Biomedical subjects
J G Smith
Publications and source records attributed to J G Smith.
Vasculitis.
Many cutaneous and systemic disorders are associated with inflammation and necrosis of blood vessels. Several classifications of vasculitis have been used. Internists tend to utilize the classification of Fauci with modifications such as those by Cupps. Gibson and Ryan, who are dermatopathologists, have classified vasculitis based on vessel size, leukocyte type, and presence of granulomas. A more recent classification has been developed by Jennette, a pathologist, and colleagues. The etiology of vasculitis is varied; it includes bacteria, viruses, chemicals, autoimmune disease, malignancy and abnormal exogenous and endogenous proteins. Leukocytoclastic vasculitis can be experimentally reproduced by the Arthus phenomenon. IgM and C3 are found in cutaneous blood vessels and associated with circulating immune complexes. CH50, C3 and C4 may be reduced in serum. Increased incidence of nasal carriage of staphylococci is associated with higher relapse rates in Wegener's granulomatosis and toxic shock syndrome toxin from staphylococci is associated with the Kawasaki syndrome. Additionally, at least four systemic vasculitic drug reactions can be confirmed with patch testing. Antineutrophil cytoplasmic antibodies (ANCA) are found in association with certain systemic vasculitides. These may be tested with indirect immunofluorescence and enzyme linked immunosorbent assays (ELISA) with radioimmunoassays. Originally cytoplasmic ANCA (cANCA) was identified with proteinase 3 as the antigen and perinuclear ANCA (pANCA) was related to myeloperoxidase. While cANCA is very specific for proteinase 3, pANCA is associated with a number of antigens other than myeloperoxidase. pANCA is found with alcohol fixed but not formalin-fixed neutrophils. cANCA is particularly sensitive and specific for Wegener's granulomatosis and predicts prognosis and response to therapy. pANCA is not so specific and is associated with a number of other vasculitic syndromes. Cutaneous vasculitis is managed primarily with colchicine, dapsone and prednisone, with recent studies indicating that there may be a synergistic effect of pentoxifylline with dapsone. Systemic vasculitis involves treatment with various agents. Recently it has been observed that co-trimoxazole (trimethoprim/sulfamethoxazole) is useful in many cases of Wegener's granulomatosis along with other more toxic chemotherapeutic agents.
Netherton's syndrome.
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The effect of haemopoietic growth factors on the cell cycle of AML progenitors and their sensitivity to cytosine arabinoside in vitro.
This study examines the effect of pretreatment in liquid culture of acute myeloid leukaemic (AML) progenitors with recombinant human IL-3 or G and GM-CSF. Prior to and following cytokine priming, the sensitivity of cells to cytosine arabinoside (Ara-C) at concentrations ranging from 10(-12) to 10(-4) M was assessed in clonogenic culture. In addition, the initial percentage of AML cells in S phase was assessed and their subsequent kinetic response to cytokine treatment evaluated by FACScan analysis. Light-density marrow cells (LDMCs) from 19 AML patients were initially T-cell and monocyte depleted in order to remove potential sources of endogenous cytokine production prior to in vitro investigation. LDMCs were incubated in liquid phase for 7 d in a chemically defined complete medium with or without cytokines. Clonogenic data from fresh AML LDMCs not pretreated with growth factors demonstrated a heterogenous response to Ara-C. In only 4/15 marrows tested clonogenically was there any improvement in sensitivity to Ara-C following cytokine priming. S-phase data on all 19 marrows were similarly variable either before or after cytokine preincubation. There was no discernible correlation between clonogenic and kinetic data, nor could any relationship be established between in vitro findings and the FAB subtypes of patients or clinical outcomes. In summary, it would appear that the cell-cycle status of AML cells is likely to be only one of many contributory factors governing the sensitivity of AML progenitors to Ara-C. The clinical response of AML patients to cytokine therapy in association with cell-cycle-specific cytotoxic agents may therefore be variable and unpredictable.
Topical nicotinamide compared with clindamycin gel in the treatment of inflammatory acne vulgaris.
