Photodynamic Therapy in Pigmented Basal Cell Carcinoma-A Review

This review summarizes the effectiveness of photodynamic therapy (PDT) in the treatment of the pigmented subtype of basal cell carcinoma (BCC) based on the current literature. PDT is a light-activated treatment, non-invasive, that selectively destroys tumor cells and tissues via the interaction of a photosensitizer, light, and molecular oxygen. It can induce cancer cell death through direct tumor vascular damage or via the induction of immune response. However, human skin is also an absorption and scattering medium since it contains hemoglobin and melanin that act as chromophores. Eumelanin can be considered a light-absorber and an intracellular antioxidant that can neutralize PDT-induced ROS and, therefore, decrease PDT success. Various factors, including tumor depth, the degree of pigmentation in malignant cells, and the individual's skin phototype, can impact the outcome of this intricate biochemical process. It has been widely recognized that PDT exhibits limited efficacy in the treatment of pigmented lesions. However, new combination techniques such as curettage or debulking before PDT show promising results in the treatment of pigmented BCC.

Pathomechanism of Pruritus in Psoriasis and Atopic Dermatitis: Novel Approaches, Similarities and Differences

Pruritus is defined as an unpleasant sensation that elicits a desire to scratch. Nearly a third of the world's population may suffer from pruritus during their lifetime. This symptom is widely observed in numerous inflammatory skin diseases-e.g., approximately 70-90% of patients with psoriasis and almost every patient with atopic dermatitis suffer from pruritus. Although the pathogenesis of atopic dermatitis and psoriasis is different, the complex intricacies between several biochemical mediators, enzymes, and pathways seem to play a crucial role in both conditions. Despite the high prevalence of pruritus in the general population, the pathogenesis of this symptom in various conditions remains elusive. This review aims to summarize current knowledge about the pathogenesis of pruritus in psoriasis and atopic dermatitis. Each molecule involved in the pruritic pathway would merit a separate chapter or even an entire book, however, in the current review we have concentrated on some reports which we found crucial in the understanding of pruritus. However, the pathomechanism of pruritus is an extremely complex and intricate process. Moreover, many of these signaling pathways are currently undergoing detailed analysis or are still unexplained. As a result, it is currently difficult to take an objective view of how far we have come in elucidating the pathogenesis of pruritus in the described diseases. Nevertheless, considerable progress has been made in recent years.

Characteristics of pruritus in various clinical variants of psoriasis: Final report of the binational, multicentre, cross-sectional study

BACKGROUND

Pruritus, which is the most frequent subjective symptom of psoriasis, may cause significant discomfort, embarrassment and even interfere with patients normal daily activities. However, the perception of itch in various psoriasis subtypes remains unknown.

OBJECTIVES

The aim of this study was to investigate and to characterize pruritus in different clinical variants of psoriasis.

METHODS

This cross-sectional, binational, multicentre study included 295 subjects suffering from nine different clinical subtypes of psoriasis: large-plaque psoriasis (n = 45), nummular psoriasis (n = 32), guttate psoriasis (n = 31), scalp psoriasis (n = 32), inverse psoriasis (n = 23), erythrodermic psoriasis (n = 33), palmoplantar psoriasis vulgaris (n = 33), palmoplantar pustular psoriasis (n = 42) and generalized pustular psoriasis (n = 23). Measures included sociodemographic and anthropometric data, detailed pruritus characteristics including but not limited to pruritus intensity, frequency and extend, as well as psoriasis severity.

RESULTS

The lifetime prevalence of pruritus in each clinical variant of psoriasis was similar and quite high, reaching up to 100% in some disease subtypes (i.e., nummular psoriasis, scalp psoriasis and generalized pustular psoriasis). Psoriasis severity correlated with pruritus intensity in scalp psoriasis, palmoplantar pustular psoriasis and generalized pustular psoriasis. The age, duration of psoriasis and BMI did not interfere with the intensity of itch.

CONCLUSIONS

Pruritus is highly prevalent in each clinical variant of psoriasis. However, the sensation of itch is very individual, difficult to universally describe even in the same subtype.

