Biomedical subjects
H Kaplan
Publications and source records attributed to H Kaplan.
The epidemiology of infectious diseases among South American Indians: a call for guidelines for ethical research.
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Noninvasive localization of tumors by immunofluorescence imaging using a single chain Fv fragment of a human monoclonal antibody with broad cancer specificity.
BACKGROUND: A single chain antibody fragment, NovoMAb-G2-scFv, derived from a human anti-tumor monoclonal antibody recognizes tumor antigen molecules expressed on a wide variety of human cancers including melanoma, breast carcinoma, colon adenocarcinoma, squamous cell carcinoma, lung carcinoma, and prostate carcinoma. This study was designed to evaluate the use of a NovoMab-G2-scFv/cyanine fluorochrome (Cy5.5.18) conjugate as diagnostic tool for in vivo imaging of tumors. METHODS: The NovoMab-G2-scFv-Cy5 complex was administered to athymic mice injected subcutaneously with human melanoma tumor cells, and the distribution of fluorescence was imaged noninvasively using a charge-coupled device camera. Images were acquired 2, 6, 12, 24, 48, and 72 hours after injection. RESULTS: Fluorescence was detected at the tumor site after injection of NovoMab-G2-scFv-Cy5 but not after injection of a labeled irrelevant control antibody fragment. Fluorescence from the tumor site peaked 2 hours after injection and gradually declined, reaching a minimum 72 hours after injection. Fluorescence was also apparent in the kidneys, indicating clearance of the complex through the kidneys. Results suggest that 16% and 73% of the antibody is located in the tumor and kidneys, respectively. Imaging of isolated organs confirmed the presence of the NovoMab-G2-scFv-Cy5 complex in tumors, kidneys, and liver. No fluorescence was observed in other organs. CONCLUSIONS: Specific binding of the antibody-dye complex to the tumor was observed, and the kinetics of binding to tumors and kidneys were determined. These results suggest that the NovoMab-G2-scFv-Cy5.5 complex may be used for noninvasive tumor localization.
Dynamics and three-dimensional localization of ribosomal RNA within the nucleolus.
Although rRNA synthesis, maturation, and assembly into preribosomal particles occur within the nucleolus, the route taken by pre-rRNAs from their synthetic sites toward the cytoplasm remains largely unexplored. Here, we employed a nondestructive method for the incorporation of BrUTP into the RNA of living cells. By using pulse-chase experiments, three-dimensional image reconstructions of confocal optical sections, and electron microscopy analysis of ultrathin sections, we were able to describe topological and spatial dynamics of rRNAs within the nucleolus. We identified the precise location and the volumic organization of four typical subdomains, in which rRNAs are successively moving towards the nucleolar periphery during their synthesis and processing steps. The incorporation of BrUTP takes place simultaneously within several tiny spheres, centered on the fibrillar centers. Then, the structures containing the newly synthesized RNAs enlarge and appear as compact ringlets disposed around the fibrillar centers. Later, they form hollow spheres surrounding the latter components and begin to fuse together. Finally, these structures widen and form large rings reaching the limits of the nucleoli. These results clearly show that the transport of pre-rRNAs within the nucleolus does not occur randomly, but appears as a radial flow starting from the fibrillar centers that form concentric rings, which finally fuse together as they progress toward the nucleolar periphery.
Use of the pH memory effect in lyophilized proteins to achieve preferential methylation of alpha-amino groups.
It is demonstrated that the pH memory effect can be used to control the ionization state of amino groups in lyophilized proteins and hence their chemical reactivity toward modifying reagents. When proteins were lyophilized from aqueous solutions at pH values between 6 and 7 and reacted in vacuo with iodomethane, the alpha-amino groups were found to be either preferentially or selectively trimethylated. Reaction with 13C-labeled iodomethane permitted detection and identification of individual trimethylated alpha-amino groups by 13C-NMR spectroscopy as distinct peaks in the spectral region between 52 and 57 ppm. There was adequate sensitivity to detect minor resonances of free alpha-amino groups arising from proteolysis of the major protein or from protein impurities. The resonances of the trimethylated alpha-amino groups in standard amino acids and peptides are sufficiently close to those in the derivatized protein to make a tentative identification of the N-terminal amino acid. It is also demonstrated that advantage can be taken of the pH memory effect to use the preferential 13C-methylation of amino groups to verify whether a protein has a free or blocked amino terminus.
Chronic axillary hidradenitis--the efficacy of wide excision and flap coverage.
