Quality of Life with Neutrophilic Dermatoses

Neutrophilic dermatoses (NDs) encompass a wide range of cutaneous and extracutaneous manifestations, many of which impair quality of life (QoL) and are difficult to treat. Although NDs are transient and mild, others are chronic, severely debilitating conditions with profound impacts on QoL, including pain, mental health, occupational limitations, and sexual health implications. Current literature lacks attention to these unique care challenges to the ND patient population. The authors aim to summarize what is currently known about QoL in NDs and identify which diseases would benefit from additional research and disease-specific QoL assessment.

Smaller hospital discharge volume and urban area are associated with higher proportional cellulitis discharges

Cellulitis is commonly misdiagnosed, resulting in increased healthcare costs and complications. There is little published work regarding the relationship between hospital characteristics and cellulitis discharge rates. Here, we performed a cross-sectional analysis of cellulitis inpatient discharges using publicly available national data to examine hospital characteristics associated with higher proportional cellulitis discharge rates. The results of our study showed a strong association of increased proportion of cellulitis discharges in association with hospitals that discharged fewer total patients and a direct association with urban location. The factors that influence hospital cellulitis discharge diagnoses are numerous, and while its overdiagnosis remains a source of medical overspending and complications, our study may provide direction for more focused efforts to increase dermatology care in lower volume hospitals and urban areas.

Detection of novel therapies using a multi-national, multi-institutional registry of cutaneous immune-related adverse events and management

BACKGROUND

Cutaneous immune-related adverse events (cirAEs) remain a prevalent and common sequelae of immune checkpoint inhibitor (ICI) therapy, often necessitating treatment interruption and prolonged immune suppression. Treatment algorithms are still poorly defined, based on single-institution case reports without adequate safety assessments, and subject to publication bias.

METHODS

Data in this registry were collected through a standardized REDCap form distributed to dermatologists via email listserv.

RESULTS

Ninety-seven cirAEs were reported from 13 institutions in this registry. Topical and systemic steroids were the most common treatments used; however, targeted treatment matched to disease morphology was identified at numerous sites. Novel cirAE therapy uses that to our knowledge have not been previously described were captured including tacrolimus for the treatment of follicular, bullous, and eczematous eruptions and phototherapy for eczematous eruptions. Moreover, further evidence of cirAE treatment applications sparsely described in literature were also captured in this study including dupilumab and rituximab for bullous eruptions, phototherapy for lichenoid and psoriasiform eruptions, and acitretin for psoriasiform eruptions, among others. No serious adverse events were reported. Numerous targeted therapeutics including dupilumab, rituximab, and psoriasis biologics, among others, were associated with a cirAE grade improvement of ≥2 grades in every patient treated.

CONCLUSION

This study suggests that a multi-institutional registry of cirAEs and management is not only feasible but that the information collected can be used to detect, evaluate, and rigorously assess targeted treatments for cirAEs. Further expansion and modification to include treatment progression may allow for sufficient data for specific treatment recommendations to be made.

NIH research funding success in dermatology training programs, a cross-sectional analysis

Training programs with strong research funding are crucial to academic dermatology and are essential to the development of future dermatology researchers. While previous studies have examined the influence of individual investigator characteristics on funding success, no studies to our knowledge have examined the influence of dermatology training program characteristics on successful receipt of NIH funding. Here, we used publicly available data regarding NIH funding and dermatology training programs to understand the factor influencing successful NIH funding. The results of our study showed strong associations of funding success with the strength of the associated college of medicine, as well as an association with programs having departmental status vs. divisional status. The factors that influence successful funding are multiple, and while many factors cannot be changed or mitigated, our study may provide support to programs who have yet to achieve departmental status.

