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Biomedical subjects

R E Davis

Publications and source records attributed to R E Davis.

At least 145 records · Page 8Linked to original sources
PubMed1991

Inflammatory pseudotumor of lymph nodes. Additional observations and evidence for an inflammatory etiology.

Inflammatory pseudotumor of lymph nodes (IPT), a recently described benign cause of lymphadenopathy, was studied in 14 patients using paraffin-section immunohistochemistry. All biopsies showed a proliferation of spindle cells (small blood vessels, histiocytes, and "activated" fibroblasts resembling myofibroblasts) containing a mixture of inflammatory cells without atypia and involving the connective tissue framework (hilum and sinuses) of the lymph node. Ten patients had additional histologic features of IPT originally described (extranodal extension, obliterative vasculitis, and endothelial infiltration), and nine of these had associated fever of unknown origin, which in some was relieved by biopsy alone. Additional features observed focally in some cases but not previously described included lymph node parenchymal infarction, fibrinoid vascular necrosis, karyorrhexis, and involvement of only part of the lymph node. Immunostaining showed the lymphoid infiltrate to be predominantly of T-lineage (except for plasma cells), only a minority of which marked as T-helper cells. Numerous mononuclear cells resembling histiocytes were identified, some of which had a spindled shape but reacted with an antibody (KP1) of myelomonocytic specificity. Large fibroblastic cells expressed alpha-muscle actin but not desmin, similar to myofibroblasts in granulation tissue. The morphologic and immunohistologic features were similar to those in inflammatory pseudotumors of spleens and livers also studied, but the lack of simultaneous lymph node involvement argued against a common etiology. The findings suggest that the mass lesion of IPT is produced in response to localized lymph node inflammation or injury and further exclude hematolymphoid or mesenchymal neoplasia as a cause.

Adolescent↗
PubMed1991

An NMDA intervention strategy in schizophrenia with "low-dose" milacemide.

Drugs (e.g., PCP) which interfere with glutamatergic transmission at the N-methyl D-aspartate (NMDA) subclass of glutamate receptors precipitate both positive and negative symptoms of psychosis in humans. Based on a proposed "glutamatergic deficiency" in schizophrenia, pharmacologic facilitation of NMDA-mediated neural transmission by direct stimulation of the strychine-insensitive glycine binding site was attempted with "low-dose" milacemide, an acylated "prodrug" of glycine that readily crosses the blood brain barrier and is converted into glycine in the brain. In a prior study, "high-dose" milacemide proved to have no therapeutic utility in schizophrenia. The failure was thought, possibly, to be related to higher doses of milacemide having antagonist actions at the NMDA receptor complex. In the current study, "low-dose" milacemide (400 mg/day), as the sole pharmacotherapeutic agent, was also without significant clinical benefit. Despite our negative findings for milacemide, other strategies for facilitating NMDA-mediated neural transmission in schizophrenia might be worth pursuing.

Acetamides↗
PubMed1991

Genetic Interrelatedness among Clover Proliferation Mycoplasmalike Organisms (MLOs) and Other MLOs Investigated by Nucleic Acid Hybridization and Restriction Fragment Length Polymorphism Analyses.

DNA was isolated from clover proliferation (CP) mycoplasmalike organism (MLO)-diseased periwinkle plants (Catharanthus roseus (L.) G. Don.) and cloned into pSP6 plasmid vectors. CP MLO-specific recombinant DNA clones were biotin labeled and used as probes in dot hybridization and restriction fragment length polymorphism analyses to study the genetic interrelatedness among CP MLO and other MLOs, including potato witches'-broom (PWB) MLO. Results from dot hybridization analyses indicated that both a Maryland strain of aster yellows and a California strain of aster yellows are distantly related to CP MLO. Elm yellows, paulownia witches'-broom, peanut witches'-broom, loofah witches'-broom, and sweet potato witches'-broom may be very distantly related, if at all, to CP MLO. A new Jersey strain of aster yellows MLO, tomato big bud MLO, clover phyllody MLO, beet leafhopper-transmitted virescence MLO, and ash yellows MLO are related to CP MLO, but PWB MLO is the most closely related. Similarity coefficients derived from restriction fragment length polymorphism analyses revealed that PWB and CP MLOs are closely related strains and thus provided direct evidence of their relatedness in contrast to reliance solely on biological characterization.

Journal Article↗
PubMed1991

Three-dimensional high-resolution volume rendering (HRVR) of computed tomography data: applications to otolaryngology-head and neck surgery.