A number of different modalities of surgical treatment for axillary hidradenitis suppurativa have been suggested. This study compares three different methods of surgical excision. Fifty-nine patients (94 axillae) were treated over a 14-year period. There were 42 females and 17 males with an average age of 32 years (range 16-65 years). Twenty-six axillae had excision of only the diseased skin and recurrent disease occurred in seven. However, in 39 axillae that were treated by excision of all the hair bearing skin, only three developed recurrent disease, which is a significant reduction in the incidence of recurrent disease (P = 0.04, Fischer's exact test). Twenty-nine axillae were treated by wide local excision (2 cm beyond the hair bearing skin) and no recurrence occurred. However, there was no statistical difference (P = 0.18, Fischer's exact test) in disease recurrence between excision of all the hair bearing skin and wide local excision. This study suggests that excision of all the hair bearing skin is the preferred method of surgical treatment. Flap coverage was an effective method to achieve wound closure after adequate excision and can be achieved by random fasciocutaneous flaps for small or medium sized defects and parascapular flaps for large defects.
Fermentation of fructooligosaccharides by lactic acid bacteria and bifidobacteria.
Lactic acid bacteria and bifidobacteria were screened of their ability to ferment fructooligosaccharides (FOS) on MRS agar. Of 28 strains of lactic acid bacteria and bifidobacteria examined, 12 of 16 Lactobacillus strains and 7 of 8 Bifidobacterium strains fermented FOS. Only strains that gave a positive reaction by the agar method reached high cell densities in broth containing FOS.
The changing faces of optometry.
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A proactive approach.
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Airway epithelial cell migration dynamics. MMP-9 role in cell-extracellular matrix remodeling.
Cell spreading and migration associated with the expression of the 92-kD gelatinase (matrix metalloproteinase 9 or MMP-9) are important mechanisms involved in the repair of the respiratory epithelium. We investigated the location of MMP-9 and its potential role in migrating human bronchial epithelial cells (HBEC). In vivo and in vitro, MMP-9 accumulated in migrating HBEC located at the leading edge of a wound and MMP-9 expression paralleled cell migration speed. MMP-9 accumulated through an actin-dependent pathway in the advancing lamellipodia of migrating cells and was subsequently found active in the extracellular matrix (ECM). Lamellipodia became anchored through primordial contacts established with type IV collagen. MMP-9 became amassed behind collagen IV where there were fewer cell-ECM contacts. Both collagen IV and MMP-9 were involved in cell migration because when cell-collagen IV interaction was blocked, cells spread slightly but did not migrate; and when MMP-9 activation was prevented, cells remained fixed on primordial contacts and did not advance at all. These observations suggest that MMP-9 controls the migration of repairing HBEC by remodeling the provisional ECM implicated in primordial contacts.
Life history traits in humans: theory and empiricial studies.
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Role of DNA in the activation of the Cry1A insecticidal crystal protein from Bacillus thuringiensis.
The Cry1A insecticidal crystal protein (protoxin) from six subspecies of Bacillus thuringiensis as well as the Cry1Aa, Cry1Ab, and Cry1Ac proteins cloned in Escherichia coli was found to contain 20-kilobase pair DNA. Only the N-terminal toxic moiety of the protoxin was found to interact with the DNA. Analysis of the crystal gave approximately 3 base pairs of DNA per molecule of protoxin, indicating that only a small region of the N-terminal toxic moiety interacts with the DNA. It is proposed that the DNA-protoxin complex is virus-like in structure with a central DNA core surrounded by protein interacting with the DNA with the peripheral ends of the C-terminal region extending outward. It is shown that this structure accounts for the unusual proteolysis observed in the generation of toxin in which it appears that peptides are removed by obligatory sequential cleavages starting from the C terminus of the protoxin. Activation of the protoxin by spruce budworm (Choristoneura fumiferana) gut juice is shown to proceed through intermediates consisting of protein-DNA complexes. Larval trypsin initially converts the 20-kilobase pair DNA-protoxin complex to a 20-kilobase pair DNA-toxin complex, which is subsequently converted to a 100-base pair DNA-toxin complex by a gut nuclease and ultimately to the DNA-free toxin.
Agrobacterium-transformed rice plants expressing synthetic cryIA(b) and cryIA(c) genes are highly toxic to striped stem borer and yellow stem borer.