Novel and Off-Label Biologic Use in the Management of Hidradenitis Suppurativa, Pyoderma Gangrenosum, Lichen Planus, and Seborrheic Dermatitis: A Narrative Review

With advances in drug development and our understanding of the pathophysiology of skin disease, biologic medications have emerged as powerful management tools for dermatologists. While biologics have most often been used in the management of psoriasis, they are being used off-label for the management of a variety of other immune-mediated skin diseases with overlapping molecular targets. This narrative review focuses on the novel and off-label use of biologic medications for the management of hidradenitis suppurativa (HS), pyoderma gangrenosum (PG), lichen planus (LP), and seborrheic dermatitis (SD). Review of the literature revealed that IL-17, IL-23, and tumor necrosis factor (TNF) inhibitors were being used across a variety of immune-mediated skin pathologies with variable efficacy, among other targeted biologics. While biologics were generally safe in the treatment of primary immune-mediated skin disorders, paradoxical disease eruptions were noted with biologic use and were theorized to occur owing to immune dysregulation and cytokine imbalance. While numerous case reports show promise for the use of biologics in immune-mediated skin pathologies, the variable efficacy and safety reported warrants more thorough investigations of the role of these targeted medications in comprehensive disease management.

US emergency department visits for acute harms from over-the-counter cough and cold medications, 2017-2019

BACKGROUND AND PURPOSE

Characterization of emergency department (ED) visits for acute harms related to use of over-the-counter cough and cold medications (CCMs) by patient demographics, intent of CCM use, concurrent substance use, and clinical manifestations can help guide prevention of medication harms.

METHODS

Public health surveillance data from the National Electronic Injury Surveillance System-Cooperative Adverse Drug Event Surveillance project were used to estimate numbers and population rates of ED visits from 2017 to 2019.

RESULTS

Based on 1396 surveillance cases, there were an estimated 26 735 (95% CI, 21 679-31 791) US ED visits for CCM-related harms annually, accounting for 1.3% (95% CI, 1.2-1.5%) of all ED visits for medication adverse events. Three fifths (61.4%, 95% CI, 55.6-67.2%) of these visits were attributed to non-therapeutic CCM use (nonmedical use, self-harm, unsupervised pediatric exposures). Most visits by children aged <4 years (74.0%, 95% CI, 59.7-88.3%) were for unsupervised CCM exposures. Proportion hospitalized was higher for visits for self-harm (76.5%, 95% CI, 68.9-84.2%) than for visits for nonmedical use (30.3%, 95% CI, 21.1-39.6%) and therapeutic use (8.8%, 95% CI, 5.9-11.8%). Overall, estimated population rates of ED visits for CCM-related harms were higher for patients aged 12-34 years (16.5 per 100 000, 95% CI, 13.0-20.0) compared with patients aged <12 years (5.1 per 100 000, 95% CI, 3.6-6.5) and ≥ 35 years (4.3 per 100 000, 95% CI, 3.4-5.1). Concurrent use of other medications, illicit drugs, or alcohol was frequent in ED visits for nonmedical use (61.3%) and self-harm (75.9%).

CONCLUSIONS

Continued national surveillance of CCM-related harms can assess progress toward safer use.

Enhancing membrane repair increases regeneration in a sciatic injury model

Various injuries to the neural tissues can cause irreversible damage to multiple functions of the nervous system ranging from motor control to cognitive function. The limited treatment options available for patients have led to extensive interest in studying the mechanisms of neuronal regeneration and recovery from injury. Since many neurons are terminally differentiated, by increasing cell survival following injury it may be possible to minimize the impact of these injuries and provide translational potential for treatment of neuronal diseases. While several cell types are known to survive injury through plasma membrane repair mechanisms, there has been little investigation of membrane repair in neurons and even fewer efforts to target membrane repair as a therapy in neurons. Studies from our laboratory group and others demonstrated that mitsugumin 53 (MG53), a muscle-enriched tripartite motif (TRIM) family protein also known as TRIM72, is an essential component of the cell membrane repair machinery in skeletal muscle. Interestingly, recombinant human MG53 (rhMG53) can be applied exogenously to increase membrane repair capacity both in vitro and in vivo. Increasing the membrane repair capacity of neurons could potentially minimize the death of these cells and affect the progression of various neuronal diseases. In this study we assess the therapeutic potential of rhMG53 to increase membrane repair in cultured neurons and in an in vivo mouse model of neurotrauma. We found that a robust repair response exists in various neuronal cells and that rhMG53 can increase neuronal membrane repair both in vitro and in vivo. These findings provide direct evidence of conserved membrane repair responses in neurons and that these repair mechanisms can be targeted as a potential therapeutic approach for neuronal injury.

