Bilateral inverted papilloma: A report of two cases and review of the current literature.

Inverted papilloma is locally aggressive tumour which typically presents as a unilateral nasal polyp. Whilst it has a malignant potential it rarely transforms and in its benign form the main concern originates from its locally aggressive nature and substantial propensity to recur. Bilateral disease can also be due to inverted papilloma, sometimes due to direct extension of the tumour, but it can also occur as two distinct lesions. Here we report two cases of bilateral involvement, review the current literature and highlight some important issues on the management and follow-up of this well known neoplasm.

Quinsy trainer.

The implementation of the European Working Time Directive, from the Council of the European Union (93/104/EC), in August 2004 has provoked a change in the working hours of junior doctors in the United Kingdom. With the evolution of the subsequent cross-cover arrangements combined with the modernising of medical careers,(1) training is becoming increasingly important. Here we present a simple method of teaching junior doctors the skills and competencies required to aspirate a peritonsillar abscess or 'quinsy'. The model is easy to construct, low cost and reusable.

Human coronary endothelial cell activation by endotoxin is characterized by NF-kappa B activation and TNF-alpha synthesis.

Tumor necrosis factor-alpha (TNF-alpha), an early inflammatory mediator typically regulated by nuclear factor kappa B (NF-kappa B), plays a critical role in the development of cardiovascular dysfunction in sepsis. While several myocardial cell types synthesize TNF-alpha, the importance of the myocardial endothelium in sepsis-related cardiac cytokine production is unclear. To determine the role of the human coronary artery endothelial cell (HCA-EC) in the cytokine response to endotoxin we measured in vitro TNF-alpha synthesis, TNF-alpha mRNA, and the associated NF-kappa B response to LPS. To determine the magnitude of the HCA-EC response we assessed the TNF-alpha and NF-kappa B response to LPS in a human monocytic cell line (THP-1) as well. We observed an increase in supernatant TNF-alpha from LPS-stimulated HCA-EC (12 h) that was ablated by the proteosome inhibitor, ALLN (N-acetyl-Leu-Leu-norleucinal). Similarly, ALLN-sensitive TNF-alpha was produced by monocytes following LPS, although at concentrations 100-fold higher than HCA-EC. TNF-alpha mRNA from HCA-EC was detected at 60 min in LPS-stimulated cells, but not in unstimulated cells or cells pretreated with ALLN. NF-kappa B p50/p65 subunits were detectable in endothelial nuclear protein 60 min following LPS. In contrast, NF-kappa B subunits from monocytes were detected at 15 min. Also, while ALLN only attenuated endothelial NF-kappa B translocation, monocyte NF-kappa B translocation was completely inhibited. These data suggest endotoxin-stimulated human coronary endothelial cells express TNF-alpha, which is regulated in part by NF-kappa B activation, in a manner and degree distinct from human monocytes.

Differential activation of coronary and pulmonary endothelial cells by thermal injury.

Remote organ dysfunction during resuscitation of severe thermal injury is characterized by early, transient pulmonary insufficiency and cardiac contractile dysfunction. Thermal injury is typified by profound systemic alterations of endothelial immunological, vasoactive, and barrier functions. The unique location of this ubiquitous, fragile monolayer makes it vulnerable to circulating serum factors created at remote cutaneous wounds. We examined endothelial "activation" in 2 distinct cell types, human coronary and pulmonary endothelial cells (EC), after severe thermal injury. By using human serum isolated at specific times after thermal injury ("early" [2 h post-burn] or "late" [26 h post-burn]), the endothelial release of vasoactive mediators, ICAM-1 expression, and monolayer permeability were assessed in vitro. Early burn serum enhanced coronary EC vasoconstrictor (ET-1) release and ICAM expression, inhibited vasodilator (PGI2) release, but had no effect on permeability. Conversely, under similar conditions, pulmonary EC PGI2 release and permeability were enhanced, ET-1 release was diminished, but ICAM was unaffected. Late burn serum enhanced vasodilator (NO) release and permeability to albumin in both coronary and pulmonary EC, whereas ET-1 release was inhibited. Under these conditions, only pulmonary ICAM expression was significantly enhanced. These data suggest that human endothelium isolated from divergent vascular beds are activated by burn injury in a unique manner for time post-burn and vascular site of cell origin.