YY1 Is a Key Player in Melanoma Immunotherapy/Targeted Treatment Resistance

Malignant melanoma, with its increasing incidence and high potential to form metastases, is one of the most aggressive types of skin malignancies responsible for a significant number of deaths worldwide. However, melanoma also demonstrates a high potential for induction of a specific adaptive anti-tumor immune response being one of the most immunogenic malignancies. Yin Yang 1 (YY1) transcription factor is essential to numerous cellular processes and the regulation of transcriptional and posttranslational modifications of various genes. It regulates programmed cell death 1 (PD1) and lymphocyte-activation gene 3 (LAG3) by binding to its promoters, as well as suppresses both Fas and TRAIL by negatively regulating DR5 transcription and expression and interaction with the silencer region of the Fas promoter, rendering cells resistant to apoptosis. Moreover, YY1 is considered a master regulator in various stages of embryogenesis, especially in neural crest stem cells (NCSCs) survival and proliferation as it acts as transcriptional repressor on cancer stem cells-related transcription factors. In addition, YY1 increases the metastatic potential of melanoma through negative regulation of microRNA-9 (miR-9) expression, acts as a cofactor of transcription factor EB (TFEB) and contributes to autophagy regulation, mainly due to increased transcription of genes related to autophagy and lysosome biogenesis. Therefore, focusing on the detailed biology and administration of therapies that directly target YY1 or crosstalk pathways in malignant melanoma could facilitate the development of new and more effective treatment strategies and improve patients’ outcomes.

Novel photoinitiators based on difluoroborate complexes of squaraine dyes for radical polymerization of acrylates upon visible light

The present article describes the efficiency of novel two-component photoinitiators based on a typical squaraine dye and its difluoroborate analogues for the radical polymerization of acrylate monomers.

Role of Mast Cells in the Pathogenesis of Pruritus in Mastocytosis

Pruritus can be defined as an unpleasant sensation that evokes a desire to scratch and significantly impairs patients' quality of life. Pruritus is widely observed in many dermatoses, including mastocytosis, a rare disease characterized by abnormal accumulation of mast cells, which can involve skin, bone marrow, and other organs. Increasing evidence highlights the role of mast cells in neurogenic inflammation and itching. Mast cells release various pruritogenic mediators, initiating subsequent mutual communication with specific nociceptors on sensory nerve fibres. Among important mediators released by mast cells that induce pruritus, one can distinguish histamine, serotonin, proteases, as well as various cytokines. During neuronal-induced inflammation, mast cells may respond to numerous mediators, including neuropeptides, such as substance P, neurokinin A, calcitonin gene-related peptide, endothelin 1, and nerve growth factor. Currently, treatment of pruritus in mastocytosis is focused on alleviating the effects of mediators secreted by mast cells. However, a deeper understanding of the intricacies of the neurobiology of this disease could help to provide better treatment options for patients.

Characteristics of Pruritus in Various Clinical Variants of Psoriasis: Results of the Multinational, Multicenter, Cross-Sectional Study

Psoriasis is a chronic, inflammatory skin disease present in about 3% of the world’s population. The clinical symptoms manifest diversely, therefore one can distinguish several subtypes of psoriasis. The majority of patients with psoriasis experience pruritus, which is an unpleasant sensation that decreases patients’ quality of life. The knowledge on pruritus in different subtypes of psoriasis is limited. We have performed a cross-sectional, prospective, and multicenter study to evaluate the relationship between clinical subtypes of psoriasis (large-plaque, nummular, guttate, palmoplantar, inverse, erythrodermic, palmoplantar pustular, generalized pustular psoriasis, and psoriasis of the scalp) and the prevalence, intensity, and clinical manifestation of itch. We introduced a questionnaire assessing various aspects of pruritus to a total of 254 patients. Out of these, 42 were excluded. Pruritus was present in 92.9% of the remaining patients and its prevalence did not depend on the clinical subtype. A correlation between the severity of psoriasis and the intensity of itch was explicitly noticeable in palmoplantar pustular psoriasis and scalp psoriasis (p < 0.05). The itch sensation was individual and differed among subtypes of psoriasis. In conclusion, pruritus is a frequent phenomenon, and its presentation is different in various subtypes of psoriasis.