Conventional computed tomographic display formats are not optimal for demonstrating three-dimensional anatomic relationships. In otolaryngology--head and neck surgery these critical relationships are often highly complex, and their complete understanding is essential to a successful surgical outcome. A new computer-generated image display format, high-resolution volume rendering (HRVR), facilities the understanding of these critical anatomic relationships by transforming conventional imaging data into clinically relevant 3-D images. Unlike many other 3-D reconstruction algorithms, HRVR suffers minimal data loss in the conversion process, which in turn provides for superior image resolution. This better allows the application of 3-D technology to small or complicated anatomic structures such as those frequently encountered in otolaryngology--head and neck surgery. Advances in computer-controlled manipulations that further enhance the evaluation of desired pathologic features have been achieved. This pilot study contains representative clinical cases chosen to illustrate the potential utility of HRVR in otolaryngology--head and neck surgery. The authors believe HRVR images will enhance the surgeon's understanding of the 3-D anatomic relationships that exist between critical pathologic features and surrounding vital structures.

Aged↗
PubMed1991

Growth fraction estimation of malignant lymphomas in formalin-fixed paraffin-embedded tissue using anti-PCNA/Cyclin 19A2. Correlation with Ki-67 labeling.

The immunohistochemical detection of PCNA/Cyclin, a nuclear protein associated with cell proliferation, represents a potentially useful tool for the study of tumor proliferative activity. Previous studies investigating the reactivity of anti-PCNA/Cyclin monoclonal antibody 19A2 have not clearly defined the population of proliferating cells with which 19A2 reacts in tissue sections. The authors describe a method for detection of PCNA/Cyclin in formalin-fixed, paraffin-embedded tissue using a routine biotin-streptavidin immunohistochemical system that employs an anti-IgM, mu-chain-specific second-stage antibody. The authors used this method to study the proliferative activity of 24 malignant lymphomas, consisting of 12 low-grade lymphomas (LGLs) and 12 intermediate-grade lymphomas (IGLs), and five reactive tonsils. 19A2 data was compared with Ki-67 labeling in frozen sections in the same group of cases. 19A2 provided easily detectable nuclear staining of proliferating cells with reactive cells demonstrating varying intensity of staining, this latter finding most likely due to the varying nuclear concentration of PCNA/Cyclin protein during the cell cycle. In tonsils, 19A2 reacted with germinal center cells and basal keratinocytes. In the malignant lymphomas, there was good correlation between 19A2 and Ki-67 data (r = 0.90, P less than 0.001). The subgroup of LGLs showed a mean PCNA/Cyclin of 26% and a mean Ki-67 of 28%. In the subgroup of IGLs, mean PCNA/Cyclin = 54% and mean Ki-67 = 59%. These results indicate that 19A2 detects a fraction of proliferating cells that is similar to that detected by Ki-67, ie, the growth fraction, and that 19A2 is a reliable marker of proliferative activity in uniformly handled, formalin-fixed, paraffin-embedded tissue.

Antibodies↗
PubMed1991

Streptavidin-biotin immunotoxins: a new approach to purging bone marrow.

Immunotoxins have been used both experimentally and clinically to purge bone marrow of tumor cells or T cells before transplantation. We describe the synthesis of a streptavidin-biotin-toxin conjugate using whole ricin. Streptavidin-biotin-ricin (SA-BR) conjugates were synthesized by biotinylation of whole ricin, which was then complexed with streptavidin. Hybrid molecules consisting of a single biotinylated ricin moiety linked to a streptavidin molecule were separated by gel filtration. This SA-BR conjugate was used in an indirect cytotoxicity assay. The assay involved sensitizing of target cells with biotinylated monoclonal antibody (B-MCAB) followed by treatment with dilutions of SA-BR conjugate. The assay demonstrated a specific antibody-directed cytotoxicity. The strength of this SA-BR system is that a single conjugate was able to be used in conjunction with a library of B-MCABs to selectively target phenotypically different cell types. The application of the SA-BR conjugate is thus only restricted by the availability of B-MCABs specific for the desired target cells. The high affinity of avidin for biotin (Kd approximately 10(-15)) and the ability of a single conjugate to target phenotypically different cells through utilization of a library of B-MCABs gives SA-BR conjugates great potential in the selective targeting of individual cell types.

Antibodies, Monoclonal↗
PubMed1991

Inflammatory pseudotumor of intra-abdominal lymph nodes manifesting as recurrent fever of unknown origin: a case report.

A 27-year-old man presented with a 7-month history of debilitating recurrent fever and weight loss. Extensive clinical evaluation led to the discovery of splenomegaly and retroperitoneal lymphadenopathy. The patient underwent splenectomy as well as liver and lymph node biopsy. Histologic examination of the lymph nodes, but not the liver and spleen, revealed inflammatory pseudotumor of lymph nodes. The patient has remained asymptomatic for more than 3 years following the surgical procedure despite the absence of further intervention. Inflammatory pseudotumor of lymph nodes should be considered in the differential evaluation of prolonged or relapsing fever of unknown etiology.