BACKGROUND: Systemic and topical antimicrobials are effective in the treatment of inflammatory acne vulgaris; however, widespread use of these agents is becoming increasingly associated with the emergence of resistant pathogens raising concerns about microorganism resistance and highlighting the need for alternative nonantimicrobial agents for the treatment of acne. Nicotinamide gel provides potent antiinflammatory activity without the risk of inducing bacterial resistance. METHODS: In our double-blind investigation, the safety and efficacy of topically applied 4% nicotinamide gel was compared to 1% clindamycin gel for the treatment of moderate inflammatory acne vulgaris. Seventy-six patients were randomly assigned to apply either 4% nicotinamide gel (n = 38) or 1% clindamycin gel (n = 38) twice daily for 8 weeks. Efficacy was evaluated at 4 and 8 weeks using a Physician's Global Evaluation, Acne Lesion Counts, and an Acne Severity Rating. RESULTS: After 8 weeks, both treatments produced comparable (P = 0.19) beneficial results in the Physician's Global Evaluation of Inflammatory Acne; 82% of the patients treated with nicotinamide gel and 68% treated with clindamycin gel were improved. Both treatments produced statistically similar reductions in acne lesions (papules/pustules; -60%, nicotinamide vs. -43%, clindamycin, P = 0.168), and acne severity (-52% nicotinamide group vs. -38% clindamycin group, P = 0.161). CONCLUSIONS: These data demonstrate that 4% nicotinamide gel is of comparable efficacy to 1% clindamycin gel in the treatment of acne vulgaris. Because topical clindamycin, like other antimicrobials, is associated with emergence of resistant microorganisms, nicotinamide gel is a desirable alternative treatment for acne vulgaris.
Evaluation of water-soluble pneumocandin analogs L-733560, L-705589, and L-731373 with mouse models of disseminated aspergillosis, candidiasis, and cryptococcosis.
The activities of the water-soluble pneumocandin derivatives L-733560, L-705589, and L-731373 were evaluated in mouse models of disseminated aspergillosis, candidiasis, and cryptococcosis and were compared with those of commercially available antifungal agents. Pneumocandins are inhibitors of 1,3-beta-D-glucan synthesis. In the aspergillosis model, L-733560 and L-705589 significantly prolonged the survival of DBA/2N mice challenged intravenously with Aspergillus fumigatus conidia. L-733560 and L-705589 exhibited efficacies comparable to that of amphotericin B (AMB) with 90% effective doses of 0.48, 0.12, and 0.36 mg/kg of body weight, respectively. Two mouse models of disseminated candidiasis were used to evaluate these compounds. In both models, mice were challenged intravenously with Candida albicans. In a C. albicans survival model with DBA/2N and CD-1 mice, the efficacy of L-733560 was comparable to that of AMB, while L-731373 and L-705589 were somewhat less active. In a previously described C. albicans target organ kidney assay, the pneumocandin analogs and AMB at doses of > or = 0.09 mg/kg were effective in sterilizing kidneys, while fluconazole and ketoconazole were considerably less active and did not sterilize kidneys when they were used at concentrations of < or = 100 mg/kg. Although orally administered L-733560 showed activity in both candidiasis models, its efficacy was reduced compared with that of parenterally administered drug. In a disseminated cryptococcosis mouse model that measures the number of CFU of Cryptococcus neoformans per gram of brain and spleen, L-733560 at 10 mg/kg was ineffective in reducing the counts in organs, while AMB at 0.31 mg/kg sterilized the organs. These results indicate that the pneumocandins may be beneficial as potent parenterally administered therapeutic agents for disseminated aspergillosis and candidiasis.
Role of CD8 T cells in primary Chlamydia infection.
The role of CD4 and CD8 T cells in primary Chlamydia trachomatis pneumonia was investigated by using in vivo depletion techniques to eliminate T-cell populations. Reduction of either CD4 T cells or CD8 T cells caused a significant increase in organism burden in the lungs, as measured by both quantitative culture and detection of chlamydial antigen on day 14 postinfection. Chlamydia-specific antibody levels in plasma or antigen-induced gamma interferon (IFN-gamma) production by spleen cells was dramatically reduced by depletion of CD4 cells. The reduction in IFN-gamma achieved by depletion of CD8 cells did not reach statistical significance. In the survival studies, depletion of CD4 cells led to a significant increase in mortality. Although there was a trend toward higher mortality, depletion of CD8 cells did not significantly increase mortality. The role of CD8 T cells in host defense was clarified in studies using beta 2-microglobulin-deficient (major histocompatibility class I antigen-deficient, C1D) mice which are defective in CD8 T-cell function. In this model, a significant increase in organism burden was seen during infection in C1D mice compared with that C57BL/6 controls and a significant increase in mortality was observed as well. However, surviving C1D mice were able to clear the infection by day 34. C1D mice had increased numbers of CD4 T cells in both the spleen and the lungs during infection compared with those of C57BL/6 controls. IFN-gamma in C57BL/6 mice was produced by both CD4 and CD8 cells. Thus, there is a protective role for both CD4 and CD8 cells in host defense against Chlamydia infection, but the former appear to be dominant.
Replication of centromere II of Schizosaccharomyces pombe.