Novel Photoreactive Pressure-Sensitive Adhesives (PSA) Based on Acrylics Containing Additionable Photoinitiators

A new class of additionable ultraviolet photoinitiators that can be used, through addition, for modification of the acrylic polymer chain and their influence of main properties of acrylic pressure-sensitive adhesives (PSAs) is described here. The photoinitiators studied are based on benzophenone, dibenzofuran and anthraquinone chromophores. The propyleneimine carbonyl is the reactive additionable group incorporated in the photoinitiator structure. First, the solvent-borne acrylic pressure-sensitive adhesive was synthesized and characterized. Then, a photoinitiator suitable for addition to the acrylic polymer chain possessing a carboxyl group was added before UV-irradiation. A mechanism of UV-initiated cross-linking reaction of acrylic PSA with additionable photoinitiators was done as well. The influence of the concentration and type of photoinitiator, UV-crosslinking time and UV-dose on peel adhesion, shear strength and tack of solvent-borne acrylic pressure-sensitive adhesives cross-linked by UV light was studied and presented here. It was found that the tack depends on the UV-dose and photoinitiator concentration. An increase of UV dose results in an increase of shear strength of acrylic pressure-sensitive adhesive (PSA) formulations.

Influence of an Alkoxylation Grade of Acrylates on Shrinkage of UV-Curable Compositions

Commercially available UV curable restorative materials are composed of inorganic filler hydroxyapatite, multifunctional methacrylate, photoinitiator and alkoxylated acrylate. Especially, the application of alkoxylated monomers with different alkoxylation grade allows the reduction of polymerization shrinkage which plays the major role by application of low shrinkage composites as high quality restorative dental materials or other adhesive materials in the form of UV-polymerized self-adhesive acrylics layers (films). There are several ways to reduce polymerization shrinkage of restorative compositions, for example, by adjusting different alkoxylated acrylic monomers, which are integral part of investigated UV curable restorative composites. This article is focused on the studies of contraction-stress measured as shrinkage during UV-initiated curing of restorative composites containing various commercially available alkoxylated acrylates. Moreover, studies with experimental restorative materials and recent developments typical for UV curing technology using special photoreactive monomers are described.

Onium salts improve the kinetics of photopolymerization of acrylate activated with visible light

The aim was study the influence of onium salts on the kinetics of photopolymerization in the visible light region. Trimethylolpropane triacrylate TMPTA was selected as a monomer, and activated by 1,3-bis(phenylamino)squaraine (SQ) used as a photosensitizer in addition to tetramethylammonium n-butyltriphenylborate (B2). The iodonium salt [A–I–B]⁺X⁻ functioned as a second radical initiator, bearing a different substitution pattern for the cation. The ternary system was formulated with different concentrations of both borate and diphenyliodonium salts. Differential scanning calorimetry was used to investigate the polymerization reaction over the photoactivation time carried out at 300 nm < λ < 500 nm irradiation. When the squaraine dye/borate salt was used as photoinitiator, a slow polymerization reaction was observed and a lower monomer conversion. The addition of a third component (onium salt) increased the polymerization rate and conversion. Ternary photoinitiator systems showed improvement in the polymerization rate of triacrylate leading to high conversion in a short photoactivation time. The photoinitiating ability of bi- and tri-component photoinitiators acting in the UV-Vis region for initiation polymerization of triacrylate was compared with those of some commercially used photoinitiating systems. It was also found, that, the parallel electron transfer from an excited state of the sensitizer to [A–I–B]⁺X⁻, and an electron transfer from a ground state of R(Ph)₃B⁻N(CH₃)₄⁺ to an excited state of the sensitizer results in two types of initiating radical.

The chemical mechanisms were investigated by steady state photolysis and nanosecond laser flash photolysis experiments. A mechanism for initiating polymerization using both onium salts is proposed here.

