice also could be readily infe...
Article
It seems likely that immunoglobulins have evolved from some archetypal molecule and those forms which are useful to the animal have been retained. It is this entire population of antibodies which forms the humoral immune system and in such a system, not only the properties of individual antibody combining regions, but the properties of the multipro...
Article
The arrangement of interchain disulfide bonds in immunoglobulins may be determined in a single experiment by two-dimensional SDS-polyacrylamide-gel electrophoresis. The noncovalently associated subunits are first separated on a cylindrical acrylamide-gel by electrophoresis under dissociating conditions. The subunits are then subjected to reduction...
Article
The amino acid residues of the mouse γA immunoglobulin protein 460 modified with two photoaffinity reagents, 2,4-dinitrophenylalanyl diazoketone and 2,4-dinitro-1-azobenzene, are compared with the labeling pattern produced by bromoacetyl-based dinitrophenyl affinity labels. Both the diazoketone reagent and the bromoacetyl reagent N-bromoacetyl-N′-2...
Article
A mouse IgA myeloma protein, protein 460, which binds the 2,4-dinitrophenyl (Dnp) group was reacted with two photoaffinity labeling reagents, Dnp-alanyl diazoketone (which we have previously shown to label residue 54 in the light chain) and Dnp-N3. The residues that react with Dnp-N3 are located in two separate fragments derived from the heavy-chai...
Article
IgG New binds ligands such as orceine, menadione, and uridine with a low affinity (K0 about 1 × 10³ liter/mol) and a γ-hydroxy derivative of vitamin K1 with a higher affinity (K0 = 1.7 × 10⁵ liter/mol). Binding studies indicate that both the 2-methylnaphthoquinone rings and the phytyl tail of the vitamin K1 hapten contribute to the total binding en...
Article
A rapid method for screening myeloma immunoglobulins for binding activity is described, based on the principle that low energy interactions between immunoglobulins and haptens are relatively frequent and may be used as indicator systems for finding other interactions of higher energy. Amino groups on partially hydrolyzed nylon screen discs are used...