The centromeric DNAs of Schizosaccharomyces pombe chromosomes resemble those of higher eukaryotes in being large and composed predominantly of repeated sequences. To begin a detailed analysis of the mode of replication of a complex centromere, we examined whether any sequences within S. pombe centromere II (cen2) have the ability to mediate autonomous replication. We found a high density of segments with such activity, including at least eight different regions comprising most of the repeated and unique centromeric DNA elements. A physical mapping analysis using two-dimensional gels showed that autonomous replication initiated within the S. pombe sequences in each plasmid. A two-dimensional gel analysis of replication on the chromosomes revealed that the K and L repeat elements, which occur in multiple copies at all three centromeres and comprise approximately 70% of total centromeric DNA mass in S. pombe, are both sites of replication initiation. In contrast, the unique cen2 central core, which contains multiple segments that can support autonomous replication, appears to be repressed for initiation on the chromosome. We discuss the implications of these findings for our understanding of DNA replication and centromere function.
In vivo evaluation of three acid-stable azalide compounds, L-701,677, L-708,299 and L-708,365 compared to erythromycin, azithromycin and clarithromycin.
L-701,677, L-708,299 and L-708,365 are novel azalide derivatives of erythromycin that exhibit improved acid stability over erythromycin, azithromycin and clarithromycin. The half-life in aqueous solution at pH = 2.1 of these compounds ranged from 0.3 hour for erythromycin to 16.2 hours for L-708,299. The rank order of half-life in acid solution from most to least stable was L-708,299 > L-701,677 > L-708,365 > azithromycin = clarithromycin > erythromycin. In a disseminated Streptococcus pyogenes mouse infection model, azithromycin and L-708,365 were slightly more efficacious than clarithromycin, L-701,677 and L-708,299; all 5 compounds being more active than erythromycin. In a Klebsiella pneumoniae pulmonary challenge mouse model, azithromycin, L-701,677, L-708,299 and L-708,365 were all equal in efficacy and at least four-fold more active than clarithromycin and erythromycin. Clarithromycin, L-708,365 and interestingly erythromycin, showed greater bacterial clearance than azithromycin, L-701,677 and L-708,299 in a localized infection model that measured clearance of Staphylococcus aureus from mouse thigh tissues. Our results indicate that L-701,677, L-708,299 and L-708,365 exhibit improved acid stability and were at least equally efficacious as presently marketed macrolide/azalide antibiotics.
Incorporation of tributyrin enhances the expression of a reporter gene in primary and immortalized cell lines.
Advancing the efficiency of foreign gene transfection can be accomplished by improving its DNA delivery or expression or varying the composition of the DNA construct. A novel method of enhancing gene expression by incorporating triacylglycerol into a transfection protocol is described. The triacylglycerol form of butyric acid was chosen because the addition of the free fatty acid to cells increases gene transcription. The effects of this lipid moiety on transfected gene expression were determined for a range of promoters and cell types. In several cases, inclusion of tributyrin resulted in a greater increase in the production of the gene marker product luciferin than that found for the inclusion of free butyric acid. Overall, the relative effects of tributyrin and free butyric acid differ quite markedly for different cell types and promoters. Thus, tributyrin may be a viable alternative to butyric acid in transfection systems where the free fatty acid has little effect.
Yesterday's research: today's standards.
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Serum levels of 2,3,7,8-tetrachlorodibenzo-p-dioxin in phenoxy herbicide sprayers.
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The effect of rh-cytokines on the sensitivity of normal human CFU-GM progenitors to Ara-C and on the S-phase activity of light density human bone marrow cells.
This study examines the effect of pre-incubation in liquid phase of normal human CFU-GM progenitors with recombinant human (rh) cytokines prior to exposure to cytosine arabinoside (Ara-C) in clonogenic culture. Light density marrow cells (LMDCs) were preincubated in Biorich (chemically defined serum-free complete medium) with G + GM-CSF or IL-3 prior to semi-solid culture with Ara-C (10(-4) M-10(-12) M). Cell cycle analysis was performed by flow cytometry pre- and post-rh-cytokine treatment. Data from 26 normal marrows studied clonogenically, demonstrated a 60% reduction in CFU-GM with 10(-4) M Ara-C. Preincubation in Biorich medium with the addition of G + GM-CSF or IL-3 caused a significant enhancement of sensitivity to Ara-C across the dose curve. Biorich medium alone had an apparent protective effect resulting in amelioration of the cytotoxic effect of Ara-C. Cell cycle analysis of eight subjects showed significant recruitment into S-phase following pre-treatment with cytokines. A reduction in S-phase activity was noted in cells pre-incubated in Biorich alone. In summary, it would appear that cytokines can enhance the sensitivity of normal CFU-GM to Ara-C in vitro possibly due to an increase in S-phase activity. Pre-incubation in nutrient medium without cytokines resulted in cell quiescence.
