Biomedical subjects

B Wang

Publications and source records attributed to B Wang.

At least 271 records · Page 15Linked to original sources

PubMed2000

Amperometric glucose biosensor based on lipid film.

A novel glucose biosensor based on cast lipid film was developed. This model of biological membrane was used to supply a biological environment on the surface of the electrode, moreover it could greatly reduce the interference and effectively exclude hydrophilic electroactive material from reaching the detecting surface. TTF was selected as a mediator because of its high electron-transfer efficiency, and it was incorporated in the lipid film firmly. Glucose oxidase was immobilized in hydrogel covered on the lipid film. The effects of pH, operating potential were explored for the optimum analytical performance by using amperometric method. The response time of the biosensor was less than 20 s, and the linear range is up to 10 mmol l(-1) (corr. coeff. 0.9932) with the detection limit of 2 x 10(-5) mol l(-1). The biosensor also exihibited good stability and reproducibility.

Biosensing Techniques↗

PubMed2000

Silica sol-gel composite film as an encapsulation matrix for the construction of an amperometric tyrosinase-based biosensor.

An amperometric tyrosinase enzyme electrode for the determination of phenols was developed by a simple and effective immobilization method using sol-gel techniques. A grafting copolymer was introduced into sol-gel solution and the composition of the resultant organic-inorganic composite material was optimized, the tyrosinase retained its activity in the sol-gel thin film and its response to several phenol compounds was determined at 0 mV vs. Ag/AgCl (sat. KCl). The dependences of the current response on pH, oxygen level and temperature were studied, and the stability of the biosensor was also evaluated. The sensitivity of the biosensor for catechol, phenol and p-cresol was 59.6, 23.1 and 39.4 microA/mM, respectively. The enzyme electrode maintained 73% of its original activity after intermittent use for three weeks when storing in a dry state at 4 degrees C.

Biosensing Techniques↗

PubMed2000

Blood eicosanoids and immune indices during fasciolosis in water buffaloes.

The effects of trickle infections of water buffaloes with Fasciola hepatica (60 metacercariae daily during a period of 20 days) on the blood plasma levels of prostaglandin E(2) (PGE2), 6-keto-prostaglandin F(1alpha) (6-keto-PG F(1alpha)) and thromboxane B(2) (TXB2) were assessed. F. hepatica specific IgG and T- and B-lymphocyte ratios were evaluated as indicators of the immune response. Although the applied mode of infection did not result in clinical disease, changes in the plasma eicosanoid pattern were observed. Plasma PGE2 values were significantly elevated in the infected water buffaloes 11 weeks post-infection (w.p.i.). In contrast, transiently but significantly lower TXB2 values than in the uninfected controls were recorded in the phase of chronic fasciolosis. Plasma 6-keto-PGF(1alpha) values were not considerably altered by the infection throughout the study period. F. hepatica-specific IgG were detected from 4 to 21 w.p.i. The proportion of peripheral T- and B-lymphocytes shifted towards B-cells from 2 to 12 w.p.i., gradually returning to control values afterwards. Although the water buffaloes appeared to be rather resistant to trickle infection with F. hepatica, moderate changes in plasma eicosanoid patterns were observed, indicating tissue damage and/or inflammation. Induction of the immune response could be monitored by an increase of F. hepatica-specific IgG, which was paralleled by a relative increase of the B-lymphocyte population.

Animals↗

PubMed2000

Transgenic farm animals: applications in agriculture and biomedicine.

During the last decade, tremendous progress has been made in the area of transgenic farm animals. While there are many important transgenic farm animal applications in agriculture, funding has been very limited and progress has been rather slow in this area. Encouragingly, the potential applications of transgenic farm animals as bioreactors for producing human therapeutic proteins and as organ donors for transplantations in humans have attracted vast funding from the private sectors. Several transgenic animal products are already in various phases of clinical trials. Estimates are, that in the near future, the worlds demands on human pharmaceutical proteins may largely be met by transgenic farm animals. While there are still major challenges ahead in the area of xenotransplantation using transgenic animal organs, transgenic tissues or cells have demonstrated promising results as a potential tool for gene therapy. Recent development on cloning, embryonic stem cells and alternative transgenic methods may further expand the transgenic applications in both agriculture and biomedicine.

