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Biomedical subjects

K J Smith

Publications and source records attributed to K J Smith.

At least 127 records · Page 7Linked to original sources
PubMed1997

Binding site for C4b-binding protein in vitamin K-dependent protein S fully contained in carboxy-terminal laminin-G-type repeats. A study using recombinant factor IX-protein S chimeras and surface plasmon resonance.

The interaction between vitamin K-dependent protein S and the C4b-binding protein (C4BP) was studied using surface plasmon resonance and genetic engineering. The affinity, as well as association and dissociation rates of the complex, was measured for human and bovine protein S at five different calcium concentrations. The binding to C4BP of six protein hybrids containing different parts of coagulation factor IX and protein S was studied in the absence and presence of calcium. The results show that dissociation of the human protein S-C4BP complex is extremely slow in the presence of > or = 10 microM calcium (k(off) = 7 x 10(-6) s(-1)) and the association rate constant is k(on) = 7 x 10(4) M(-1) s(-1). Human and bovine protein S were found to bind to human C4BP with the same affinity, K(D) = 0.1 nM, but the rates of association and dissociation were higher for the bovine protein S (k(on) = 2 x 10(5) M(-1) s(-1), k(off) = 2 x 10(-5) s(-1)). In the absence of calcium, the affinity for C4BP was reduced by a factor of 65 for human protein S and by a factor of 40 for bovine protein S. The decreased affinity could be mainly attributed to an increased off-rate (12-17-fold), while the on-rate decreased 3-4-fold. The studies using chimeric proteins show that the portion of protein S that is responsible for binding to C4BP is fully contained in the two laminin-G-type repeats, which are homologous to the sex hormone binding globulin (SHBG). All hybrids that contain the laminin-G-type repeats bind to C4BP with the same affinity as recombinant protein S, whereas hybrids lacking these repeats show no detectable binding to C4BP. The present data also suggest that the effect of calcium on the C4BP-binding properties is mediated by calcium binding site(s) in the laminin-G-type repeats.

Animals↗
PubMed1997

HLA class I binding motifs derived from random peptide libraries differ at the COOH terminus from those of eluted peptides.

Recombinant HLA-A2, HLA-B8, or HLA-B53 heavy chain produced in Escherichia coli was combined with recombinant beta2-microglobulin (beta2m) and a pool of randomly synthesised nonamer peptides. This mixture was allowed to refold to form stable major histocompatability complex (MHC) class I complexes, which were then purified by gel filtration chromatography. The peptides bound to the MHC class I molecules were subsequently eluted and sequenced as a pool. Peptide binding motifs for these three MHC class I molecules were derived and compared with previously described motifs derived from analysis of naturally processed peptides eluted from the surface of cells. This comparison indicated that the peptides bound by the recombinant MHC class I molecules showed a similar motif to naturally processed and presented peptides, with the exception of the peptide COOH terminus. Whereas the motifs derived from naturally processed peptides eluted from HLA-A2 and HLA-B8 indicated a strong preference for hydrophobic amino acids at the COOH terminus, this preference was not observed in our studies. We propose that this difference reflects the effects of processing or transport on the peptide repertoire available for binding to MHC class I molecules in vivo.

Amino Acid Sequence↗
PubMed1997

Immunological investigation of chronic inflammatory demyelinating polyradiculoneuropathy.