Automated logic synthesis for electro-optic logic-based integrated optical computing

Integrated optical computing attracts increasing interest recently as Moore's law approaches the physical limitation. Among all the approaches of integrated optical computing, directed logic that takes the full advantage of integrated photonics and electronics has received lots of investigation since its first introduction in 2007. Meanwhile, as integrated photonics matures, it has become critical to develop automated methods for synthesizing optical devices for large-scale optical designs. In this paper, we propose a general electro-optic (EO) logic in a higher level to explore its potential in integrated computing. Compared to the directed logic, the EO logic leads to a briefer design with shorter optical paths and fewer components. Then a comprehensive gate library based on EO logic is summarized. At last, an And-Inverter Graphs (AIGs) based automated logic synthesis algorithm is described as an example to implement the EO logic, which offers an instruction for the design automation of high-speed integrated optical computing circuits.

Antioxidant network expression abrogates oxidative posttranslational modifications in mice

Antioxidant enzymatic pathways form a critical network that detoxifies ROS in response to myocardial stress or injury. Genetic alteration of the expression levels of individual enzymes has yielded mixed results with regard to attenuating in vivo myocardial ischemia-reperfusion injury, an extreme oxidative stress. We hypothesized that overexpression of an antioxidant network (AON) composed of SOD1, SOD3, and glutathione peroxidase (GSHPx)-1 would reduce myocardial ischemia-reperfusion injury by limiting ROS-mediated lipid peroxidation and oxidative posttranslational modification (OPTM) of proteins. Both ex vivo and in vivo myocardial ischemia models were used to evaluate the effect of AON expression. After ischemia-reperfusion injury, infarct size was significantly reduced both ex vivo and in vivo, ROS formation, measured by dihydroethidium staining, was markedly decreased, ROS-mediated lipid peroxidation, measured by malondialdehyde production, was significantly limited, and OPTM of total myocardial proteins, including fatty acid-binding protein and sarco(endo)plasmic reticulum Ca(²+)-ATPase (SERCA)2a, was markedly reduced in AON mice, which overexpress SOD1, SOD3, and GSHPx-1, compared with wild-type mice. These data demonstrate that concomitant SOD1, SOD3, and GSHPX-1 expression confers marked protection against myocardial ischemia-reperfusion injury, reducing ROS, ROS-mediated lipid peroxidation, and OPTM of critical cardiac proteins, including cardiac fatty acid-binding protein and SERCA2a.

A NF-kappa B/Sp1 region is essential for chromatin remodeling and correct transcription of a human granulocyte-macrophage colony-stimulating factor transgene

The GM-CSF gene is expressed following activation of T cells. The proximal promoter and an upstream enhancer have previously been characterized using transfection and reporter assays in T cell lines in culture. A 10.5-kb transgene containing the entire human GM-CSF gene has also been shown to display inducible, position-independent, copy number-dependent transcription in mouse splenocytes. To determine the role of individual promoter elements in transgene function, mutations were introduced into the proximal promoter and activity assessed following the generation of transgenic mice. Of four mutations introduced into the transgene promoter, only one, in an NF-kappaB/Sp1 region, led to decreased induction of the transgene in splenocytes or bone marrow-derived macrophages. This mutation also affected the activity of reporter gene constructs stably transfected into T cell lines in culture, but not when transiently transfected into the same cell lines. The mutation alters the NF-kappaB family members that bind to the NF-kappaB site as well as reducing the binding of Sp1 to an adjacent element. A DNase I hypersensitive site that is normally generated at the promoter following T cell activation on the wild-type transgene does not appear in the mutant transgene. These results suggest that the NF-kappaB/Sp1 region plays a critical role in chromatin remodeling and transcription on the GM-CSF promoter in primary T cells.