Agriculture↗

PubMed2000

Molecular characterization of pncA gene mutations in Mycobacterium tuberculosis clinical isolates from China.

A sample of 35 pyrazinamide (PZA)-resistant and 30 PZA-susceptible clinical isolates recovered from Beijing and Taiyuan City, China were characterized by SSCP and sequence analysis for mutations in the pncA gene that encodes the Mycobacterium tuberculosis PZase. The purpose of this study was to understand the molecular basis and the characteristics of pncA gene mutations and its relation to PZA resistance in M. tuberculosis strains from China. Several mutations with base changes leading to amino acid substitutions were found in the PZA-resistant isolates. No mutations were seen in the 243 PZA-susceptible isolates. Among the 35 PZA-resistant isolates, 32 isolates (91.4%) had nucleotide substitutions, insertions and deletions that resulted in amino-acid substitution; or frameshifts in some strains. Other previously uncharacterized mutations were found as follows: Asn118->Thr, CG insertion at position 501; CC insertion at nucleotide position 403; a 8 base-pair deletion at start codon; Pro54->Thr; AG insertion at 368; Tyr41->His, Ser88->stop, and A insertion at nucleotide position 301. IS6110 subtyping revealed that each strain was unique; indicative of the epidemiologic independence of the isolates.

Adolescent↗

PubMed2000

Activation of EphA2 kinase suppresses integrin function and causes focal-adhesion-kinase dephosphorylation.

Interactions between receptor tyrosine kinases of the Eph family and their ligands, ephrins, are implicated in establishment of organ boundaries and repulsive guidance of cell migration during development, but the mechanisms by which this is achieved are unclear. Here we show that activation of endogenous EphA2 kinase induces an inactive conformation of integrins and inhibits cell spreading, migration and integrin-mediated adhesion. Moreover, EphA2 is constitutively associated with focal-adhesion kinase (FAK) in resting cells. Within one minute after stimulation of EphA2 with its ligand, ephrin-A1, the protein tyrosine phosphatase SHP2 is recruited to EphA2; this is followed by dephosphorylation of FAK and paxillin, and dissociation of the FAK-EphA2 complex. We conclude that Eph kinases mediate some of their functions by negatively regulating integrins and FAK.

3T3 Cells↗

PubMed2000

Imiquimod, a topical immune response modifier, induces migration of Langerhans cells.

Langerhans cells are bone marrow derived dendritic cells that represent the major antigen-presenting cells in the skin. Langerhans cells take up and process antigen within the epidermis and present processed antigen to T lymphocyte in the regional lymph nodes and thus form an integral part of the cutaneous immune response. The cutaneous immune response can be modified by a number of pharmacologic agents, including corticosteroids, cyclosporine, and retinoids as well as physical agents, such as ultraviolet light. For the most part these agents act by suppressing immune function. A topical immune response modifier, imiquimod has been shown to enhance the cutaneous immune response. Imiquimod has anti-viral and anti-tumor effects in animal models and has been approved for the topical treatment of external genital and perianal warts in humans. The biologic activity of imiquimod in part is due to its effect as a cytokine inducer. Preliminary data suggested that imiquimod could have an effect on Langerhans cells. In order to clarify this effect on Langerhans cells, we examined Langerhans cell morphology and migration in imiquimod-treated skin. The density of Ia + cells decreased 2 d after treatment, falling to approximately 43% by day 10. The Ia positive in cells remaining in the skin appeared larger and more dendritic suggesting an activated state. ATPase staining of epidermal sheet confirmed the decreased number of Langerhans cells. To clarify status of Langerhans cells, the activation of B7 was examined. Activation of B7-1 or B7-2 was not detected. Imiquimod, however, did enhance Langerhans cell migration from skin to draining lymph nodes. This enhanced Langerhans cell migration was also associated with an enhanced allergic contact hypersensitivity. These results suggest that the mechanism of modulation of immune response by imiquimod is in part due to effects on Langerhans cells.

Adenosine Triphosphatases↗

PubMed2000

In vitro and in vivo expression of interleukin-1alpha and tumor necrosis factor-alpha mRNA in pemphigus vulgaris: interleukin-1alpha and tumor necrosis factor-alpha are involved in acantholysis.

