Engineered porosity for tissue-integrating, bioresorbable lifetime-based phosphorescent oxygen sensors

Versatile silk protein-based material formats were studied to demonstrate bioresorbable, implantable optical oxygen sensors that can integrate with the surrounding tissues. The ability to continuously monitor tissue oxygenation in vivo is desired for a range of medical applications. Silk was chosen as the matrix material due to its excellent biocompatibility, its unique chemistry that facilitates interactions with chromophores, and the potential to tune degradation time without altering chemical composition. A phosphorescent Pd (II) benzoporphyrin chromophore was incorporated to impart oxygen sensitivity. Organic solvent-based processing methods using 1,1,1,3,3,3-hexafluoro-2-propanol were used to fabricate: 1) silk-chromophore films with varied thickness and 2) silk-chromophore sponges with interconnected porosity. All compositions were biocompatible and exhibited photophysical properties with oxygen sensitivities (i.e., Stern-Volmer quenching rate constants of 2.7-3.2 × 104 M-1) useful for monitoring physiological tissue oxygen levels and for detecting deviations from normal behavior (e.g., hyperoxia). The potential to tune degradation time without significantly impacting photophysical properties was successfully demonstrated. Furthermore, the ability to consistently monitor tissue oxygenation in vivo was established via a multi-week rodent study. Histological assessments indicated successful tissue integration for the sponges, and this material format responded more quickly to various oxygen challenges than the film samples.

Impact of iodine loading and substitution position on intersystem crossing efficiency in a series of ten methylated-meso-phenyl-BODIPY dyes

Four core and six distyryl-extended methylated-meso-phenyl-BODIPY dyes with varying iodine content were synthesized. The influence of iodine loading and substitution position on the photophysical properties of these chromophores was evaluated. Selective iodine insertion at the 2- and 6-positions of the methylated-meso-phenyl-BODIPY core, rather than maximum iodine content, resulted in the highest intersystem crossing efficiency. Iodination of the distyryl-extended BODIPY core afforded intersystem crossing quantum yields comparable to 2,6-diiodo-BODIPY. Inclusion of an iodine at the para-meso-phenyl position generally enhanced non-radiative decay in the BODIPY excited-state, leading to lower fluorescence and intersystem crossing quantum yield values. Iodine substitution at the styryl-positions resulted in negligible changes to the excited-state dynamics. This study highlights: (1) the rate of radiative decay is similar in all ten derivatives (on the order of 1 × 108 s-1), (2) iodination of the 2,6-positions results in the greatest enhancement of intersystem crossing efficiency, (3) care must be taken when modifying the para-meso-phenyl position as it could have detrimental effects on the excited-state dynamics, (4) the excited-state is negligibly affected by iodination of the styryl groups, potentially enabling orthogonal functionalization without modifying the molecular photophysics, (5) distyryl extension of the chromophore core diminishes rates of non-radiative decay and intersystem crossing, resulting in higher fluorescence quantum yields and lower intersystem crossing yields in the π-extended derivatives compared to the core BDP derivatives, and (6) DFT calculations provide insight into the electronic and structural factors regulating intersystem crossing and vibrational relaxation in these molecules.

Tandem Solar Cells from Accessible Low Band-Gap Polymers Using an Efficient Interconnecting Layer

Tandem solar cell architectures are designed to improve device photoresponse by enabling the capture of wider range of solar spectrum as compared to single-junction device. However, the practical realization of this concept in bulk-heterojunction polymer systems requires the judicious design of a transparent interconnecting layer compatible with both polymers. Moreover, the polymers selected should be readily synthesized at large scale (>1 kg) and high performance. In this work, we demonstrate a novel tandem polymer solar cell that combines low band gap poly isoindigo [P(T3-iI)-2], which is easily synthesized in kilogram quantities, with a novel Cr/MoO3 interconnecting layer. Cr/MoO3 is shown to be greater than 80% transparent above 375 nm and an efficient interconnecting layer for P(T3-iI)-2 and PCDTBT, leading to 6% power conversion efficiencies under AM 1.5G illumination. These results serve to extend the range of interconnecting layer materials for tandem cell fabrication by establishing, for the first time, that a thin, evaporated layer of Cr/MoO3 can work as an effective interconnecting layer in a tandem polymer solar cells made with scalable photoactive materials.