Pediatric asthma quality of life questionnaire: validation in children from Singapore

"Quality of Life" is a multidimensional measure encompassing the physical, emotional and social functioning of the child. The asthma specific questionnaire contains 23 questions (items) in three areas (domains) of activity, symptoms and emotions. The objective of the present study was to validate the Paediatric Asthma Quality of Life Questionnaire "PAQLQ"(copyright 1991 McMaster University). If the questionnaire is valid, a change in the child's asthma will be accompanied by a change in the "Quality of Life" questionnaire score. The questionnaire was administered twice over four weeks and the child's asthma status was assessed concurrently. Two groups were thus identified; Group A = unchanged asthma, Group B = changed asthma. Forty-seven children, aged 7 to 14 years, completed the study. Reliability of the questionnaire shows an intraclass-correlation coefficient of only 0.71. Cross-sectional construct validity was demonstrated by a significant correlation between the whole questionnaire and the clinical asthma score (p<0.001) but not in the separate domains. Longitudinal construct validity was also demonstrated by the significant correlation between change in the total questionnaire score, but not separate domains, with change in the child's asthma score (p<0.05). Responsiveness was shown by a significant difference in the magnitude of the change in the questionnaire score between the two groups (p<0.001), but again not in the separate domains. It was concluded that the questionnaire was validated as a whole but not in as convincing a manner, as has been done by others, and we are therefore in a position to advise caution in its application in our population.

The single CH domain of calponin is neither sufficient nor necessary for F-actin binding

Calponins have been implicated in the regulation of actomyosin interactions in smooth muscle cells, cytoskeletal organisation in nonmuscle cells, and the control of neurite outgrowth. Domains homologous to the amino-terminal region of calponin have been identified in a variety of actin cross-linking proteins and signal transduction molecules, and by inference these 'calponin homology (CH) domains' have been assumed to participate in actin binding. We here report on the actin binding activities of the subdomains of the calponin molecule. All three mammalian isoforms of calponin (basic h1, neutral h2 and acidic) possess a single CH domain at their amino terminus as well as three tandem repeats proximal to the carboxyl terminus. Calponin h2 differs, however, from h1 in lacking a consensus actin-binding motif in the region 142-163, between the CH domain and the tandem repeats, which in h1 calponin can be chemically cross-linked to actin. Despite the absence of this consensus actin-binding motif, recombinant full-length h2 calponin co-sediments in vitro with F-actin, suggesting the presence of another binding site in the molecule. It could be shown that this binding site resides in the C-terminal tandem repeats and not in the CH domain. Thus, constructs of h2 calponin bearing partial or complete deletions of the triple repeated sequences failed to co-localise with actin stress fibres despite the presence of a CH domain. Deletion of the acidic carboxyl terminus, beyond the repeats, increased actin binding, suggesting that the carboxy-terminal tail may modulate actin association. Results obtained from transient transfections of amino- and carboxy-terminal truncations in h1 calponin were consistent with the established location of the actin binding motif outside and carboxy-terminal to the CH domain, and confirm that the presence of a single CH domain alone is neither sufficient nor necessary to mediate actin binding. Instead, the carboxy-terminal tandem repeats of h1 and h2 calponin are shown to harbour a second, independent actin binding motif.