Landscape of current and future therapies of Merkel cell carcinoma

Merkel cell carcinoma is rare and aggressive skin cancer, which occurrence is linked to exposure to ultraviolet light and the Merkel-cell polyomavirus. In recent years, significant progress in understanding the mechanism of Merkel cell carcinoma pathogenesis has been observed. This neoplasm often expresses PD-L1, and MCPyV-specific T cells can express PD-1 thus PD-1/PD-L1 checkpoint therapies seem to be remarkably interesting treatment options. Many clinical trials are currently being conducted to confirm their effectiveness and safety for this group of patients. However, only about half of advanced Merkel cell carcinoma patients could achieve remission or disease stabilization through PD-1/PD-L1 checkpoint therapies thus innovative treatments are still needed. In this article, we have presented current and future directions in the development of Merkel cell carcinoma therapy.

Highly efficient UV-Vis light activated three-component photoinitiators composed of tris(trimethylsilyl)silane for polymerization of acrylates

The goal of this paper concerns the evaluation of the efficiency of novel three-component systems for initiating the photopolymerization process of 2-ethyl-2-(hydroxymethyl)-1,3-propanediol triacrylate (TMPTA).

Delusions of Parasitosis: An Update

Delusional parasitosis, also known as delusional infestation or Ekbom syndrome, is a relatively infrequent psychotic disorder characterized by an unwavering false belief that there is a parasitic infestation of the skin, despite the absence of any medical evidence that could support this claim. Delusional parasitosis can be categorized into primary, secondary, and organic forms. Sometimes, close relatives also experience identical delusions. This phenomenon was reported to occur in 5-15% of cases, and is known as shared psychotic disorder-delusional parasitosis with folie à deux. Patients with delusional parasitosis frequently seek help from many physicians. Close multidisciplinary cooperation between clinicians is often key to shortening the time taken to diagnose this disorder. Initiation of psychopharmacological therapy is a challenge, as many patients refuse any psychiatric treatment because of the stigma associated with mental illness and because of their firm belief that they have a parasitic infestation, not a psychiatric condition. For many patients, a sense of a lack of understanding leads to isolation and the development of depression symptoms, which is why it is crucial to earn the trust of such patients while taking care of them.

Beyond PD-1 Immunotherapy in Malignant Melanoma

For many years, the standard therapy for malignant melanoma was based mainly on surgical resection. Unfortunately, this treatment is curative only in the early localized stage of this malignancy. The metastatic stage of malignant melanoma still remains a huge therapeutic challenge. Despite the many new therapeutic options that have become available over the last years, there is a constant need for safer and more effective treatment modalities. There has been a dynamic development of various anti-cancer immunotherapies directed against new molecular targets. A number of clinical trials are currently being conducted to confirm their effectiveness and safety. In this review of the literature, we summarize the contemporary knowledge on promising new immunotherapies beyond the currently available treatment options for malignant melanoma, including oncolytic immunotherapy, selective inhibitors of indoleamine 2,3-dioxygenease, anti-PD-(L)1 (programmed death ligand 1) drugs, immune checkpoint protein LAG-3 antibodies, inhibitors of histone deacetylase (HDAC) and inhibitors of B7-H3.

The uefa euro 2012 anti-doping programme - scientific review

The final tournament of the UEFA European Football Championship is one of the top sporting events in the world, and a high-profile event of this kind requires a well-planned and well-executed anti-doping programme to ensure the integrity of results in the competition. UEFA EURO 2012 presented a unique logistical challenge, with the tournament spread across two countries, both covering a large geographical area. This paper discusses the planning and delivery of both the pre tournament out-of-competition (OOC) testing programme and the in-competition (IC) programme, as well as reviewing the activities of doping control officers (DCOs), the whereabouts programme and assessing the sample collection and transport process. The analytical approach applied is also discussed, along with an overview of the distribution of T/E ratios and blood parameters.