Oral premedication for local anesthesia in plastic surgery: prospective, randomized, blind comparison of lorazepam and temazepam.
Patients undergoing plastic surgical procedures under local anesthesia as inpatients were entered into a phase III randomized, blind trial designed to compare two commonly used oral premedications, lorazepam and temazepam. The effects of the drugs on each patient's memory, pain, sedation, and anxiety were assessed by questions asked of the patient, the nurse, and the surgeon. Analysis was based on 100 randomized patients. Lorazepam had a significantly greater amnesic effect (p < 0.0001), resulted in less pain with the local anesthetic injection (p = 0.006), and had a greater sedative effect than temazepam (p < 0.0001, patient's assessment; p = 0.005, observers' assessments). There was no significant difference in anxiolysis between the two premedications (p = 0.20). If premedication is indicated, we advocate the use of lorazepam rather than temazepam as premedication for plastic surgical procedures to be performed under local anesthesia, provided there is adequate postoperative supervision.
Perspicacity and the physician.
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Long-term culture and molecular biological studies highlight differences in relative BCR-ABL expression levels in the peripheral blood and bone marrow of a patient with chronic granulocytic leukaemia.
A patient with accelerating Ph+ve chronic granulocytic leukaemia (CGL) was considered for autologous BMT using marrow 'purged' by 4 weeks long-term culture (LTC). Efficacy of purging was determined using reverse transcriptase PCR for BCR-ABL mRNA transcripts b2a2 and b3a2. Peripheral blood and bone marrow were compared. Three observations emerged: (i) the initial b2a2:b3a2 ratios for unmanipulated blood and marrow were different with values of 9:1 and 2:1 respectively; (ii) both transcripts were successfully 'purged' with LTC of blood but not marrow; and (iii) LTC of marrow caused a transient increase in relative levels of b3a2 mRNA and a corresponding reduction in the b2a2 signal. This is the first case where such differences have been demonstrated in association with LTC.
Conservative management of squamous cell carcinoma of the anal canal.
The treatment of anal carcinoma with concurrent chemo/radiotherapy has largely replaced abdominoperineal resection as the primary management. This report details the outcome of 62 patients with anal carcinoma treated at a single institution over a 10 year period, during which this approach has become the mainstay of therapy. Of the 34 patients treated with combination radiotherapy and chemotherapy (5-fluorouracil and mitomycin-C), 31 were evaluable and a complete response was achieved in 77%. The estimated 5 year failure-free survival was 67% and the overall survival was 81%. The overall survival was superior to that in patients treated with radiotherapy alone. Eighty-four per cent of patients received the treatment as planned, while the remainder had a reduction in the dose of radiation or chemotherapy due to acute toxicity. The use of combination therapy for primary management of anal carcinoma is generally well tolerated, appears to provide a treatment outcome at least equivalent to surgery, and allows preservation of anal function. Concurrent chemo/radiotherapy should be considered in the initial management of patients with anal carcinoma.
Use of anti-CD4+ hybridoma cells to induce Pneumocystis carinii in mice.
A reduction of peripheral CD4+ cell levels has been correlated with the onset of Pneumocystis carinii pneumonia in AIDS patients. Most in vivo drug discovery and development for P. carinii have been conducted in corticosteroid-treated rats. There is need for the development of new small animal models with more selective methods of immunosuppression. This study outlines a new mouse model in which specific depletion of the CD4+ T-lymphocyte population was achieved by subcutaneous injection of G.K1.5 hybridoma cells into C3HeB/FeJ mice. A significant reduction in splenic CD4+ cells was maintained over a 10-week period following a single injection of cells. Circulating anti-CD4+ antibody was detected throughout the 10-week period in hybridoma-injected mice, while circulating antibody was undetectable 4 weeks after repeated injection of purified monoclonal antibody. There was no significant increase in the CD8+ cell populations of the hybridoma-injected mice. P. carinii cysts increased in the lungs of CD4+ T-cell-depleted mice, with the number of cysts detected comparable to levels in dexamethasone-treated mice. High levels of cysts were detected when CD4+ cell populations in the spleen remained below 5% and decreased when CD4+ populations increased above the 5% level. In mice whose CD4+ population was not reduced below 5%, there was no significant increase in P. carinii cysts detected. This study presents a new mouse model with specific immunosuppression requiring a minimum of animal manipulation for use in discovery and development of potential new therapeutics for P. carinii pneumonia.