Keratinocyte-derived cytokines have been implicated in the pathogenesis of a number of skin diseases. In this study we examined the possible role of keratinocyte-derived cytokines in the development of acantholysis in pemphigus vulgaris. Nineteen patients with pemphigus vulgaris, demonstrating the characteristic clinical, pathologic, and immunopathologic findings were studied. In situ immunolabeling demonstrated the presence of two cytokines interleukin-1alpha and tumor necrosis factor-alpha, in lesional and perilesional areas. Results were confirmed by reverse transcriptase-polymerase chain reaction, demonstrating overexpression of both cytokines in vivo. To study the role of these cytokines in the pathogenesis of pemphigus vulgaris both in vitro and in vivo studies were performed. The results of the in vitro study demonstrated that pemphigus vulgaris IgG induced interleukin-1alpha and tumor necrosis factor-alpha mRNA in the skin. The potential pathogenic role of these mediators was demonstrated by a blocking study using antibodies against human interleukin-1alpha and tumor necrosis factor-alpha in keratinocytes cultures. A combination of anti-interleukin-1alpha and anti-tumor necrosis factor-alpha antibodies inhibited in vitro pemphigus vulgaris IgG induced acantholysis. To confirm the role of interleukin-1 and tumor necrosis factor-alpha in pemphigus, we utilized passive transfer studies using interleukin-1 deficient mice (ICE-/-, interleukin-1beta-/-) and tumor necrosis factor-alpha receptor deficient mice (TNFR1R2-/-). Both groups demonstrated a decreased susceptibility to the passive transfer of pemphigus. Our data support the role of cytokines interleukin-1 and tumor necrosis factor-alpha in the pathogenesis of pemphigus vulgaris.

Acantholysis↗

PubMed2000

Loss control of Mcm5 interaction with chromatin in cdc6-1 mutated in CDC-NTP motif.

Saccharomyces cerevisiae Cdc6 plays an essential role in establishing and maintaining the prereplicative complex (pre-RC) by interacting with the origin recognition complex (ORC) and associating with chromatin origins. These interactions are required to load minichromosome maintenance proteins (MCMs) and other initiator proteins onto replication origins. Although the temperature-sensitive cdc6 mutant, cdc6-1, has been widely used for these studies, the molecular mechanism of the cdc6-1 mutation has been unclear. In this study, we have identified a base substitution at Gly260-->Asp, near the CDC-NTP motif. Using a chromatin immunoprecipitation assay (CHIP), we found that cdc6-1 fails to load Mcm5 onto the replication origins. Chromatin fractions were used to study Mcm5 binding in both the wildtype and mutant background. These studies indicated that Cdc6 is also involved in unloading Mcm5 from chromatin. Specifically, the cdc6-1 mutation protein, cdc6(G260D), which failed to load Mcm5 onto replication origins, also failed to unload the Mcm5 protein. Furthermore, the overexpression of wildtype CDC6 accelerated the unloading of Mcm5 from chromatin fractions. In the absence of functional Cdc6, the Mcm5 protein showed nonorigin binding to chromatin with the cell cycle arrested at the G1S phase transition. Our results suggested that the cdc6(G260D) mutant protein fails to assemble an operational replicative complex and that wildtype Cdc6 plays a role in preventing re-replication by controlling the unloading the MCMs from chromatin origins.

Amino Acid Substitution↗

PubMed2000

Molecular mechanism of ultraviolet-induced keratinocyte apoptosis.

This article reviews advances in the study of the molecular mechanisms for ultraviolet (UV)-induced keratinocyte apoptosis, with particular reference to the cytokines tumor necrosis factor-alpha (TNF-alpha) and Fas ligand (FasL). TNF-alpha and FasL induce their respective receptors and then activate caspase enzymes that are critically involved in the apoptotic process. This activation is further amplified by intracellular mitochondria-associated mechanisms. Using gene-targeted knockout mice lacking either the TNF-Rp55 or the TNF-Rp75, we have shown that TNF-alpha plays an important role in UV-induced keratinocyte apoptosis via TNF-Rp55. TNF-Rp55 shares homology with Fas and contains an intracellular death domain. UV seems to directly stimulate cross-linking of Fas, resulting in the engagement of the death machinery. Fas-associated death domain protein (FADD) acts as an adapter protein in both the TNF-Rp55 and Fas death-inducing cascades and is responsible for downstream signal transduction by recruiting caspases. Moreover, signaling of p53 contributes to the induction of apoptosis by regulating Bcl-2 family expression and increasing surface Fas expression. In addition to induction mechanisms of apoptosis, there are numerous inhibitory molecules that play a role in restricting the apoptotic pathway. Thus, the ultimate determination of whether or not a cell undergoes apoptosis after UV radiation is based on the balance between agonist and antagonist pathways.