Simian virus 40 large T antigen interacts with human TFIIB-related factor and small nuclear RNA-activating protein complex for transcriptional activation of TATA-containing polymerase III promoters

The TATA-binding protein (TBP) is common to the basal transcription factors of all three RNA polymerases, being associated with polymerase-specific TBP-associated factors (TAFs). Simian virus 40 large T antigen has previously been shown to interact with the TBP-TAFII complexes, TFIID (B. Damania and J. C. Alwine, Genes Dev. 10:1369-1381, 1996), and the TBP-TAFI complex, SL1 (W. Zhai, J. Tuan, and L. Comai, Genes Dev. 11: 1605-1617, 1997), and in both cases these interactions are critical for transcriptional activation. We show a similar mechanism for activation of the class 3 polymerase III (pol III) promoter for the U6 RNA gene. Large T antigen can activate this promoter, which contains a TATA box and an upstream proximal sequence element but cannot activate the TATA-less, intragenic VAI promoter (a class 2, pol III promoter). Mutants of large T antigen that cannot activate pol II promoters also fail to activate the U6 promoter. We provide evidence that large T antigen can interact with the TBP-containing pol III transcription factor human TFIIB-related factor (hBRF), as well as with at least two of the three TAFs in the pol III-specific small nuclear RNA-activating protein complex (SNAPc). In addition, we demonstrate that large T antigen can cofractionate and coimmunoprecipitate with the hBRF-containing complex TFIIIB derived from HeLa cells infected with a recombinant adenovirus which expresses large T antigen. Hence, similar to its function with pol I and pol II promoters, large T antigen interacts with TBP-containing, basal pol III transcription factors and appears to perform a TAF-like function.

Mechanistic analysis of RNA polymerase III regulation by the retinoblastoma protein

The tumour suppressor protein RB restricts cellular growth. This may involve inhibiting the synthesis of tRNA and 5S rRNA by RNA polymerase (pol) III. We have shown previously that RB can repress pol III transcription when overexpressed either in vitro or in vivo. We also demonstrated that pol III activity is elevated substantially in primary fibroblasts from RB-deficient mice. Here we address the molecular mechanism of this regulation. RB is shown to repress all types of pol III promoter. It can do this even if added after transcription complex assembly. Functional assays demonstrate that RB targets specifically the general pol III factor TFIIIB. A physical interaction between TFIIIB and RB is indicated by fractionation, pull-down and immunoprecipitation data. We show that TFIIIB activity is elevated in primary fibroblasts from RB-deficient mice. TFIIIB is a multisubunit complex that includes the TATA-binding protein (TBP) and a TFIIB-related factor called BRF. We show that RB itself contains regions of homology to both TBP and BRF and propose a model in which RB disrupts TFIIIB by mimicking these two components.

RNA polymerase III transcription from the human U6 and adenovirus type 2 VAI promoters has different requirements for human BRF, a subunit of human TFIIIB

Mammalian TFIIIB can be separated into two fractions required for transcription of the adenovirus type 2 VAI gene, which have been designated 0.38M-TFIIIB and 0.48M-TFIIIB. While 0.48M-TFIIIB has not been characterized, 0.38M-TFIIIB corresponds to a TBP-containing complex. We describe here the purification of this complex, which consists of TBP and a closely associated polypeptide of 88 kDa, and the isolation of a cDNA corresponding to the 88-kDa polypeptide. The predicted protein sequence reveals that the 88-kDa polypeptide corresponds to a human homolog of the Saccharomyces cerevisiae BRF protein, a subunit of yeast TFIIIB. Human BRF (hBRF) probably corresponds to TFIIIB90, a protein previously cloned by Wang and Roeder (Proc. Natl. Acad. Sci. USA 92:7026-7030, 1995), although its predicted amino acid sequence differs from that reported for TFIIIB90 over a stretch of 67 amino acids as a result of frameshifts. Immunodepletion of more than 90 to 95% of the hBRF present in a transcription extract severely debilitates transcription from the tRNA-type VAI promoter but does not affect transcription from the TATA box-containing human U6 promoter, suggesting that the 0.38M-TFIIIB complex, and perhaps hBRF as well, is not required for U6 transcription.