Over 2,600 transgenic rice plants in nine strains were regenerated from >500 independently selected hygromycin-resistant calli after Agrobacterium-mediated transformation. The plants were transformed with fully modified (plant codon optimized) versions of two synthetic cryIA(b) and cryIA(c) coding sequences from Bacillus thuringiensis as well as the hph and gus genes, coding for hygromycin phosphotransferase and beta-glucuronidase, respectively. These sequences were placed under control of the maize ubiquitin promoter, the CaMV35S promoter, and the Brassica Bp10 gene promoter to achieve high and tissue-specific expression of the lepidopteran-specific delta-endotoxins. The integration, expression, and inheritance of these genes were demonstrated in R0 and R1 generations by Southern, Northern, and Western analyses and by other techniques. Accumulation of high levels (up to 3% of soluble proteins) of CryIA(b) and CryIA(c) proteins was detected in R0 plants. Bioassays with R1 transgenic plants indicated that the transgenic plants were highly toxic to two major rice insect pests, striped stem borer (Chilo suppressalis) and yellow stem borer (Scirpophaga incertulas), with mortalities of 97-100% within 5 days after infestation, thus offering a potential for effective insect resistance in transgenic rice plants.
Report of eight cases of humeral fracture following the throwing of hand grenades.
A series of eight cases is presented in which similar fractures of the shaft of the humerus occurred during the throwing of hand grenades. Transient paresis of the radial nerve accompanied the fracture in one patient. In seven patients, the fracture healed without complication. In the remaining case, non-union developed, and surgical treatment was instituted. The mechanism of the fracture is discussed with reference to the literature.
Utilization of rheumatology physician services by the elderly.
PURPOSE: To examine rheumatology subspecialty practice patterns, determinants of referral to rheumatologists, and utilization of aspiration and injection procedures in a population-based sample of elderly individuals. SUBJECTS AND METHODS: We obtained Medicare physician claims for all visits to rheumatologists among beneficiaries aged 65 years and older in Colorado, Massachusetts, and Virginia in 1993, and for visits to all providers by patients with coded diagnoses of rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). We examined variations in visit frequency and aspiration/injection procedures, and we analyzed determinants of referral to a rheumatologist for RA or SLE. RESULTS: In 1 year, 144,797 visits were made to rheumatologists by 38,443 patients in the three states. An inflammatory disorder was coded in 45% of visits and a noninflammatory disorder in 50%. Half of patients with RA were seen three or fewer times in the year. For RA and SLE, African Americans were about 60% as likely to be seen by a rheumatologist as whites. Utilization of rheumatologist services for rheumatoid arthritis and systemic lupus erythematosus was highest in the state (Virginia) with the lowest per capita supply of rheumatologists. Among patients with bursitis, tendinitis, and osteoarthritis, African-American women were more likely to receive an injection or aspiration procedure than whites or African-American men. CONCLUSION: Elderly patients with rheumatologic disorders were seen by specialists less frequently than recommended by a recent rheumatology manpower survey. African-Americans with RA and SLE had fewer rheumatology visits than whites.
Syndromes of thrombosis and hypercoagulability. Congenital and acquired causes of thrombosis.
Blood coagulation protein and platelet defects are now known to account for up to ninety percent of unexplained venous thrombosis and up to seventy percent of unexplained arterial thrombotic or ischemic events. This article summarizes the common and uncommon blood protein and platelet defects which should be suspected, and searched for, in patients with such events. Defining such defects will have major impact on secondary prevention and duration of antithrombotic therapy in the afflicted patient and impact on primary prevention for identified family members in those harboring hereditary defects.
Impact of extreme donor age on the outcome of living-related donor kidney transplantation.
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Spruce budworm elastase precipitates Bacillus thuringiensis delta-endotoxin by specifically recognizing the C-terminal region.
A gut juice protein from Choristoneura fumiferana (spruce budworm) larvae that precipitates certain delta-endotoxins shows a unique specificity for the C-terminal amino acid sequence. Using homolog scanning mutants, we have identified a contiguous region of the Cry1Aa toxin which interacts with the 75-kDa toxin precipitating protein (TPP-75)' resulting in precipitation. The contiguous region from Cry1Aa can be transferred to Cry1Ac and results in an identical precipitation reaction. The precipitation reaction occurs rapidly and is unique in that the ratio of precipitating protein to toxin is low (estimated at 0.01), unlike antibody-antigen reactions which exhibit mole ratios close to 1. TPP-75 has been characterized as an elastase-like serine protease. We have taken advantage of this serine protease character and incorporated a radiolabel using an irreversible inhibitor. The radiolabel has allowed us to show the coincidence of the catalytically-inhibited TPP-75 with the toxin in a blotting assay and to follow the degradation of TPP-75 during storage. TPP-75 represents the first evidence that gut juice proteins may selectively attenuate the activity of delta-endotoxins, prior to binding to putative receptors on susceptible cells. TPP-75 should be evaluated as a possible resistance mechanism for those larvae that do not exhibit a receptor-based resistance.