Animals↗

PubMed2000

Molecular regulation of constitutive expression of interleukin-8 in human pancreatic adenocarcinoma.

Recent studies have shown that interleukin-8 (IL-8) plays an important role in the growth and metastasis of human pancreatic cancer. In the present study, we determined the molecular regulation of constitutive IL-8 expression in human pancreatic cancer cells. Various human pancreatic cancer cell lines were incubated in vitro. Sixty-seven percent of the cell lines constitutively secreted high levels of IL-8, as determined using enzyme-linked immunosorbent assay. Consistently, these cells constitutively expressed high levels of IL-8 mRNA, as determined using Northern blot analysis. To determine the mechanisms of the high steady-state levels of IL-8 mRNA, the IL-8 half-life and transcription rate were measured. There was no significant difference in IL-8 half-life between cells expressing high and low levels of IL-8. However, higher transcription rates and increased IL-8 promoter activity were observed in the cells constitutively expressing high levels of IL-8. Detailed IL-8 promoter analysis using deletion mutation revealed that the region from -85 to -133 bp was essential for the constitutive IL-8 promoter activity. Also, point-mutation analysis indicated that mutation of NF-kappaB, AP-1, or NF-IL-6 binding sites significantly reduced or eliminated the constitutive IL-8 promoter activity. Consistent with the constitutive IL-8 transcription activity, high levels of constitutive NF-kappaB and AP-1 activity were detected in the cells overexpressing IL-8, as determined using electrophoretic mobility shift assay. In addition, transfection of a dominant-negative I-kappaBalpha expression vector (I-kappaBalphaM) inhibited constitutive NF-kappaB activity and IL-8 expression in pancreatic cancer cells. Collectively, our data demonstrated that constitutive NF-kappaB and AP-1 activation contributes to the overexpression of IL-8, which in turn plays an important role in tumor angiogenesis and contributes to the aggressive biology of human pancreatic cancer.

Adenocarcinoma↗

PubMed2000

Regulation of interleukin-8 expression by cellular pH in human pancreatic adenocarcinoma cells.

The role of cellular pH in the expression and regulation of interleukin-8 (IL-8) in human tumor cell lines was determined. Transient exposure to pH ranging from 7.4 to 6.7 induced pH-dependent expression of IL-8 at both the mRNA and protein levels in three different human tumor cell lines, including COLO357 pancreatic adenocarcinoma cells, SW620 colon adenocarcinoma cells, and PC3 prostate adenocarcinoma cells. Investigation of the mechanisms of IL-8 induction in response to acidosis was carried out using the COLO357 human pancreatic cancer cell line. The increased steady-state level of mRNA correlated with an increased transcription rate and stability of IL-8 transcripts. Further experiments indicated that mild acidosis activated the transcription factors NF-kappaB and AP-1 and that the cooperation of these two factors appeared to be essential to the transactivation of the IL-8 gene. Our data demonstrated that low tumor pH contributes to the enhanced expression of IL-8 and plays an important role in tumor progression.

Adenocarcinoma↗

PubMed2000

Identification and characterization of Saccharomyces cerevisiae Cdc6 DNA-binding properties.