Steric hindrance inhibits excited-state relaxation and lowers the extent of intramolecular charge transfer in two-photon absorbing dyes

Steric hindrance inhibits excited-state relaxation and intramolecular charge-transfer, which significantly alters the photophysical properties.

Off-Resonant Two-Photon Absorption Cross-Section Enhancement of an Organic Chromophore on Gold Nanorods

Surface-plasmon-initiated interference effects of polyelectrolyte-coated gold nanorods on the two-photon absorption of an organic chromophore were investigated. With polyelectrolyte bearing gold nanorods of 2,4,6 and 8 layers, the role of the plasmonic fields as function of distance on such effects was examined. An unusual distance dependence was found: enhancements in the two-photon cross-section were at a minimum at an intermediate distance, then rose again at a further distance. The observed values of enhancement were compared to theoretical predictions using finite element analysis and showed good agreementdue to constructive and destructive interference effects.

Plasmonic enhancement of the two photon absorption cross section of an organic chromophore using polyelectrolyte-coated gold nanorods

The effect of plasmonic enhancement on the two-photon absorption cross section of organic chromophores attached to polyelectrolyte-coated gold nanorods was investigated. The magnitudes of such enhancements were confirmed using single and two photon excitations of the chromophore molecules bound to polyelectrolyte-coated gold nanorods. By synthesizing two-, four-, six-, and eight-polyelectrolyte layer coated nanorods of a particular aspect ratio, the distance dependence of the evanescent electromagnetic field on molecular two-photon absorption was observed. Enhancements of 40-fold were observed for the chromophores nearest to the surface.

Formation of high molecular weight complexes of mutant Cu, Zn-superoxide dismutase in a mouse model for familial amyotrophic lateral sclerosis

Deposition of aggregated protein into neurofilament-rich cytoplasmic inclusion bodies is a common cytopathological feature of neurodegenerative disease. How-or indeed whether-protein aggregation and inclusion body formation cause neurotoxicity are presently unknown. Here, we show that the capacity of superoxide dismutase (SOD) to aggregate into biochemically distinct, high molecular weight, insoluble protein complexes (IPCs) is a gain of function associated with mutations linked to autosomal dominant familial amyotrophic lateral sclerosis. SOD IPCs are detectable in spinal cord extracts from transgenic mice expressing mutant SOD several months before inclusion bodies and motor neuron pathology are apparent. Sequestration of mutant SOD into cytoplasmic inclusion bodies resembling aggresomes requires retrograde transport on microtubules. These data indicate that aggregation and inclusion body formation are mechanistically and temporally distinct processes.

Imaging manifestations of cat-scratch disease

Cat-scratch disease affects an estimated 22,000 people in the United States each year, more than half of whom are children or adolescents [1]. It is caused by Bartonella henselae, a gram-negative bacillus usually introduced by the scratch of a cat [2]. In the past, diagnosis was made if three of the following four criteria were met: (1) history of cat exposure with inoculation, (2) positive skin test: (3) absent laboratory and histopathologic evidence of other diseases, and (4) biopsy findings of granulomatous inflammation [3]. Recent identification of the causative organism has led to new diagnostic tests, including serum assays for B. henselae antibodies [4]. Although response of the disease to antibiotics is poor, spontaneous recovery generally occurs within months to years [3].

Oral melanoma: case reports and review of the literature

Oral melanomas occur most often on the palate and gingiva with the maxillary arch affected 80% of the time. Melanosis may exist many years before a definitive biopsy. Long-standing lesions may ulcerate but lack rolled borders or induration, features commonly associated with squamous cell carcinoma. Melanoma that involves oral mucosa is rare with an extremely poor prognosis. Surgical management remains the preferred treatment in combination with chemotherapy. Irradiation therapy is used occasionally as a primary modality in the elderly and medically compromised patients. Lymph node dissection is not routinely practiced. The poor prognosis of oral melanomas requires that pigmented lesions of undetermined origin be routinely biopsied.