Abdominal Neoplasms↗
PubMed1990

Effect of optic nerve lesions and intraocular colchicine on cell proliferation in the germinal zone of the optic tectum and in the torus longitudinalis in the goldfish.

Postembryonic development of the optic tectum occurs in part through proliferation of cells in the germinal zone located at the caudal edges of each lobe. Autoradiography experiments by others have shown that [3H]thymidine labeling in the germinal zone is decreased following optic nerve crush or enucleation and restored above normal levels during optic nerve regeneration. The present autoradiography experiments examined the relationship between retinal innervation and the rate of mitotic activity in the tectum germinal zone and in the torus longitudinalis. The fish received optic nerve crush to temporarily deafferent the tectum, enucleation for permanent deafferentation, or an intraocular injection of 0.01-1.0 microgram of colchicine to reversibly inhibit axonal transport in the optic nerve. Thymidine labeling in the tectum germinal zone showed that nerve crush resulted in decreased mitotic activity in most fish within 6 days followed by recovery by 21 days; enucleation decreased mitotic activity more uniformly and for more than 42 days with recovery by 84 days postaxotomy; colchicine produced a dose-dependent inhibition of mitotic activity which was reversed by 42 days postinjection. Axonal transport was restored by 42 days postinjection. In the torus longitudinalis, nerve crush produced a brief increase in mitotic activity followed by a return to normal; enucleation and colchicine resulted in a lasting decrease in mitotic activity and atrophy indicating a loss of cells or neuropil. The data are consistent with the proposal that cell proliferation in the tectum germinal zone is stimulated by the accretion of fibers from developing retinal ganglion cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Endoscopic comparison of cimetidine and sucralfate for prevention of naproxen-induced acute gastroduodenal injury. Effect of scoring method.

Nonsteroidal antiinflammatory drug-induced gastroduodenal mucosal damage observed endoscopically is usually categorized as hemorrhages, erosions, or ulcerations. We undertook this study to determine whether the injury produced by a commonly prescribed NSAID, naproxen, could be reduced by cotherapy with sucralfate or cimetidine and to determine how dependent the differences in the degree of protection against mucosal injury measured were on the scoring system used. Four groups of 20 healthy volunteers with endoscopically normal gastric and duodenal mucosa received naproxen (500 mg twice a day) plus cimetidine (300 mg four times a day or 400 mg twice a day), sucralfate (1 g four times a day), or placebo for seven days. After seven days of therapy, a second endoscopy was performed. Separate scoring systems were used for the presence of hemorrhages, erosions, and a combination of both types of injury. There were significantly fewer mucosal hemorrhages present when naproxen and cimetidine were administered than when naproxen was administered with placebo or sucralfate (placebo vs 300 mg cimetidine, P = 0.04, and placebo vs 400 mg cimetidine, P = 0.006, placebo vs sucralfate, P = 0.26). Both cimetidine dosages resulted in significantly fewer hemorrhages than were present following cotherapy of naproxen and sucralfate (P less than 0.05). In contrast, there was no discernible difference in the mucosal injury between placebo and any drug or between any two active therapies when the injury was evaluated based on the presence of gastric erosions.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

Primary large-cell lymphoma of the thymus: a diffuse B-cell neoplasm presenting as primary mediastinal lymphoma.

Primary mediastinal nonlymphoblastic non-Hodgkin's lymphoma (NLNHL) has distinct clinical, histologic (diffuse large-cell morphology, often with sclerosis and clear cytoplasm), and immunohistochemical features (predominantly B-cell lineage, usually immunoglobulin-negative), which suggest origin from a unique B-cell population. The thymus has a resident population of B cells with a unique immunophenotype, and can be involved by primary mediastinal NLNHL, in some cases selectively. Fifteen cases of NLNHL involving the thymus were studied by paraffin-section immunohistochemistry using antibodies to formalin-resistant epitopes of B cells (4KB5 [CD45RA] and L26 [CD20]) and T cells (L60 [CD43] and UCHL1 [CD45RO]). All were diffuse large-cell or immunoblastic lymphomas with sclerosis, and were also similar to primary mediastinal NLNHL in clinical features. Neoplastic cells stained with L26 in all but one case, which stained with 4KB5 and an antibody to a leukocyte-common antigen (PD7/26 [CD45RB]), and were uniformly nonreactive with L60 (with one exception) and UCHL1. Intermingled small lymphocytes were uniformly L26-negative and positive for T-cell markers, even in one case with atypia suggesting a lymphoma of mixed morphology. These findings demonstrate that primary thymic and primary mediastinal NLNHL are similar B-lineage neoplasms, and support previous suggestions that both may originate in thymic B cells.

Adolescent↗
PubMed1990

A spliced leader is present on a subset of mRNAs from the human parasite Schistosoma mansoni.