Recent studies have shown that Cdc6 is an essential regulator in the formation of DNA replication complexes. However, the biochemical nature of the Cdc6 molecule is still largely unknown. In this report, we present evidence that the Saccharomyces cerevisiae Cdc6 protein is a double-stranded DNA-binding protein. First, we have demonstrated that the purified yeast Cdc6 can bind to double-stranded DNA (dissociation constant approximately 1 x 10(-7) M), not to single-stranded DNA, and that the Cdc6 molecule is a homodimer in its native form. Second, we show that GST-Cdc6 fusion proteins expressed in Escherichia coli bind DNA in an electrophoretic mobility shift assay. Cdc6 antibodies and GST antibodies, but not preimmune serum, induce supershifts of GST-Cdc6 and DNA complexes in these assays, which also showed that GST-Cdc6 binds to various DNA probes without apparent sequence specificity. Third, the minimal requirement for the binding of Cdc6 to DNA has been mapped within its N-terminal 47-amino acid sequence (the NP6 region). This minimal binding domain shows identical DNA-binding properties to those possessed by full-length Cdc6. Fourth, the GST-NP6 protein competes for DNA binding with distamycin A, an antibiotic that chelates DNA within the minor groove of the A+T-rich region. Finally, site-direct mutagenesis studies revealed that the (29)KRKK region of Cdc6 is essential for Cdc6 DNA-binding activity. To further elucidate the function of Cdc6 DNA binding in vivo, we demonstrated that a binding mutant of Cdc6 fails to complement either cdc6-1 temperature-sensitive mutant cells or Deltacdc6 null mutant cells at the nonpermissive temperature. The mutant gene also conferred growth impairments and increased the plasmid loss in its host, indicative of defects in DNA synthesis. Because the mutant defective in DNA binding also fails to stimulate Abf1 ARS1 DNA-binding activity, our results suggest that Cdc6 DNA-binding activity may play a pivotal role in the initiation of DNA replication.

Binding Sites↗

PubMed2000

Nicotine dependence and its familial aggregation in Chinese.

BACKGROUND: Nicotine dependence is a significant public health problem. This study attempted to characterize the prevalence and familial aggregation of nicotine dependence in China. METHODS: In 1998, we initiated a community-based cross-sectional study among residents of the Yuexi County in Anqing, China. A total of 991 current smokers from 488 randomly selected nuclear families were recruited and surveyed by use of the standardized Fagerstrom Test of Nicotine Dependence (FTND) questionnaire and the Revised Tolerance Questionnaire (RTQ). All study subjects were offspring in their respective nuclear families, and 478 male-male pairs (aged 41.7 +/- 12.1 years) were finally used for data analyses, because the number of female current smokers (n = 5) was too small. RESULTS: The correlation coefficient of the FTND and the RTQ scores was as high as 0.84 (P < 0.0001). Nicotine dependence, defined as an FTND score > or =8 or an RTQ score > or =28, had a prevalence of 12.7% and 11.1%, respectively. The respective sibling recurrent risk was 1.7 and 2.4, according to the FTND or the RTQ criteria. The adjusted odds ratios and 95% CI of nicotine dependence of second siblings in families in which the first sibling was nicotine dependent were 2.13 (95% CI: 1.02-4.43) and 3.50 (95% CI: 1.65-7.36) respectively, according to the FTND and RTQ criteria. CONCLUSIONS: The prevalence of nicotine dependence in male current smokers in China was comparable to that reported in previous US and European studies. Our findings suggest that genetic influences may play an important role in vulnerability to nicotine addiction.

Adult↗

PubMed2000

Prognostic factors for survival in malignant melanoma of the eyelid skin.

PURPOSE: This study aimed to determine the prognostic factors for survival and disease-free interval for malignant melanoma of the eyelid skin. METHODS: This was a retrospective, nonrandomized, clinical review. Twenty-four patients with eyelid skin melanoma were identified through a search of the tumor registry at M. D. Anderson Cancer Center. Patients were treated between 1953 and 1994. The follow-up ranged from 3 to 18 years (mean = 9.6 years). Primary treatment in all cases entailed wide local excision of the tumor. Patients in whom regional lymph node metastasis developed underwent parotidectomy or neck dissection, with or without adjuvant chemotherapy or external beam radiation. Descriptive statistics were used to characterize the patients. Survival analysis in terms of disease-free survival and recurrence-free survival was performed using age, sex, location of tumor (upper lid, lower lid, or both), histologic type of melanoma, Breslow thickness, and Clark's level as independent variables for survival. RESULTS: Age, sex, location, and the histologic type of tumor were not significant prognostic indicators for survival in this cohort. Clark's level > or = IV by itself was a statistically significant predictor of decreased survival. In addition, tumors with either Clark's level > or = IV or Breslow thickness > or = 1.5 mm were associated with increased mortality. CONCLUSION: Clark's level > or = IV or Breslow thickness > or = 1.5 mm are poor prognostic indicators for malignant melanomas of the eyelid skin. Clinicians should have a high level of suspicion for occult regional lymph node metastasis when treating patients with these tumor features.