Colorimetric assay to quantify macromolecule diffusion across endothelial monolayers.

Endothelial "capillary leak", the loss of vascular integrity in response to noxious stimuli, is characterized by extravasation of protein-richfluidfrom capillary lumen into surrounding tissue interstitium. This increase in vascular permeability, in response to inflammatory mediators, correlates with endothelial cell contraction and the formation of intercellular gaps within the monolayer. However, in vivo assessment of paracellular solute flow between endothelial cells may be complicated by multiple uncontrolled parameters. In vitro examinations of endothelial barrier leak have relied on electrical impedence or macromolecule diffusion techniques to determine the details pertinent to capillary barrier function. In this report, a simple, sensitive, nonradioactive, colorimetric assay to quantify the leak of a labeled protein marker across endothelial monolayers is described. This procedure avoids the hazards of radioisotope labels and the technical limitations of electrical resistance technology.

Thrombin-mediated permeability of human microvascular pulmonary endothelial cells is calcium dependent.

BACKGROUND: In response to inflammation, endothelial cytoskeleton rearrangement, cell contraction, and intercellular gap formation contribute to a loss of capillary barrier integrity and resultant interstitial edema formation. The intracellular signals controlling these events are thought to be dependent on intracellular calcium concentration ([Ca2+]i). We hypothesized that, in human pulmonary microvascular endothelial cells, a thrombin-induced increase in permeability to albumin would be dependent on Ca2+i and subsequent actin cytoskeleton rearrangements. METHODS: Human lung microvascular endothelial cells, grown on 0.4 micromol/L pore membranes, were activated with 10 nmol/L human thrombin in Hank's balanced salt solution/0.5% fetal bovine serum. Select cultures were pretreated (45 minutes) with 4 micromol Fura-2/AM to chelate Ca2+i. Permeability was assessed as diffusion of bovine serum albumin/biotin across the monolayer. Similarly treated cells were stained with rhodamine-phalloidin to demonstrate actin cytoskeletal morphology. Separately, cells loaded 2 micromol Fura-2/AM were assessed at OD340/380nm after thrombin exposure to detect free Ca2+i. RESULTS: Intracellular Ca2+ levels increased 15-fold (2 seconds) and fell to baseline (10 minutes) after thrombin. Permeability increased 10-fold (30 minutes), and a shift from cortical to actin stress fiber morphology was observed. Chelation of Ca2+i diminished permeability to baseline and reduced the percentage of cells exhibiting stress fiber formation. CONCLUSION: Thrombin stimulates pulmonary capillary leak by affecting the barrier function of activated pulmonary endothelial cells. These data demonstrate a thrombin-stimulated increase in monolayer permeability, and cytoskeletal F-actin stress fibers were, in part, regulated by endothelial Ca2+i. This early, transient rise in Ca2+i likely activates downstream pathways that more directly affect the intracellular endothelial structural changes that control vascular integrity.

Recombinant phycobiliproteins. Recombinant C-phycocyanins equipped with affinity tags, oligomerization, and biospecific recognition domains.

A family of specific cloning vectors was constructed to express in the cyanobacterium Anabaena sp. PCC7120 recombinant C-phycocyanin subunits with one or more different tags, including the 6xHis tag, oligomerization domains, and the streptavidin-binding Strep2 tag. Such tagged alpha or beta subunits of Anabaena sp. PCC7120 C-phycocyanin formed stoichiometric complexes in vivo with appropriate wild-type subunits to give constructs with the appropriate oligomerization state and normal posttranslational modifications and with spectroscopic properties very similar to those of unmodified phycocyanin. All of these constructs were incorporated in vivo into the rod substructures of the light-harvesting complex, the phycobilisome. The C-terminal 114-residue portion of the Anabaena sp. PCC7120 biotin carboxyl carrier protein (BCCP114) was cloned and overexpressed and was biotinylated up to 20% in Escherichia coli and 40% in wild-type Anabaena sp. His-tagged phycocyanin beta--BCCP114 constructs expressed in Anabaena sp. were >30% biotinylated. In such recombinant phycocyanins equipped with stable trimerization domains, >75% of the fusion protein was specifically bound to streptavidin- or avidin-coated beads. Thus, the methods described here achieve in vivo production of stable oligomeric phycobiliprotein constructs equipped with affinity purification tags and biospecific recognition domains usable as fluorescent labels without further chemical manipulation.