Identification and characterization of urinary prenylamine metabolites by means of liquid chromatography-tandem mass spectrometry

Prenylamine is a vasodilator of phenylalkylamine structure and was used for the treatment of angina pectoris, until reports of undesirable effects including ventricular tachycardia led to a decreasing use of the drug in the 1980s. Metabolic N-dealkylation of orally ingested prenylamine can liberate amphetamine in humans and cause positive findings for amphetamine in doping and forensic analysis. In 2010, the World Anti-Doping Agency (WADA) classified prenylamine as a non-specified stimulant according to the 2010 Prohibited List, thus banning its use in sports in-competition. Supporting the development of a liquid chromatography-tandem mass spectrometry (LC-MS/MS) based detection method, a post-administration urine sample following a single oral prenylamine ingestion (Segontin(®) 60 mg) was analyzed for urinary metabolites. The LC-separated analytes were ionized in positive electrospray ionization (ESI) mode and detected as protonated ions using an AB Sciex TripleTOF 5600 quadrupole-time-of-flight hybrid mass spectrometer. Over 40 phase I metabolites were detected, including previously unknown mono- bis-, tris- and tetra-hydroxylated prenylamine, several hydroxylated and methoxylated prenylamine metabolites and (hydroxylated) diphenylpropylamine. Investigation of the collision-induced dissociation behaviours of the metabolites by high resolution/high accuracy mass spectrometry allowed for the assignment of the nature and the site of observed metabolic transformations. The most abundant phase I metabolite was confirmed as p-hydroxy-prenlyamine by chemical synthesis and stable isotope labelling of reference material. An existing routine screening assay based on direct injection and LC-MS/MS analysis of urine was modified and validated according to common guidelines, in order to allow for the detection of p-hydroxy-prenylamine in sports drug testing. The assay demonstrated the ability to detect the target metabolite at 0.1 ng/ml at intra- and inter-day imprecisions below 10%.

The effect of endotoxin administration on cytokine production in obstructive jaundiced rats

The aim of this study was to evaluate the effect of lipopolysaccharide (LPS) administration, which mimics a surgical intervention, on the immune status of obstructive jaundiced (OJ) and sham-operated control rats. Rats were given 20 microgram LPS intraperitoneally on day 13 following bile duct ligation or sham surgery. We determined serum levels of tumor necrosis factor alpha (TNF-alpha) and interleukin 6 (IL-6) on day 14 after surgery, and spontaneous as well as LPS-induced production of these cytokines in splenocyte and peritoneal exudate cell (PEC) cultures. We found that IL-6, but not TNF-alpha, serum concentrations were significantly elevated (4-fold) in OJ rats treated with LPS compared with LPS-untreated OJ rats. In sham-operated rats the differences between the respective groups were not significant. The production of TNF-alpha by splenocyte and PEC cultures was depressed in OJ rats treated with LPS; in particular, a very deep decline was observed in the case of spontaneous TNF-alpha production in PEC cultures. In contrast, TNF-alpha production in LPS-untreated and LPS-treated sham-operated rats did not differ. In the case of IL-6 production by splenocytes and PEC cultures, we observed a significant suppression of this cellular function in both OJ and sham-operated rats treated with LPS when compared with the respective controls. In conclusion, the results indicate that the already depressed cytokine production in OJ rats leads to even deeper hyporeactivity following LPS challenge. Lack of TNF-alpha suppression upon LPS treatment in sham-operated rats suggests that surgery-elicited hyporeactivity is mediated by a different mechanism than that leading to immune hyporesponsiveness in OJ. Our findings may explain the relatively high mortality rates observed of OJ patients subjected to surgery.