Evaluation of the magnitude of the 1993 hantavirus outbreak in the southwestern United States

In May 1993, an outbreak of hantavirus pulmonary syndrome (HPS) in the southwestern United States was caused by the previously unrecognized Sin Nombre virus (SNV). Most HPS patients had an influenza-like prodrome, followed by rapid onset of pulmonary edema (fatality rate, 52%). To define the magnitude of the outbreak, patients with milder illnesses who sought medical care in the outbreak area during the outbreak period were assessed for infection with SNV. Of 299 study subjects, 43 had illnesses similar to the HPS prodrome. One laboratory finding, thrombocytopenia, was highly discriminatory between non-HPS patients (1%) and confirmed HPS patients (71%; P < .001) during the prodrome phase. No study subject had serologic evidence (IgM antibodies) of recent SNV infection. Five had IgG titers consistent with a previous hantavirus infection: 3 of these 5 were among the 43 patients who had illnesses similar to the HPS prodrome (P < .05). These data provide evidence that mild illness is rarely caused by SNV.

Use of Bartonella antigens for serologic diagnosis of cat-scratch disease at a national referral center

BACKGROUND

Bartonella henselae (formerly the genus Rochalimaea) has recently been isolated from patients with cat-scratch disease and their cats, and since September 1992 the Centers for Disease Control and Prevention has offered an indirect fluorescent antibody assay for Bartonella-specific antibody.

METHODS

Physicians submitted serum samples from patients suspected of having cat-scratch disease or other Bartonella-associated illness and completed a questionnaire that recorded clinical information. Indirect fluorescent antibody assay was performed with the use of antigen derived from three Bartonella species: B henselae, Bartonella quintana, and Bartonella elizabethae.

RESULTS

During 16 months, 3088 serum samples were received. The largest numbers of specimens and the highest percentages positive (titer, > or = 64) were observed in the fall and winter. Clinical histories of the first 600 patients for whom serum samples and completed information forms were received were examined in detail; seropositivity was significantly associated with cat contact, cat age of less than 1 year, cat scratch, presence of an inoculation papule, and regional adenopathy. Of 91 patients whose illness met a strict clinical definition of cat-scratch disease, 86 (95%) had titers of 64 or greater to either B henselae or B quintana. A fourfold rise or fall in titer was observed in 87 of 132 patients with paired serum samples.

CONCLUSIONS

The indirect fluorescent antibody assay for Bartonella-specific antibody is sensitive for the diagnosis of cat-scratch disease. Redefinition of cat-scratch disease on the basis of cause and use of this assay as a diagnostic criterion is recommended.

National surveillance for Rocky Mountain spotted fever, 1981-1992: epidemiologic summary and evaluation of risk factors for fatal outcome

Between 1981 and 1992, the Centers for Disease Control collected and summarized 9,223 cases of Rocky Mountain spotted fever (RMSF) reported from 46 states. Four states (North Carolina, Oklahoma, Tennessee, and South Carolina) accounted for 48% of the reports. The annual incidence per million U.S. population decreased from a high in 1981 of 5.2 to a low in 1992 of 2.0, primarily due to decreased incidence in the southeast. Case report forms were filed on 7,650 patients, of whom 4,217 had laboratory-confirmed RMSF. The age group with the highest incidence was those 5-9 years of age. Most cases (90.0%) occurred between April 1 and September 30 and included a history of tick attachment (59.6%). Reported symptoms included fever (94.0%), headache (86.2%), myalgia (82.5%), and rash (80.2%). The case-fatality ratio was 4.0%. Risk factors associated with death included older age, delay in treatment or no treatment, and treatment with chloramphenicol (compared with tetracycline); however, insufficient data existed to fully assess the confounding effect of severity of illness on antibiotic choice.