In order to investigate the hypothesis that chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is an autoimmune disease related to the acute inflammatory form of Guillain-Barre Syndrome (GBS), we studied 40 patients, 40 age and sex matched controls with other forms of peripheral neuropathy (ONP) and 37 controls from the same family or household (FC). We sought antibodies to gangliosides GM1 and LM1 by enzyme linked immunoassay (ELISA) confirmed by immuno-overlay. Only 6 (15%) CIDP patients had IgM antibodies to ganglioside GM1 (GM1) and none had IgG antibodies. We found IgM antibodies to ganglioside LM1 in 2 (5%) and IgG antibodies in 4 (10%) CIDP patients. Antibodies of IgG or IgM class were detected by ELISA to chondroitin sulphate C or sulfatide in up to 7.5% of CIDP patients. There were IgM antibodies in 3 (7.5%) and IgG in 4 (10%) patients against 25, 28 or 36 kD myelin proteins identified by immunoblot. Antibodies to any of these candidate myelin autoantigens were not significantly more frequent in CIDP than FC or ONP controls. Sera from 5 CIDP patients with active disease which subsequently responded to plasma exchange did not induce more demyelination upon intraneural injection into rat sciatic nerve than ONP sera. Serum tumor necrosis factor alpha (TNFalpha) concentrations were not increased in any of the CIDP patients. Serological evidence of Campylobacter jejuni (Cj) infection was present in 4 (10%) CIDP patients. IgM antibodies to cytomegalovirus (CMV) were not detected in any sera. CIDP is not commonly associated with either of these infections or with an antibody-mediated response to any of these glycolipid or myelin autoantigens.

Adult↗
PubMed1997

Merkel cell carcinoma: analysis of clinical, histologic, and immunohistologic features of 132 cases with relation to survival.

BACKGROUND: Merkel cell carcinoma (MCC) is an uncommon malignancy of the skin and has a high rate of recurrence and metastasis. There have been few large studies of the biologic behavior of MCC. OBJECTIVE: Our purpose was to determine whether there were clinical or histologic features of MCC that predict its biologic behavior. METHODS: We reviewed 132 cases of MCC. Clinical and histologic features were correlated with follow-up information to determine whether any of these were associated with prognosis. RESULTS: Clinical information was available on 126 patients; 57 were alive, 1 was alive with tumor, 28 died of tumor, 27 died from other causes, and 14 were lost to follow-up. MCC on the buttock/thigh area or trunk had the worst prognosis, and those on the distal extremities had the best prognosis; however, the difference was not statistically significant. Sex and age were not significant factors. Small cell size, high mitotic rate, and large tumor size were associated with a low survival rate. When cell size was excluded, male sex and depth of invasion were associated with a worse survival, although these were not statistically significant. CONCLUSION: Cell size, mitotic rate, and tumor size are significant factors in relation to the biologic behavior of MCC.

Adolescent↗
PubMed1997

Immunohistochemical nuclear staining for p53, PCNA, and Ki-67 in different histologic variants of basal cell carcinoma.

BACKGROUND: Increased expression of p53 has been found in the majority of basal cell carcinomas (BCCs); however, UV-light-induced signature mutations are present in only about 50% of cases. Increased nuclear staining with an immunohistochemical marker of proliferation, proliferating cell nuclear antigen (PCNA), has been correlated with aggressive behavior in BCC. OBJECTIVE: Our purpose was to determine whether there is any relationship between different histologic variants of BCC and their expression of p53, PCNA, and Ki-67. METHODS: We used immunohistochemical stains for p53, PCNA, and Ki-67, in superficial-multicentric, nodular-noduloulcerative, sclerosing, infiltrative, and metatypical BCC, to determine whether the staining patterns differ in these different histologic variants of BCC. RESULTS: Superficial-multicentric BCCs were negative for p53 in four of eight tumors. Nodular BCC showed moderately intense p53 nuclear staining with some peripheral accentuation. PCNA nuclear staining was greater than Ki-67, and PCNA-positive cells were fewer than 10% in nodular BCC. Sclerosing and infiltrative BCC showed intense p53 nuclear staining with peripheral accentuation. PCNA nuclear staining was greater than Ki-67, and PCNA-positive cells were greater than 30% in the majority of these tumors. Metatypical BCCs showed diffuse intense p53 staining. PCNA nuclear staining was greater than Ki-67, and PCNA-positive cells were greater than 30% in all tumors studied. When overlying actinic keratoses showed p53 staining, the staining did not necessarily correlate with the intensity or even the presence of positive staining in the subjacent BCC. CONCLUSION: There are at least four distinctive patterns for staining of p53, PCNA, and Ki-67 that correlate with different histologic variants of BCC.