The impairment of wound healing process is correlated with abnormalities of TNF-alpha production by peritoneal exudate cells in obstructive jaundiced rats

The wound healing process and production of tumour necrosis factor alpha (TNF-alpha) by peritoneal cells of 7-day and 14-day obstructive jaundice (OJ) and sham-operated rats were investigated. In the study the skin wound breaking strength was measured. In addition such histological and biochemical parameters as fibroblast and endothelial cell proliferation, inflammatory cell infiltration and hydroxyproline content were evaluated in polyurethane sponge discs implanted subcutaneously into rats. TNF-alpha production by peritoneal exudate cells (PEC), both spontaneous and lipopolysaccharide (LPS)-induced was determined by a bioassay. In OJ rats the process of both early as well as late phase of healing was impaired. The breaking strength of skin wound was decreased, the fibroblast and endothelial cell proliferation and collagen deposition, as well as hydroxyproline content were diminished. In 7 day OJ the numbers of inflammatory cells in the implants were lowered with a subsequent slight increase on day 14 of OJ. The spontaneous and LPS induced TNF-alpha production by PEC were significantly higher in 7 day OJ as compared with sham-operated controls. On day 14 of OJ the LPS-induced TNF-alpha level was, in contrast, much lower and did not differ much from the spontaneous TNF-alpha production. We conclude that the impairment of wound healing in OJ results from disturbances in functioning of the immune system caused by systemic endotoxaemia.

[Adhesive glycoproteins of the extracellular matrix]

Glycoproteins of the extracellular matrix and basement membrane play crucial role in cell recognition, adhesion, migration and proliferation. Morphogenesis and tissue and organ development in embryo, as well as healing processes in adults are dependent on the interactions of extracellular proteins with cell surface receptors. In this paper the structure and function of major adhesive proteins: fibronectin, tenascin, laminin and nidogen are reviewed. Recent data on the role of small leucine-rich and modular proteoglycans, such as decorin, biglycan, fibromodulin, versican, perlecan, neurocan, agrecan, agrin and other are given. Modifications of the expression and localization of extracellular glycoproteins in pathology are also presented.

Platinum complexes and pyruvate kinase activity

The interaction of platinum complexes with bovine heart pyruvate kinase (PK) was studied by absorption, CD, fluorescence spectroscopy and enzymic activity test. Our results showed that activity of PK was reduced by cis-DDP and potassium tetrachloroplatinate in a time-and concentration dependent manner. Cis-DDP was less effective than K2PtCl4 in reducing PK activity. The native enzyme showed well defined negative Cotton effect at 222 and 208 nm indicating the presence of alpha-helical and beta structure. Platinum binding lowered the Cotton effect in this region by about 10-20% and 30-50% for the system with cis-DDP and K2PtCl4, respectively. Fluorescence study showed that platinum binding quenched tryptophan fluorescence suggesting that binding occurs at the tryptophan residue or its proximity. PK modifications induced by platinum binding would result in a greater resistance to denaturing agents.

[Metabolism of nicotine--mechanism and clinical effects of toxicity]

Nicotine is a major constituent of tobacco and exerts a number of physiological effects. Metabolism of nicotine in animal and human tissues is reviewed. Clinical considerations regarding the problems of toxic effects of nicotine in human and molecular basis of carcinogen mechanism of nicotine derivatives are discussed.

Structure and expression of the cDNA for the C isozyme of phosphofructo-1-kinase from rabbit brain

Rabbit brain contains three phosphofructo-1-kinase (PFK) isozymic subunits designated A, B, and C. The primary structures of the first of these two isozyme types have been determined previously. The isozyme C of rabbit brain was isolated by immunoaffinity chromatography and subjected to proteolytic and chemical digestion. A large number of peptides were sequenced, the total number of amino acids identified being equal to about 80% of the total structure. The sequence of the cDNA derived from brain mRNA for C isozyme was determined from polymerase chain reaction fragments synthesized using oligonucleotides designed on the basis of the peptide sequences. The deduced size of the C isozyme was 86,371 Da, slightly larger than PFKs described previously. The amino acid sequence identity with the rabbit A isozyme was 68.9% and a range of identity to other sequenced mammalian PFKs was 67-69%. Using these data plus previously published data on chemical modification, assignments of the 6 organic ligand binding sites of PFK were inferred. The full-length cDNA was cloned into and expressed in Escherichia coli. Phosphofructokinase C was purified to homogeneity from the bacterial extracts.