Probing the photoreaction mechanism of phytochrome through analysis of resonance Raman vibrational spectra of recombinant analogues.

Resonance Raman spectra of native and recombinant analogues of oat phytochrome have been obtained and analyzed in conjunction with normal mode calculations. On the basis of frequency shifts observed upon methine bridge deuteration and vinyl and C(15)-methine bridge saturation of the chromophore, intense Raman lines at 805 and 814 cm(-)(1) in P(r) and P(fr), respectively, are assigned as C(15)-hydrogen out-of-plane (HOOP) wags, lines at 665 cm(-)(1) in P(r) and at 672 and 654 cm(-)(1) in P(fr) are assigned as coupled C=C and C-C torsions and in-plane ring twisting modes, and modes at approximately 1300 cm(-)(1) in P(r) are coupled N-H and C-H rocking modes. The empirical assignments and normal mode calculations support proposals that the chromophore structures in P(r) and P(fr) are C(15)-Z,syn and C(15)-E,anti, respectively. The intensities of the C(15)-hydrogen out-of-plane, C=C and C-C torsional, and in-plane ring modes in both P(r) and P(fr) suggest that the initial photochemistry involves simultaneous bond rotations at the C(15)-methine bridge coupled to C(15)-H wagging and D-ring rotation. The strong nonbonded interactions of the C- and D-ring methyl groups in the C(15)-E,anti P(fr) chromophore structure indicated by the intense 814 cm(-1) C(15) HOOP mode suggest that the excited state of P(fr) and its photoproduct states are strongly coupled.

Cardiovascular effect of 7.5% sodium chloride-dextran infusion after thermal injury.

HYPOTHESIS: Clinical study can help determine the safety and cardiovascular and systemic effects of an early infusion of 7.5% sodium chloride in 6% dextran-70 (hypertonic saline-dextran-70 [HSD]) given as an adjuvant to a standard resuscitation with lactated Ringer (RL) solution following severe thermal injury. DESIGN: Prospective clinical study. SETTING: Intensive care unit of tertiary referral burn care center. PATIENTS: Eighteen patients with thermal injury over more than 35% of the total body surface area (TBSA) (range, 36%-71%) were studied. INTERVENTIONS: Eight patients (mean +/- SEM, 48.2% +/- 2% TBSA) received a 4-mL/kg HSD infusion approximately 3.5 hours (range, 1.5-5.0 hours) after thermal injury in addition to routine RL resuscitation. Ten patients (46.0% +/- 6% TBSA) received RL resuscitation alone. MAIN OUTCOME MEASURES: Pulmonary artery catheters were employed to monitor cardiac function, while hemodynamic, metabolic, and biochemical measurements were taken for 24 hours. RESULTS: Serum troponin I levels, while detectable in all patients, were significantly lower after HSD compared with RL alone (mean +/- SEM, 0.45 +/- 0.32 vs 1.35 +/- 0.35 microg/L at 8 hours, 0.88 +/- 0.55 vs 2.21 +/- 0.35 microg/L at 12 hours). While cardiac output increased proportionately between 4 and 24 hours in both groups (from 5.79 +/- 0.8 to 9.45 +/- 1.1 L/min [mean +/- SEM] for HSD vs from 5.4 +/- 0.4 to 9.46 +/- 1.22 L/min for RL), filling pressure (central venous pressure and pulmonary capillary wedge pressure) remained low for 12 hours after HSD infusion (P = .048). Total fluid requirements at 8 hours (2.76 +/- 0.7 mL/kg per each 1% TBSA burned [mean +/- SEM] for HSD vs 2.67 +/- 0.24 mL/kg per each 1% TBSA burned for RL) and 24 hours (6.11 +/- 4.4 vs 6.76 +/- 0.75 mL/kg per each 1% TBSA burned) were similar. Blood pressure remained unchanged, and serum sodium levels did not exceed 150 +/- 2 mmol/L (mean +/- SD) in either group. CONCLUSIONS: The absence of deleterious hemodynamic or metabolic side effects following HSD infusion in patients with major thermal injury confirms the safety of this resuscitation strategy. Postburn cardiac dysfunction was demonstrated in all burn patients through the use of cardiospecific serum markers and pulmonary artery catheter monitoring. Early administration of HSD after a severe thermal injury may reduce burn-related cardiac dysfunction, but it had no effect on the volume of resuscitation or serum biochemistry values.