Adult↗

PubMed2000

Effect of obesity on flap and donor-site complications in free transverse rectus abdominis myocutaneous flap breast reconstruction.

The purpose of this study was to assess the effect of obesity on flap and donor-site complications in patients undergoing free transverse rectus abdominis myocutaneous (TRAM) flap breast reconstruction. All patients undergoing breast reconstruction with free TRAM flaps at our institution from February 1, 1989, through May 31, 1998, were reviewed. Patients were divided into three groups based on their body mass index: normal (body mass index <25), overweight (body mass index 25 to 29), obese (body mass index > or =30). Flap and donor-site complications in the three groups were compared. A total of 936 breast reconstructions with free TRAM flaps were performed in 718 patients. There were 442 (61.6 percent) normal-weight, 212 (29.5 percent) overweight, and 64 (8.9 percent) obese patients. Flap complications occurred in 222 of 936 flaps (23.7 percent). Compared with normal-weight patients, obese patients had a significantly higher rate of overall flap complications (39.1 versus 20.4 percent; p = 0.001), total flap loss (3.2 versus 0 percent; p = 0.001), flap seroma (10.9 versus 3.2 percent; p = 0.004), and mastectomy flap necrosis (21.9 versus 6.6 percent; p = 0.001). Similarly, overweight patients had a significantly higher rate of overall flap complications (27.8 versus 20.4 percent; p = 0.033), total flap loss (1.9 versus 0 percent p = 0.004), flap hematoma (0 versus 3.2 percent; p = 0.007), and mastectomy flap necrosis (15.1 versus 6.6 percent; p = 0.001) compared with normal-weight patients. Donor-site complications occurred in 106 of 718 patients (14.8 percent). Compared with normal-weight patients, obese patients had a significantly higher rate of overall donor-site complications (23.4 versus 11.1 percent; p = 0.005), infection (4.7 versus 0.5 percent; p = 0.016), seroma (9.4 versus 0.9 percent; p <0.001), and hernia (6.3 versus 1.6 percent; p = 0.039). Similarly, overweight patients had a significantly higher rate of overall donor-site complications (19.8 versus 11.1 percent; p = 0.003), infection (2.4 versus 0.5 percent; p = 0.039), bulge (5.2 versus 1.8 percent; p = 0.016), and hernia (4.3 versus 1.6 percent; p = 0.039) compared with normal-weight patients. There were no significant differences in age distribution, smoking history, or comorbid conditions among the three groups of patients. Obese patients, however, had a significantly higher incidence of preoperative radiotherapy and preoperative chemotherapy than did patients in the other two groups. A total of 23.4 percent of obese patients had preoperative radiation therapy compared with 12.3 percent of overweight patients and 12.4 percent of normal-weight patients; 34.4 percent of obese patients had preoperative chemotherapy compared with 24.5 percent of overweight patients and 17.7 percent of normal-weight patients. Multiple logistic regression analysis was used to determine the risk factors for flap and donor-site complications while simultaneously controlling for potential confounding factors, including the incidence of preoperative chemotherapy and radiotherapy. In summary, obese and overweight patients undergoing breast reconstruction with free TRAM flaps had significantly higher total flap loss, flap hematoma, flap seroma, mastectomy skin flap necrosis, donor-site infection, donor-site seroma, and hernia compared with normal-weight patients. There were no significant differences in the rate of partial flap loss, vessel thrombosis, fat necrosis, abdominal flap necrosis, or umbilical necrosis between any of the groups. The majority of overweight and even obese patients who undertake breast reconstruction with free TRAM flaps complete the reconstruction successfully. Both such patients and surgeons, however, must clearly understand that the risk of failure and complications is higher than in normal-weight patients. Patients who are morbidly obese are at very high risk of failure and complications and should avoid any type of TRAM flap breast reconstruction.

Adult↗

PubMed2000

Effect of smoking on complications in patients undergoing free TRAM flap breast reconstruction.