Kinetic effects of multiple oral doses of acetaminophen on a single oral dose of lamotrigine

In this double-blind, randomized, crossover, placebo-controlled study, the effect of multiple oral doses of acetaminophen on lamotrigine disposition was examined in healthy volunteers. Eight volunteers received two single 300 mg oral doses of lamotrigine, administered 20 days apart. Acetaminophen (2.7 gm/day) or placebo was taken for 24 hours before and continued for 10 days after each lamotrigine dose. Area under the plasma concentration-time curve for lamotrigine [AUC(O-infinity)] and lamotrigine half-life were statistically decreased by 20% (229.0 +/- 62.5 micrograms.hr/ml versus 191.2 +/- 42.1 micrograms.hr/ml, p less than 0.01) and 15% (35.7 +/- 9.3 hours versus 30.2 +/- 7.3 hours, p less than 0.01), respectively, when concurrently administered with acetaminophen. There was no significant difference in the peak plasma concentration or the time to reach peak plasma concentration. The percentage of the dose of lamotrigine recovered in the urine (total) was significantly higher during the acetaminophen treatment (65.9% +/- 12.3% versus 72.5% +/- 5.7%, p = 0.048). Acetaminophen seems to facilitate lamotrigine removal through a yet to be determined mechanism(s).

Characteristics of pyridoxine overdose neuropathy syndrome

A newly recognised neurotoxic syndrome due to pyridoxine (B6) overdose is described. It is the largest series of B6 intoxication hitherto reported. A raised serum B6 level was present in 172 women of whom 60% had neurological symptoms, which disappeared when B6 was withdrawn and reappeared in 4 cases when B6 was restarted. The mean dose of B6 in the 103 women with neurological symptoms was 117 +/- 92 mgs, compared with 116.2 +/- 66 mgs in the control group. There was a significant difference (P less than 0.01) in the average duration of ingestion of B6 in the neurotoxic group of 2.9 +/- 1.9 years compared with 1.6 +/- 2.1 years in controls. The symptoms were paraesthesia, hyperaesthesia, bone pains, muscle weakness, numbness and fasciculation, most marked on the extremities and predominantly bilateral unless there was a history of previous trauma to the limb. These women were taking a lower dose of B6 than previously described (1,2), which may account for the complete recovery within 6 months of stopping B6.

Cimetidine and carbamazepine: a complex drug interaction

Cimetidine has been shown to inhibit the elimination of carbamazepine after a single oral dose. The mechanism of this interaction is thought to be inhibition of carbamazepine metabolism by the hepatic microsomal enzyme system. Because carbamazepine metabolism undergoes autoinduction with chronic administration, it is not known whether or not the clinical significance of this interaction can be predicted from the results of a single-dose study. The purpose of this study was to evaluate the presence of an interaction under steady-state enzyme-induced conditions. Using an open treatment design, carbamazepine, 300 mg b.i.d., was taken by eight healthy volunteers for 42 days (days 1-42). Cimetidine, 400 mg t.i.d., was taken for 7 days (days 29-35). Steady-state carbamazepine increased 17% after 2 days of cimetidine treatment (from 4.7 +/- 0.8 to 5.5 +/- 1.4 micrograms/ml; p less than 0.05). Six of the eight subjects noted side effects shortly after starting cimetidine treatment. Carbamazepine returned to the pre-cimetidine level and the side effects diminished by the 7th day of cimetidine administration. Therefore, the clinical significance of this interaction appears to be time dependent, and could not be predicted from the results of single-dose studies.