[Surgical treatment of ventricular tachycardia in patients with post-infarction aneurysms]

4 patients (P) with recurrent, sustained ventricular tachycardia (VT) resistant to medical treatment, underwent surgery for cure of this arrhythmia. Each P had episodes of VT lasting 30 or more seconds, 3 of them had episodes of ventricular fibrillation. In all cases rhythm disturbances were secondary to post myocardial infarction aneurysm. Coronary angiography showed in all P total occlusion of LAD, in 2 cases significant lesion in RCA were found. 1 P had lung cancer. All P underwent aneurysmectomy and an excision of the altered endocardium by Harken's method. The endocardial excision was performed without endocardial mapping. 2 P had concomitant CABG to RCA. In the P with lung cancer lobectomy was performed. There were 2 ++non-arrhythmic death. The P with lung cancer died because of sepsis due to lung abscess. One P died because of heart failure (preoperative EF 10%), 6 months after the surgery. The 2 survivors remained free of VT during a follow-up period 8 months. In conclusion, endocardial excision by Harken's method is efficient in treating recurrent sustained VT, resistant to medical treatment, in patients with post myocardial infarction aneurysm. The surgical procedure can be performed without intraoperative endocardial mapping.

The sites of phosphorylation of rabbit brain phosphofructo-1-kinase by cyclic AMP-dependent protein kinase

The three isozymic subunits of phosphofructo-1-kinase present in rabbit brain and designated A, B and C were phosphorylated in vitro by cyclic AMP-dependent protein kinase with 32P-labeled ATP. Limited digestion of the labeled enzymes with trypsin or with Staphylococcus aureus V8 proteinase led to the solubilization of radiolabeled peptides derived from the three isozymic subunits. Limited digestion by V8 proteinase was accompanied by a slight reduction in the apparent sizes of the subunits, indicating that the phosphorylated sites are located near either the amino or carboxyl termini of the protein. V8 proteinase digestion led to no change in the maximal activity of the enzyme but did abolish sensitivity to ATP inhibition. The phosphopeptides of the tryptic and the V8 digests were purified by chromatography and their amino acid sequences were determined and compared to the previously established sequence from rabbit muscle isozyme A. PFK-A E H I S R K R S G E A T V PFK-B H V T R R S L S M A K G F PFK-C V S A S P R G S Y R K F L In each instance, the phosphorylated serine, underlined in the above sequences, was found to be one or two residues toward the C-terminus of one or more basic residues. No other similarities in structure were noted.

Identification of the AMP binding sites of rabbit phosphofructo-1-kinase isozymes B and C

Rabbit liver phosphofructo-1-kinase, designated isozyme B, and rabbit brain phosphofructokinase, which contains all three isozymes as heteropolymers, have been modified by [14C]fluorosulfonylbenzoyladenosine (FSBAdo). Several lines of evidence supported modification at the binding site for AMP. The modification proceeded to the extent of 2 to 4 mol of reagent incorporated per mol of tetramer, and AMP protected against the reaction. The kinetic properties of modified isozymes A and B and of modified brain phosphofructokinase were examined and compared to their unmodified forms. It was observed that modification greatly diminished ATP inhibition of all of the isozymes. Furthermore, equilibrium binding studies of modified phosphofructokinase B showed a greatly diminished capacity and affinity for cyclic AMP. Cyclic AMP had little or no influence on the properties of modified A isozyme or brain phosphofructokinase, but was capable of further deinhibiting modified B isozyme, apparently at sites remaining unmodified by FSBAdo. Phosphofructokinase B, modified by radiolabeled FSBAdo, was digested by trypsin, and the digest separated by high-pressure liquid chromatography. The labeled peptide was isolated and sequenced to provide the sequence: Asn-Tyr-Gly-Thr-Lys-Leu-Gly-Val-Lys, with the lysine in the fifth position being the site of modification. To isolate isozyme C, a monoclonal antibody to this isozyme was produced by injecting purified rabbit brain phosphofructokinase into mice, and subsequently selecting for those clones that recognized brain phosphofructokinase but not purified phosphofructokinases A and B. The selected monoclonal was specific for native rabbit isozyme C and would not recognize mouse or rat brain phosphofructokinases. Linking the antibody to an inert phase provided an efficient means of purifying rabbit isozyme C from rabbit brain. The enzyme so recovered retained little of its original activity, but the method provided a simple technique for the preparation of enzyme for protein chemistry studies. The modified C isozyme was isolated on the immuno-affinity column and digested with trypsin. A tryptic peptide bearing the label was isolated and sequenced to provide the structure: Asn-Phe-Gly-Thr-Lys-Ile-Ser-Ala-Arg, with position 5 being the site of modification. The sequences of isozymes B and C are homologous to the site of modification of the A isozyme by FSBAdo.