Thermal injury alters endothelial vasoconstrictor and vasodilator response to endotoxin.

BACKGROUND: The unique location of the endothelium makes it vulnerable to injury from circulating factors created at remote wounds. In this study, we examined the effect of a sequential burn and lipopolysaccharide (LPS) challenge on endothelial function in vitro. METHODS: Human umbilical vein endothelial cells treated with 20% human serum isolated from burn patients (>40% total burn surface area) at 2 and 24 hours postinjury. Cultures were subsequently treated with Escherichia coli LPS:0111:B4 (0.10-100ng/mL). Endothelin-1 (ET-1), 6-ketoPGF1a, and NO2/NO3 were detected by using specific enzyme immunoassays. RESULTS: Burn serum did not alter endothelial ET-1, PGI2, or NO secretion compared with Control serum. LPS significantly enhanced 6-ketoPGF1a (54,242+/-14,466 pg/10(6) cells) and NO2/ NO3 (723+/-210 microM) secretion, but not ET-1 compared with Control serum alone (3,878+/-963 and 219+/-110). Burn serum pretreatment significantly enhanced the ET-1 response to LPS (303+/-36 pg/10(6) cells vs. 193+/-47). The 6-ketoPGF1a (16,509+/-3,785) and NO2/NO3 (354+/-98) responses to Burn/LPS were significantly diminished compared with Control/LPS. Although this level of 6-ketoPGF1a was elevated compared with Control alone (7,518+/-2,299), NO2/NO3 was unchanged (significance at p < 0.05). CONCLUSION: Thermal injury may prime remote endothelium and alter the response to a septic focus with an enhanced vasoconstrictor (ET-1) and diminished vasodilator (PGI2/NO) response, a situation that may contribute to postburn distal organ injury.

Thermal injury alters myocardial sarcoplasmic reticulum calcium channel function.

BACKGROUND: We have previously shown that a major cutaneous thermal injury produces profound cardiac contractile dysfunction despite adequate resuscitation. While the molecular basis of this dysfunction is unknown, recent work has suggested that alterations in calcium flux between the myocyte sarcoplasmic reticulum (SR) to the cytoplasm may play a role. MATERIALS AND METHODS: To determine if thermal injury-induced contractile dysfunction is related to intracellular calcium transport across the SR membrane, we accessed myocardial microsomal preparations from scalded (43% TBSA) guinea pigs for the ability of the cardiac calcium efflux channel to bind radiolabeled ryanodine. Intracellular calcium flux was assessed by fluorescence spectrophotometry. RESULTS: Thermal injury resulted in severe cardiac contractile deficit characterized by loss of LVP and +/-dP/dt despite resuscitation. Analysis of isolated myocyte cultures showed a twofold increase in cytoplasmic [Ca2+]l by 24 h postburn. Competitive binding and Scatchard analysis demonstrated a single, high-affinity binding site present in both sham and burn animal hearts. Myocardial membrane vesicles revealed a significantly enhanced number of calcium efflux channels in the open configuration at both 8 and 24 h following thermal injury compared to time-matched shams (1.07 +/- 0.01 and 0.95 +/- 0.06 vs 0.85 +/- 0.01 pmol bound/mg protein, P < 0.05). The data indicate that altered function of the myocardial transmembrane SR calcium efflux channel following thermal injury was associated with elevated [Ca2+]l and contractile dysfunction. CONCLUSIONS: We conclude that postburn cardiac dysfunction may partly be a result of elevated cytoplasmic calcium concentrations and diminished regulation of SR calcium efflux channel activity.