Detection of UV-induced RNA:protein crosslinks in snRNPs by oligonucleotides complementary to the snRNA

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Biochemical demonstration of complex formation of histone pre-mRNA with U7 small nuclear ribonucleoprotein and hairpin binding factors

Histone RNA 3' end formation occurs through a specific cleavage reaction that requires, among other things, base-pairing interactions between a conserved spacer element in the pre-mRNA and the minor U7 snRNA present as U7 snRNP. An oligonucleotide complementary to the first 16 nucleotides of U7 RNA can be used to characterize U7 snRNPs from nuclear extracts by native gel electrophoresis. Using similar native gel techniques, we present direct biochemical evidence for a stable association between histone pre-mRNA and U7 snRNPs. Other complexes formed in the nuclear extract are dependent on the 5' cap structure and on the conserved hairpin element of histone pre-mRNA, respectively. However, in contrast to the U7-specific complex, their formation is not required for processing. Comparison of several authentic and mutant histone pre-mRNAs with different spacer sequences demonstrates that the formation and stability of the U7-specific complex closely follows the predicted stability of the potential RNA-RNA hybrid. However, this does not exclude a stabilization of the complex by U7 snRNP structural proteins.

The effect of some new platinum (II) and palladium (II) coordination complexes on rat hepatic nuclear transcription in vitro

Several new L-amino acid derivatives of 2,2'-bipyridine and 1,10-phenanthroline complexes of platinum (Pt) and palladium (Pd) and a few binuclear 2,2'-bipyridine complexes of these metals were tested for their potential to inhibit rat hepatic nuclear transcription in vitro. Pd complexes were generally more effective inhibitors of transcription than the corresponding Pt complexes. Among Pd-diimine chlorides, the 2,2'-bipyridine complex was nearly 10 times more active than the corresponding 1,10-phenanthroline complex. Both Pt-diimine chlorides, however, showed same level of inhibitory activity. Amino acid derivatives were less inhibitory with respect to the parent metal diimine chlorides except for 1,10-phenanthroline complexes of Pd. For binuclear 2,2'-bipyridine complexes of Pt, the increase in length of linking hydrocarcon chain increased the inhibitory potential of the complex. The mechanism of inhibition of transcription by these metal complexes was sought to be understood by use of actinomycin-D and poly[d(I-C)] to differentiate effect on the two major components of transcription machinery viz. the template and the enzyme. These studies along with studies on reconstituted system of transcription using either pretreated template or enzyme indicate that these metal complexes displayed dual effect on transcription by inhibiting both the template and the enzymes.

Synthesis, characterization, and cytotoxic studies of alpha-diimine/1,2-diamine platinum(II) and palladium(II) complexes of selenite and tellurite and binding of some of these complexes to DNA

Eleven new complexes of formula [M(NN)(XO3)] (where M is Pd(II) or Pt(II); NN is 2,2'-bipyridine, 1,10-phenanthroline, 2,2'-dipyridylamine, ethylenediamine or (+-)trans-1,2-diaminocyclohexane, and XO3(2-) is SeO3(2-) or TeO3(2-)) have been synthesized. These water soluble complexes have been characterized by chemical analysis and conductivity measurements as well as ultraviolet-visible and infrared spectroscopy. In these complexes the selenite or tellurite ligand coordinates to platinum(II) or palladium(II) as bidentate with two oxygen atoms. These complexes inhibit the growth of P 388 lymphocytic leukemia cells, their targets are DNA. The selenite complexes invariably show I.D.50 values less than cisplatin. However, the I.D.50 values of the tellurite complexes are usually higher than cisplatin, except that of [Pd(dach)(TeO3)] which has comparable I.D.50 values, as compared to cisplatin. [Pt(bipy)(SeO3)] and [Pd(bipy)(SeO3)] have been interacted with calf thymus DNA and bind to DNA through a coordinate covalent bond.