Free pedicled transverse rectus abdominis myocutaneous (TRAM) flap breast reconstruction is often advocated as the procedure of choice for autogenous tissue breast reconstruction in high-risk patients, such as smokers. However, whether use of the free TRAM flap is a desirable option for breast reconstruction in smokers is still unclear. All patients undergoing breast reconstruction with free TRAM flaps at our institution between February of 1989 and May of 1998 were reviewed. Patients were classified as smokers, former smokers (patients who had stopped smoking at least 4 weeks before surgery), and nonsmokers. Flap and donor-site complications in the three groups were compared. Information on demographic characteristics, body mass index, and comorbid medical conditions was used to perform multivariate statistical analysis. A total of 936 breast reconstructions with free TRAM flaps were performed in 718 patients (80.9 percent immediate; 23.3 percent bilateral). There were 478 nonsmokers, 150 former smokers, and 90 smokers. Flap complications occurred in 222 (23.7 percent) of 936 flaps. Smokers had a higher incidence of mastectomy flap necrosis than nonsmokers (18.9 percent versus 9.0 percent; p = 0.005). Smokers who underwent immediate reconstruction had a significantly higher incidence of mastectomy skin flap necrosis than did smokers who underwent delayed reconstruction (21.7 percent versus 0 percent; p = 0.039). Donor-site complications occurred in 106 (14.8 percent) of 718 patients. Donor-site complications were more common in smokers than in former smokers (25.6 percent versus 10.0 percent; p = 0.001) or nonsmokers (25.6 percent versus 14.2 percent; p = 0.007). Compared with nonsmokers, smokers had significantly higher rates of abdominal flap necrosis (4.4 percent versus 0.8 percent; p = 0.025) and hernia (6.7 percent versus 2.1 percent; p = 0.016). No significant difference in complication rates was noted between former smokers and nonsmokers. Among smokers, patients with a smoking history of greater than 10 pack-years had a significantly higher overall complication rate compared with patients with a smoking history of 10 or fewer pack-years (55.8 percent versus 23.8 percent; p = 0.049). In summary, free TRAM flap breast reconstruction in smokers was not associated with a significant increase in the rates of vessel thrombosis, flap loss, or fat necrosis compared with rates in nonsmokers. However, smokers were at significantly higher risk for mastectomy skin flap necrosis, abdominal flap necrosis, and hernia compared with nonsmokers. Patients with a smoking history of greater than 10 pack-years were at especially high risk for perioperative complications, suggesting that this should be considered a relative contraindication for free TRAM flap breast reconstruction. Smoking-related complications were significantly reduced when the reconstruction was delayed or when the patient stopped smoking at least 4 weeks before surgery.

Adult↗

PubMed2000

Use of defined mutants to assess the role of the Campylobacter rectus S-layer in bacterium-epithelial cell interactions.

Campylobacter rectus is a periodontal pathogen with a 150-kDa protein on its cell surface. This protein forms a paracrystalline lattice, called the S-layer, surrounding the outer membrane of this gram-negative bacterium. To initiate a genetic analysis of the possible role of the S-layer in the initial interaction of C. rectus with host epithelial cells, C. rectus strains lacking the S-layer protein gene (crsA) were constructed by allelic exchange mutagenesis. Surprisingly, the lack of the S-layer had only a minor effect on the interaction of C. rectus with HEp-2 epithelial cells; CrsA(+) cells were 30 to 50% more adherent than were CrsA(-) bacteria. Since the host cell expression of cytokines appears to play an important role in the pathogenesis of periodontal diseases, the effect of the S-layer on the epithelial cell cytokine response was also examined by quantitative reverse transcriptase PCR and enzyme-linked immunosorbent assay. Although there were no changes in the mRNA levels for the anti-inflammatory cytokines interleukin-1 receptor agonist (IL-1ra), IL-13, and transforming growth factor beta, the expression and secretion of the proinflammatory cytokines IL-6, IL-8, and tumor necrosis factor alpha (TNF-alpha) were significantly induced by both wild-type C. rectus and CrsA(-) bacteria. Interestingly, the kinetics of cytokine induction differed for the CrsA(+) and CrsA(-) bacteria. At early time points, the HEp-2 cells challenged with CrsA(-) bacteria produced higher levels of IL-6, IL-8, and TNF-alpha mRNA and protein than did cells challenged with CrsA(+) bacteria. We conclude that C. rectus may help initiate periodontitis by increasing the expression of proinflammatory cytokines and that the S-layer may temper this response to facilitate the survival of C. rectus at the site of infection.

Bacterial Adhesion↗