We present evidence that a subset of mRNAs in the human parasitic trematode Schistosoma mansoni contain an identical 36-nucleotide spliced leader (SL) sequence at their 5' termini. The SL is derived from a 90-nucleotide nonpolyadenylylated RNA (SL RNA), presumably by trans-splicing. Neither the SL nor the SL RNA share significant sequence identity with previously described trans-spliced leaders and SL RNAs in trypanosomatid protozoans or nematodes. However, several features, such as predicted secondary structure, trimethylguanosine cap, and potential Sm binding site, suggest similarities among SL RNAs in widely divergent organisms. Our evidence also indicates that the exon 3 acceptor site of the 3-hydroxy-3-methylglutaryl-CoA reductase gene can be spliced either to the SL by trans-splicing or to an upstream exon, 2, by cis-splicing. The presence of a SL sequence in S. mansoni, a member of the phylum Platyhelminthes, suggests that transplicing may be a common feature of other lower invertebrates.

Animals↗
PubMed1990

Nonradioactive screening method for isolation of disease-specific probes to diagnose plant diseases caused by mycoplasmalike organisms.

DNA fragments of tomato big bud (BB) mycoplasmalike organism (MLO) in diseased periwinkle plants (Catharanthus roseus L.) were cloned to pSP6 plasmid vectors and amplified in Escherichia coli JM83. A nonradioactive method was developed and used to screen for MLO-specific recombinants. Cloned DNA probes were prepared by nick translation of the MLO recombinant plasmids by using biotinylated nucleotides. The probes all hybridized with nucleic acid from BB MLO-infected, but not healthy, plants. Results from dot hybridization analyses indicated that several MLOs, e.g., those of Italian tomato big bud, periwinkle little leaf, and clover phyllody, are closely related to BB MLO. The Maryland strain of aster yellows and maize bushy stunt MLOs are also related to BB MLO. Among the remaining MLOs used in this study, Vinca virescence and elm yellows MLOs may be very distantly related, if at all, to BB MLO. Potato witches' broom, clover proliferation, ash yellows, western X, and Canada X MLOs are distantly related to BB MLO. Southern hybridization analyses revealed that BB MLO contains extrachromosomal DNA that shares sequence homologies with extrachromosomal DNAs from aster yellows and periwinkle little leaf MLOs.

Journal Article↗
PubMed1990

Definition of the complete Schistosoma mansoni hemoglobinase mRNA sequence and gene expression in developing parasites.

Schistosoma mansoni uses a variety of proteases termed hemoglobinases to obtain nutrition from host globin. Previous reports have characterized cDNAs encoding 1 of these enzymes. However, these sequences did not define the primary structures of the mRNA and protein. The complete sequence of the 1390 base mRNA has now been determined. It encodes a 50 kDa primary translation product. In vitro translations coupled with immunoprecipitations and Western blots of parasite lysates allowed visualization of the 50 kDa form. Production of the 31 kDa mature hemoglobinase from the 50 kDa species involves removal of both NH2 and COOH terminal residues from the primary translation product. Expression of hemoglobinase mRNA and protein was examined during larval parasite development. Low levels were observed in young schistosomula. After 6-9 days in culture, high hemoglobinase levels were seen which correlated with the onset of red blood cell feeding. Immunoelectron microscopy was employed to examine hemoglobinase location and function. In adult worms the enzyme was associated with the gut lumen and gut epithelium. In cercariae, the protease was observed in the head gland, suggesting new roles for the protease.

Amino Acid Sequence↗
PubMed1990

Joint service training for medical readiness.

Medical Readiness Training is of major importance in preparing to meet the challenge of medical care during wartime and national emergencies or disasters. As an alternative to simulated casualty training, the U.S. Public Health Service and the U.S. Army joined forces to provide "real world" medical care for troops during training. Although simulated training provides insight into casualty and trauma medicine, it is felt that many aspects of real medical care are often ignored or taken for granted. Providing medical care under austere field conditions provides a realistic environment and presents situations that can not be evaluated by simulated training.

Disaster Planning↗
PubMed1989

Alcohol intakes and deficiencies in thiamine and vitamin B6 in black patients with cardiac failure.

Thiamine and vitamin B6 status was evaluated in 73 consecutive black patients with cardiac failure at Baragwanath Hospital. They consumed moderate to large amounts of traditional as well as Western-type beer and liquor. Thirty per cent had erythrocyte thiamine concentrations below the reference range. The transketolase response to thiamine pyrophosphate (TPP effect) suggested thiamine deficiency in 32.4%, of whom 13.2% were classified as severely deficient. Vitamin B6 deficiency was present in 21.4%, with a further 42.9% in the very low normal range. Only one patient had beriberi heart disease. Idiopathic dilated cardiomyopathy was the main cause of cardiac failure. It is suggested that excessive alcohol consumption is an important factor contributing to cardiac morbidity in urban blacks.

Adult↗