Evaluation of troponin-I as an indicator of cardiac dysfunction after thermal injury.

BACKGROUND: Biochemical serum markers commonly used to assess human cardiac injury (creatinine phosphokinase, creatine phosphokinase-MB) have been shown to have diminished specificity for detection of cardiac injury in the setting of burn-related soft-tissue and skeletal muscle injury. Laboratory studies have demonstrated that severe cutaneous thermal injury is associated with cardiac contractile dysfunction and a corresponding elevation in serum cardiac troponin-I (cTn-I) in several species. METHODS: Twenty-three patients admitted to a tertiary care burn referral center were evaluated. Patients were monitored with pulmonary artery catheters, and creatinine phosphokinase, creatine phosphokinase-MB, and cTn-I levels were determined for 24 hours. Using a database, 6,722 burn patients were reviewed to determine the incidence of preexisting cardiac disease and postburn cardiac complications. RESULTS: All patients had persistent sinus tachycardia (>115 beats per minute) without obvious electrical anomalies. All patients centrally monitored with a pulmonary artery catheter (n=20) maintained a cardiac index of greater than 3.0 L x min(-1) x m(-2) x cTn-I was present (>0.3 ng/mL) within 3.0 hours and elevated (>0.55 ng/mL) at 24 hours for all burns of more than 18% total body surface area. Historically, although only 5% of all admissions manifest acute postburn cardiac complications, 94% of these patients presented with preexisting heart disease. CONCLUSION: Severe thermal injury was associated with a mild elevation in serum troponin-I; however, this did not correlate with overt cardiac morbidity or mortality. Postburn elevation of cTn-I suggested that a subtle degree of cardiac injury was present after a severe thermal injury despite hyperdynamic cardiac function during resuscitation.

Prescribing alcohol in a general hospital: 'not everything in black and white makes sense'.

The policies and practicalities of prescribing alcohol for inpatients at a teaching hospital were examined. Sources of information easily available to hospital medical staff were searched for guidance on the prescription of alcohol. No guidance relevant to clinical practice was found. Current practice in a single hospital was examined using a semistructured staff interview. While nurses and doctors suggested a wide range of indications for prescribing alcohol, most of these are not supported by evidence and for some, such as alcoholism and depression, alcohol would be contra-indicated. The persistence of alcohol prescribing in hospital is based on tradition rather than evidence of its effectiveness. It sends an undesirable message to patients who may be suffering from alcohol-related medical disorders, and it is time to discontinue this outdated clinical practice.

Preconditioning prevents myocardial stunning after cardiac transplantation.

BACKGROUND: Preconditioning has been shown to reduce myocardial stunning after reversible global ischemia. To determine whether preconditioning improves functional recovery after cardiac transplantation, 16 sheep were randomly assigned to a preconditioning protocol or to a control group. METHODS: Preconditioning was achieved with 5 minutes of global ischemia followed by 10 minutes of reperfusion. The heart was then arrested with 1 L of crystalloid cardioplegia, explanted, stored in a transport cooler, and then transplanted into recipient sheep. The total ischemia time was 2 hours. Pressure-volume loops were used to calculate preload recruitable stroke work, the maximum elastance, and diastolic compliance. Linear regression analysis was used to determine the preload recruitable stroke work, maximum elastance, and diastolic compliance-and end-diastolic volume relationship. The area under the regression curve for preload recruitable stroke work was defined as the preload recruitable stroke work area. Biopsies were taken for high-energy phosphates. RESULTS: Systolic function, represented by preload recruitable stroke work area, was preserved after cardiac transplantation in preconditioned animals. Maximum elastance and diastolic compliance were unaffected by preconditioning or ischemia. High-energy phosphates were better preserved in preconditioned animals. CONCLUSION: Preconditioning prevented myocardial stunning and preserved high-energy phosphates after experimental cardiac transplantation.