Biomarkers, Tumor↗
PubMed1997

Hyaluronidase enhances the therapeutic effect of vinblastine in intralesional treatment of Kaposi's sarcoma. Military Medical Consortium for the Advancement of Retroviral Research (MMCARR).

BACKGROUND: Although intralesional vinblastine has been used with some success in the treatment of cutaneous lesions of Kaposi's sarcoma (KS), lesions commonly recur. When large lesions are treated, frequently there is considerable discomfort and, in some cases, secondary ulceration. Hyaluronidase has been used to increase dispersion of drugs administered by local injection. OBJECTIVE: Our purpose was to determine whether intralesional hyaluronidase administered before intralesional vinblastine increases the dispersion of vinblastine and decreases toxicity. METHODS: We treated six patients who had multiple cutaneous plaque lesions and tumors of KS with intralesional vinblastine, intralesional vinblastine preceded by intralesional hyaluronidase, or intralesional hyaluronidase alone. RESULTS: Both intralesional vinblastine and intralesional vinblastine preceded by intralesional hyaluronidase caused clinical regression of lesions of KS; however, the combination of hyaluronidase and vinblastine was more effective in treating tumor nodules. In addition, lesions treated with hyaluronidase and vinblastine recurred less often than those treated with vinblastine alone and showed no evidence of residual KS in two patients undergoing biopsy between 4 and 6 months after therapy. CONCLUSION: Intralesional hyaluronidase enhances vinblastine in the treatment of cutaneous lesions of KS without adding to the systemic toxicity.

Adult↗
PubMed1997

Depth of morphologic skin damage and viability after one, two, and three passes of a high-energy, short-pulse CO2 laser (Tru-Pulse) in pig skin.

BACKGROUND: CO2 laser energy is absorbed by water, which is present in all tissue. The depth of penetration of CO2 lasers is narrow with minimal reflection, scatter, or transmission. However, thermal damage has limited the usefulness of conventional, continuous-wave CO2 lasers for debridement as demonstrated by wound healing studies. The development of high-energy CO2 lasers, with pulse durations that are less than the thermal relaxation time of tissue, have made vaporization of skin for resurfacing and wound debridement possible because of the decreased risk of thermal damage. OBJECTIVE: This study was performed to evaluate thermal damage produced by a CO2 laser. METHODS: Routine histopathologic examination and nitroblue-tetrazolium chloride (NBTC) staining were used to evaluate the depth of tissue damage and viability in weanling pig skin after one, two, and three passes of the laser. RESULTS: At a pulse energy of 300 mJ, with a pulse duration of 60 microseconds, one pass of the laser produced vaporization of the epidermis with minimal thermal damage. Two passes produced areas of denatured collagen with loss of viable cells in the superficial papillary dermis. Three passes extended the damage into the papillary dermis. CONCLUSION: Hyalinization of collagen appears to correspond well with the level of thermal damage as measured by NBTC staining. Our findings suggest that the energy necessary to vaporize the dermis may be greater than that needed to vaporize epidermis.

Animals↗
PubMed1997

5-fluorouracil iontophoretic therapy for Bowen's disease.

BACKGROUND: Topical 5-fluorouracil (5-FU) is an accepted therapy for Bowen's disease. Recurrences with this method have been attributed to deep follicular involvement and poor patient compliance because of the prolonged treatment time required. OBJECTIVE: We sought to determine whether iontophoresis of 5-FU is an effective therapy for Bowen's disease. METHODS: Twenty-six patients with biopsy-proven Bowen's disease received eight 5-FU iontophoretic treatments in 4 weeks. Local excision was done 3 months after the last treatment. The specimens were step-sectioned and evaluated for any histologic evidence of bowenoid changes. RESULTS: Only 1 of 26 patients showed histologic evidence of Bowen's disease 3 months after treatment. CONCLUSION: 5-FU iontophoresis appears to be a safe, effective, and well-tolerated therapy for Bowen's disease.