Ranitidine does not alter single-dose carbamazepine pharmacokinetics in healthy adults

In our recent study, oral cimetidine increased carbamazepine plasma levels after a single oral dose by 26 percent and prolonged the elimination half-life by 18 percent. This effect of cimetidine on carbamazepine could have resulted from enhanced carbamazepine absorption and/or inhibited metabolism. To gain an insight into which mechanism was responsible, we repeated the study with ranitidine, which has nearly identical gastrointestinal effects as cimetidine, but does not inhibit oxidative metabolism. Eight healthy subjects received a single dose of carbamazepine 600 mg po on two occasions separated by one month. In a randomized sequence, they also received ranitidine 300 mg/d or matching placebo starting two days before and continuing until seven days after the carbamazepine dose. Ranitidine did not change the carbamazepine area under the plasma concentration-time curve (324.2 +/- 71.1 micrograms h/ml, placebo vs. 326.3 +/- 65.0 micrograms h/ml, ranitidine; p = 0.84) or the elimination half-life (32.2 +/- 6.4 h, placebo vs. 31.7 +/- 6.1 h, ranitidine; p = 0.62). Since ranitidine does not alter the pharmacokinetic profile of oral carbamazepine, it is unlikely that the changes observed with cimetidine were due to increased carbamazepine absorption. Therefore, the mechanism of the single-dose carbamazepine-cimetidine interaction is probably metabolic inhibition, although the exact pathway (or pathways) affected has not been identified.

The influence of cimetidine on single-dose carbamazepine pharmacokinetics

The purpose of this study was to evaluate the influence of cimetidine on carbamazepine pharmacokinetics in healthy adults, since carbamazepine toxicity in a patient has been attributed to an interaction with cimetidine and in vitro and in vivo studies in rats have shown that cimetidine inhibits carbamazepine metabolism. Eight healthy volunteers received a single 600-mg oral dose of carbamazepine on two occasions, separated by 1 month. In a randomized crossover sequence, cimetidine 1,200 mg/day or placebo was taken for 48 h before and continuing for 7 days after each carbamazepine dose. Plasma concentrations of carbamazepine and carbamazepine-10,11-epoxide and urine concentrations of carbamazepine, the 10,11-epoxide, and the transdiol metabolite were measured in samples collected for 154 h following each carbamazepine dose. Cimetidine treatment was associated with increases of 26 and 18% in carbamazepine area under the concentration-time curve (AUC) and elimination half-life, respectively. There was also an increase in carbamazepine-10,11-epoxide AUC (27%) and t 1/2 (12%) during cimetidine treatment. There was no difference in the ratio of the 10,11-epoxide to the carbamazepine AUC between treatments. The urinary excretion (expressed as molar percentage of the administered dose) of carbamazepine, 10,11-epoxide, and transdiol metabolite all increased with cimetidine. Although cimetidine appears to inhibit carbamazepine elimination based on the increased elimination half-life, the effect must be on carbamazepine metabolic pathways that we could not measure and that account for greater than 80% of the administered dose. The clinical significance of this interaction should be verified under steady-state conditions when carbamazepine autoinduction is present.

Consultative total parenteral nutrition teams: the effect on the incidence of total parenteral nutrition-related complications

A two part, prospective study was undertaken to establish the existing frequency of total parenteral nutrition-(TPN) related mechanical, metabolic, and septic complications in an institution with a consultative TPN team (group A) and to determine if increasing the involvement of the TPN team in patient monitoring and verifying adherence to TPN infection control guidelines would reduce the incidence of these complications (group B). The initial 28 consecutive patients were managed entirely by their primary physicians with the role of the TPN team limited to consultative activities while the next 29 patients receiving TPN were managed jointly by their primary physicians and the TPN team. Analysis of the results show group B to have a significant reduction in metabolic complications, decreased incidence of mechanical abnormalities, and approximately equal incidences of documented sepsis. However, when compared to the results of an institution in which the TPN team has complete control of TPN therapy, even the group B patients had a relatively excessive number of TPN-related complications especially in the categories of mechanical and metabolic abnormalities. Thus, consultative TPN teams do not necessarily ensure optimum TPN therapy and institutions using this approach to provide nutrition parenterally must be prepared to establish the incidence of TPN-related complications and to expand the involvement of the TPN team as required to control the frequency of these anomalies.