Synthesis, characterization, DNA binding, and cytotoxic studies of some mixed-ligand palladium(II) and platinum(II) complexes of alpha-diimine and amino acids

The syntheses of nine palladium(II) complexes of type [Pd(phen)(AA)]+ (where AA is an anion of glycine, L-alanine, L-leucine, L-phenylalanine, L-tyrosine, L-tryptophan, L-valine, L-proline, or L-serine) have been achieved. These palladium(II) complexes have been characterized by ultraviolet-visible, infrared, and 1H NMR spectroscopy. The binding studies of several complexes [M(NN)(AA)]+ (where M is Pd(II) as Pt(II), NN is 2,2'-bipyridine or 1,10-phenanthrodine, and AA is an anion of amino acid) with calf thymus DNA have been carried out using UV difference absorption and fluorescence spectroscopy. The mode of binding of the above complexes to DNA suggests the involvement of the hydrogen bonding between them. Several complexes [M(phen)(AA)]+ (where M is Pd(II) or Pt(II) and AA is an anion of amino acid) have also been screened for cytotoxicity in P388 lymphocytic cells. Of them, only two complexes, [Pd(Phen)(Gly)]+ and [Pd(phen)(Val)]+, show comparable cytotoxicity, as cisplatin does.

Synthesis, characterization, and DNA binding studies of some mixed-ligand platinum(II) complexes of 1,10-phenanthroline and amino acids

A series of complexes of the type [Pt(phen)(AA)]+ (where AA is the anion of glycine, L-alanine, L-leucine, L-phenylalanine, L-tyrosine, or L-tryptophan) has been synthesized. These complexes have been characterized by electronic absorption, infrared, and 1H NMR spectroscopy. The interaction of these complexes with calf thymus DNA has been studied using fluorescence spectroscopy. They inhibit the intercalation of ethidium bromide in DNA by intercalative binding at low concentrations and show nonintercalative binding at higher concentrations.

Synthesis, spectroscopic, mutagenic, and cytotoxicity studies of some mixed-ligand platinum(II) complexes of 2,2'-bipyridine and amino acids

Seven platinum(II) complexes of the type [Pt(bipy)(AA)]n+ (where n = 1 or 0 and AA is anion of L-valine, L-isoleucine, L-aspartic acid (dianion), L-glutamic acid (dianion), L-glutamine, L-proline, or S-methyl-L-cysteine) have been prepared and characterized. The modes of binding of amino acids in these complexes have been ascertained particularly by infrared and 1H NMR spectral studies. The L-glutamine complex shows a ID50 value (50% inhibitory dose) in the range of greater than 20 micrograms/ml to 100 micrograms/ml of the complex. However, the complexes of L-valine, L-isoleucine, L-aspartic acid, L-glutamic acid, L-proline, and S-methyl-L-cysteine show ID50 values greater than 100 micrograms/ml of the complex. The above complexes also show inferior growth inhibition of P-388 cells than platinum(II) complexes of 2,2'-bipyridine with L-alanine, L-leucine, L-methionine, and L-aspargine as reported earlier. The platinum(II) complexes of 2,2'-bipyridine with glycine (Gly), L-alanine (Ala), L-leucine (leu), L-valine (Val), L-methionine (Met), L-phenylalanine (Phe), L-serine (Ser), L-tyrosine (Tyr) and L-tryptophan (Trp) have been tested for mutagenesis using TA 100 and TA 98 strains. They show nonmutagenicity. This is in contrast to the cis-[Pt(NH3)2Cl2] showing a base pair substitution mutagenesis.

Study of binding of some amino acid derivatives of 2,2'-bipyridineplatinum(II) to calf thymus DNA

The interactions of glycine, alanine, valine, leucine, proline, methionine, and asparagine derivatives of 2,2'-bipyridineplatinum(II) with calf thymus DNA, polyadenylic acid, and polyguanylic acid have been studied by difference absorption spectral technique. The association constants (Kapp) and number of binding sites per 100 nucleotides (n) have been obtained from binding isotherms which were constructed by treatment of data according to Scatchard equation. The Kapp values (2.2 X 10(4) to 4.6 X 10(5) M-1) of binding of platinum complexes with DNA are comparable to Kapp values (5.6 X 10(4) to 2.9 X 10(5) M-1) of binding of platinum complexes with polyguanylic acid. However, the polyadenylic acid does not exhibit any binding to platinum complexes. The hydrogen bonding is, however, the most probable mode of bonding involved in stabilizing the DNA-amino acid complexes.