Redefining the growth of the heterosexual HIV/AIDS epidemic in Chicago.

UNLABELLED: A dramatic shift in the relative distribution of the five categories of heterosexual transmission for AIDS cases diagnosed in Chicago since 1991 prompted a mode-of-transmission validation study of what had become the most frequently reported heterosexual exposure: heterosexual relations with a person with AIDS (PWA) or documented HIV infection whose risk is not specified. METHODS: For 395 cases with originally reported heterosexual exposure, one or more of three supplemental data sources were employed: medical records were reviewed, medical providers were interviewed, and patients or proxies (i.e., spouse, significant other, or family member) were interviewed when possible. When reported HIV exposure could not be validated or reclassified, the transmission category employed was "no identifiable risk" (NIR). RESULTS: Eighty-five percent (336 of 395 cases) were reclassified into different transmission categories. Most notably, 69% (272 of 395 cases) were reclassified into transmission categories that did not involve heterosexual contact, including NIR. The cumulative percentage of cases attributable to heterosexual contact declined from 8% to 5% as a result of reclassification. Additionally, reclassification resulted in a reduction of nearly 50% in the number of AIDS cases attributable to heterosexual contact diagnosed in 1993 and 1994. CONCLUSIONS: In Chicago, an emerging problem in AIDS surveillance appears to be the use of an ambiguous heterosexual exposure category as a default when other information is not readily available. This study has found the growth in AIDS cases among persons exposed to HIV through heterosexual contact to be much slower than previously perceived. This finding may have important implications for the national debate over the extent to which heterosexual people are being infected and how funding and prevention strategies should be prioritized.

Light versus heavy sedation after cardiac surgery: myocardial ischemia and the stress response. Maritime Heart Centre and Dalhousie University.

UNLABELLED: The influence of light versus heavy sedation after coronary artery bypass graft (CABG) surgery on the development of postoperative myocardial ischemia has not been described. After uncomplicated CABG surgery, 50 patients were randomly assigned to receive LOW (n = 24; target Ramsay Sedation Score [RSS] = 2) or HIGH (n = 26; target RSS = 4) sedation with propofol. Analgesia was provided to maintain a visual analog scale (VAS) pain score <7. Myocardial ischemia was identified perioperatively using continuous 3-lead Holter monitoring. By measuring creatine kinase (CK) MB levels preoperatively, at entry to the intensive care unit (ICU), and every 12 h for 48 h; and by obtaining serial 12-lead electrocardiograms (ECG) (preoperatively; 2, 4, 12, 24, and 48 h after ICU admission, 8:00 AM the morning after surgery; and 5 min pre- and postextubation), myocardial infarction was identified. Endocrine stress response was assessed by measuring serum cortisol levels preoperatively, on admission to the ICU, and 24 h postoperatively. In a subset of patients (LOW n = 10, HIGH n = 11), plasma and urinary catecholamine levels were also measured. There were no between-group differences in demographics, operative course, hemodynamic variables, or cortisol levels while in the ICU. The VAS pain score and target RSS were achieved and sustained, and they differed between groups. There were three myocardial infarctions in each group by CKMB criteria alone. No ECG-identifiable myocardial infarction occurred. The ST segment versus time curve (LOW 187 +/- 295 versus HIGH 1071 +/- 2137 mm/min) differed between groups. Urinary and plasma catecholamine levels were similar between groups over the observation period. We conclude that the use of a reduced sedation regimen in combination with adequate analgesia did not result in an increased endocrine stress response or risk of myocardial ischemia. IMPLICATIONS: This randomized study of patients after coronary artery bypass surgery examined whether light (versus heavy) sedation with propofol in the intensive care unit was associated with an increased degree of myocardial ischemia. Using techniques to detect myocardial ischemia, including Holter monitoring, electrocardiogram, and myocardial enzyme measurements, no differences were found. We conclude that light sedation does not increase the endocrine stress response or the risk of myocardial infarction.