Aged↗
PubMed1997

Histopathologic features seen with different animal models following cutaneous sulfur mustard exposure.

In an effort to understand the pathophysiology of sulfur mustard (2,2' dichlorodiethyl sulfide, HD)-induced cutaneous lesions, a number of animal models have been used. Animal models have been and will continue to be used in the development of therapeutic strategies to protect against and/or moderate lesions, and to potentiate wound healing after HD exposure. Upon reviewing the histopathologic features seen after HD-exposure, we propose roles for different animal models in HD-research. Hematoxylin and eosin slides from protocols done originally as dose response studies for either liquid or vapor HD-exposures were examined. The animal models reported include the hairless guinea pig (HGP), weanling pig (WP), mouse ear (ME) and hairless mouse (HM). In all these animal models. HD induces subepidermal blister formation as well as epidermal cell death. The HGP appears to be the most sensitive model for epidermal necrosis. The HGP and, to a lesser degree, the HM react with a marked neutrophilic infiltrate. The ME provides a quantitative measure for HD effects and a mild inflammatory infiltrate similar to what is seen in human skin. Doses necessary to produce microblister formation in the WP are usually associated with more significant stromal and vascular changes than in other animal models. In addition to a quantitative measure of the HD effect and a mild inflammatory response, the cost, as well as the availability of specific antibodies, and DNA and RNA probes and primers gives the ME advantages for both drug screening and for the study of the pathophysiology of HD-induced cutaneous lesions. The sensitivity of the HGP and the abundant experience with vapor exposures establishes a place for this animal model in barrier cream and drug screening. The similarity of WP skin to human skin is important in the study of wound healing after HD exposure, as well as in the study of the pathophysiology of the cutaneous lesion and in more definitive therapeutic studies.

Animals↗
PubMed1997

Evaluation of cross-reacting anti-human antibodies in the euthymic hairless guinea pig model (HGP) suggests that the HGP may be a model for the study of proliferative skin disease.

Animal models have an important role in cutaneous research. The guinea pig has proven to be a useful model in a wide spectrum of these cutaneous studies; however, its usefulness is often compromised by the need for depilation. A euthymic hairless guinea pig (HGP) model avoids the problems associated with depilation. Morphologically, as in human skin, these animals have a multi-cell-layer epidermis. Proliferation kinetic studies, as well as documentation of the degree of immunologic cross-reactivity between available antibodies to human cutaneous antigens, could extend the usefulness of this animal model. We performed a battery of anti-human antibodies on formalin fixed tissue, to a variety of antigens present within the skin and on inflammatory cells. These included CD3, UCHL-1, OPD4, L-26, KP-1, Factor XIIIa, S-100 protein, cytokeratin (AE1, AE3 and CK1), CAM 5.2, vimentin, CD 34, Factor VIII, fibronectin, SM actin, collagen IV, laminin, Bcl-2, p53, Ki-67, and PCNA. Cross-reacting antibodies included: CD3, S-100 protein, cytokeratin (AE1, AE3 and CK1), vimentin, Factor VIII, SM actin, collagen IV, p53, Ki-67, and PCNA. Although this battery of antibodies is limited, the markedly increased staining of Ki-67 and PCNA within keratinocytes in the epidermis as compared to normal human skin reflects a high proliferative rate. In addition, positive staining for p53, Ki-67, and PCNA may be useful in studying effects on cell cycle kinetics and apoptosis.

Actins↗
PubMed1997

Immunohistochemical studies of basement membrane proteins and proliferation and apoptosis markers in sulfur mustard induced cutaneous lesions in weanling pigs.