Phosphofructokinase in the rat nervous system: regional differences in activity and characteristics of axonal transport

The distribution of phosphofructokinase (PFK) in gray and white matter regions of the rat nervous system was evaluated. Determinations of PFK activity revealed that cell body enriched regions (sensorimotor cortex) had a significantly higher level of activity than axonal regions (sciatic nerve, dorsal roots, and optic nerve). The level of PFK activity was also significantly higher in central axons (optic nerve) than in peripheral axons (sciatic nerve). Differences in PFK activity could be largely attributed to differences in tissue content of the enzyme rather than to differences in the types of PFK isozymes present. Cortex contained significantly larger amounts of PFK relative to total protein than did peripheral nerve. However, purification of PFK revealed that all three of the PFK isozymes, C (86 kd), A (84 kd), and B (80 kd), were present in both cortex and sciatic nerve. Both SDS/PAGE and immunoblotting studies using PFK isozyme-specific antibodies demonstrated that the relative proportions of the three PFK isozymes were similar in cell body and axonal regions of the nervous system. The PFK-C and PFK-A isozymes each comprised about half the total and only small amounts of the PFK-B isozyme were present in both regions. However, immunoprecipitation experiments suggested that quantitatively different proportions of the possible PFK hybrids (tetramers) may be distributed between axonal and cell body regions. The transport of PFK was examined in this study and PFK was identified in slow component b (SCb) of axonal transport. SCb moves at a rate of 2-4 mm/day in rat axons and is known to contain several other enzymes of intermediary metabolism as well as actin. The finding that PFK, the rate limiting enzyme in glycolysis, is present in SCb lends support to the hypothesis that glycolytic enzymes are not freely diffusing proteins in axons but, instead, are present as organized assemblies that have long-term, yet flexible, associations with structural elements of the cytoplasm.

Inorganic pyrophosphate: fructose-6-phosphate 1-phosphotransferase of the potato tuber is related to the major ATP-dependent phosphofructokinase of E. coli

A procedure was developed for the purification of inorganic pyrophosphate: fructose-6-phosphate 1-phospho-transferase (PPi-PFK) from potato tubers. The enzyme has the structure alpha 4 beta 4 with a subunit of 68 kDa and a beta subunit of 60 kDa. The structural relationship of this enzyme to other PFKs and to fructose bisphosphatase was examined by immunoprecipitation and immunoblotting. Antibodies to the plant enzyme did not react with E. coli PFK. No cross-reaction was seen among the following enzymes or their antibodies: yeast fructose bisphosphatase; rabbit PFKs A, B, or the enzyme from brain; and the two subunits of the potato PPi-PFK. On the other hand, antibody to E. coli PFK-1 strongly cross-reacts with the 60 kDa polypeptide but not 68 kDa peptide.

Acquired enzymopathy of erythrocyte glucose-6-phosphate dehydrogenase in acute viral hepatitis

Erythrocyte glucose-6-phosphate dehydrogenase from patients with acute viral hepatitis has been purified and characterized. The enzyme showed decreased activity (relative to protein), reduced affinity for glucose 6-phosphate and was inactivated at 45 degrees C or at low pH values. The activity and properties of normal erythrocyte enzyme, incubated in vitro with blood plasma of patients, showed a similar pattern of modifications. Incubation with bilirubin affected the enzyme stability, but not its activity or affinity for substrate.