Toxic epidermal necrolysis.

Toxic epidermal necrolysis (TEN) is a poorly understood and devastating condition. It is usually diagnosed in a primary care setting. Treatment of severe cases by burn care personnel is usually by referral. In this review, we report excessive mortality rates associated with prolonged use of systemic steroid therapy and delayed referral (more than 1 week from diagnosis). Forty-four consecutive patients admitted to a regional burn center with the diagnosis of TEN over a 14-year period, (0.7% of all admissions) were included. Precipitating factors were identified in 30 cases. Twenty-one patients had known prehospital allergy conditions directly related to the inciting agent. The mean age of this population was 44.9 years, and the mean total body surface area (TBSA) injury was 52.4%. Eighty-four and one-half percent of all patients with TEN were admitted to the ICU. Twenty-four patients required ventilator support. Overall mortality rate was 36%. Nonsurviving patients had a mean age of 61.6 years, compared to 35.3 years for survivors. Nonsurvivors had a mean TBSA of 64.4%, survivors had a mean TBSA of 44%. TEN, although a nonthermal injury, is best managed by personnel experienced in the care of severe thermal injuries. Despite the availability of this expertise, delayed transfer of severe presentations continues to contribute to exceptionally high morbidity and mortality rates.

A cyanobacterial phytochrome two-component light sensory system.

The biliprotein phytochrome regulates plant growth and developmental responses to the ambient light environment through an unknown mechanism. Biochemical analyses demonstrate that phytochrome is an ancient molecule that evolved from a more compact light sensor in cyanobacteria. The cyanobacterial phytochrome Cph1 is a light-regulated histidine kinase that mediates red, far-red reversible phosphorylation of a small response regulator, Rcp1 (response regulator for cyanobacterial phytochrome), encoded by the adjacent gene, thus implicating protein phosphorylation-dephosphorylation in the initial step of light signal transduction by phytochrome.

Two new lignans with activity against influenza virus from the medicinal plant Rhinacanthus nasutus.

Two new lignans, rhinacanthin E (1) and rhinacanthin F (2), were isolated from the aerial parts of the plant Rhinacanthus nasutus. Their structures were established by detailed spectroscopic analysis. These compounds show significant antiviral activity against influenza virus type A.

Purification and characterization of recombinant affinity peptide-tagged oat phytochrome A.

Full-length Avena sativa (oat) phytochrome A (ASPHYA) was expressed in the yeast Saccharomyces cerevisiae and purified to apparent homogeneity. Expression of an ASPHYA cDNA that encoded the full-length photoreceptor with a 15 amino acid 'strep-tag' peptide at its C-terminus produced a single polypeptide with a molecular mass of 124 kDa. This strep-tagged polypeptide (ASPHYA-ST) bound tightly to streptavidin agarose and was selectively eluted using diaminobiotin, with a chromatographic efficiency of 45%. Incubation of ASPHYA-ST with phytochromobilin (P phi B) and the unnatural chromophore precursors, phycocyanobilin (PCB) and phycoerythrobilin (PEB), produced covalent adducts that were similarly affinity purified. Both P phi B and PCB adducts of ASPHYA-ST were photoactive--the P phi B adduct displaying spectrophotometric properties nearly indistinguishable from those of the native photoreceptor, and the PCB adduct exhibiting blue-shifted absorption maxima. Although the PEB adduct of ASPHYA-ST was photochemically inactive, it was intensely fluorescent with an excitation maximum at 576 nm and emission maxima at 586 nm. The superimposability of its absorption and fluorescence excitation spectra established that a single biliprotein species was responsible for fluorescence from the adduct produced when ASPHYA-ST was incubated with PEB. Steric exclusion HPLC also confirmed that ASPHYA-ST and its three bilin adducts were homodimers, as has been established for phytochrome A isolated from natural sources. The ability to express and purify recombinant phytochromes with biochemical properties very similar to those of the native molecule should facilitate detailed structural analysis of this important class of photoreceptors.