Sulfur mustard (2,2-dichlorodiethyl sulfide, HD) is a chemical warfare agent that is a threat to both troops and civilians. The focus of HD research has been on intracellular adduct formation leading to apoptosis and/or necrosis in cutaneous lesions. However, there is work which suggests that HD may have a more direct effect on the basement membrane zone. Immunohistochemical staining to desmosomal proteins, cellular fibronectin, laminin 1, laminin 5, collagen IV, collagen VII, p53, Bcl-2, and PCNA was performed on weanling pig skin exposed to vesicating doses of HD, GB3, an antibody to laminin 5, showed a progressive decrease with loss of expression during the time period of clinical vesiculation. The other basement membrane proteins showed no change or inconsistent changes. PCNA, and p53 staining increased in the overlying epidermis in areas of vesiculation without significant necrosis. Bcl-2 positive cells were decreased or absent after exposure. This study implicates laminin 5 as the main basement membrane protein affected acutely by HD exposure. The patterns of staining of PCNA, Bcl-2, and p53 within the epidermis suggest that apoptosis and cellular necrosis both may play a role in cell death secondary to HD.

Animals↗
PubMed1997

HIV-related eosinophilic folliculitis: a panel discussion.

Eosinophilic folliculitis is a common cause of morbidity in patients infected with the human immunodeficiency virus (HIV) and a marker of the acquired immunodeficiency syndrome (AIDS). No causative organism has yet been identified, although an aberrant Th2-type immune response to a follicular antigen appears relevant to pathogenesis. A variety of treatments have been reported to minimize the inflammatory component, relieve the concomitant pruritus, and/or favorably alter the cutaneous microenvironment.

AIDS-Related Opportunistic Infections↗
PubMed1997

Pityriasis lichenoides et varioliformis acuta in HIV-1+ patients: a marker of early stage disease. The Military Medical Consortium for the Advancement of Retroviral Research (MMCARR).

BACKGROUND: The high incidence of cutaneous disease in HIV-1+ patients may be a marker of the chronic state of immune activation. In addition, specific cutaneous diseases may be related to the pattern and degree of immune dysregulation present in the patients at the time of the eruption. We have observed that HIV-1+ patients with pityriasis lichenoides et varioliformis acuta (PLEVA) were in the early to midstage of HIV-1 disease. MATERIALS AND METHODS: To determine if there was a correlation between the phenotype of the lymphoid infiltrate and surface markers of the epidermis and the known changes in early or late-stage HIV-1 disease, we studied five HIV-1+ patients with PLEVA. Cutaneous biopsy specimens were obtained and immunohistochemical stains were used to determine the expression of ELAM-1, ICAM-1, and HLA-DR and the phenotype of the lymphoid infiltrate. RESULTS: The HIV-1+ patients showed increased expression of HLA-DR on keratinocytes as well as on the mononuclear and dendritic cell populations in the epidermis and dermis. The majority of T cells were activated CD8+ cells. CONCLUSIONS: Immunophenotyping of the inflammatory infiltrate in these patients is consistent with a pattern of immune dysregulation seen only in earlier stages of HIV-1 disease. Thus, PLEVA may be useful as a marker of early to midstages of HIV-1 disease.

Adult↗
PubMed1997

Increased cutaneous toxicity to ionizing radiation in HIV-positive patients. Military Medical Consortium for the Advancement of Retroviral Research (MMCARR).

BACKGROUND: There are reports of increased reactions in HIV-1+ patients to ultraviolet light sometimes in association with medication. In addition, there are also reports of increased morbidity associated with radiation therapy in HIV-1+ patients. METHODS: Three HIV-1+ patients developed cutaneous toxic reactions to radiation therapy; two with Kaposi's sarcoma (KS) and one with non-Hodgkin's lymphoma. CONCLUSIONS: Although the mechanisms which resulted in these reactions are not clear, they may be related to depletion of endogenous scavengers and may be accentuated by the pattern of immune dysregulation present in HIV-1 disease.

Adult↗