A comparative study of regulatory perspectives on innovative medical devices in Korea and the United States

INTRODUCTION

As the 4th Industrial Revolution era emerges, medical devices that apply technologies such as big data, artificial intelligence, and 3D printers are on the rise. In April 2019, Korea introduced the Act on Nurturing Medical Devices Industry and Supporting Innovative Medical Devices to shorten the market entry time by conducting step-by-step screening through the designation of innovative medical devices, priority screening systems, and special permission screening systems.

AREAS COVERED

In this study, the Breakthrough Device Program of the United States, which has been implemented since 2016, and Korea's innovative medical device designation system were compared.

EXPERT OPINION

Compared to the United States, Korea seems complicated because it has one more step in reviewing the innovative medical device group, but in terms of content, the two countries designate innovative medical devices on a similar basis. Neither country has established properly innovative medical device health insurance. Thus, a new insurance benefit scoring system based on actual evidence will have to be established. The role of experts in analyzing these data will be important and the voices of both innovative medical device manufacturers and medical field experts must be accepted.

Encephalopathy and seizure activity in a COVID-19 well controlled HIV patient

A 41-year-old male with a history of well controlled HIV presented with confusion and was found to have COVID-19. Lumbar puncture was negative. He had worsening encephalopathy with tonic-clonic seizure requiring intubation. He was treated with hydroxychloroquine and azithromycin with improvement in mental status back to baseline after 6 days.

Abstract P5-05-02: Regulation of glucose metabolism by the RUNX2 transcription factor has a negative impact on mitochondrial function in breast cancer cells

The RUNX2 transcription factor regulates breast cancer (BC) metastasis to bone and is itself a target of IGF-1 signaling pathways. We have shown that glucose can activate RUNX2 phopshorylation through IGF-1 receptor signaling and that RUNX2 was associated with inhibition of pyruvate dehydrogenase (PDHA1) activity and repression of mitochondrial respiration in BC cells. However, the mechanisms by which RUNX2 alters mitochondrial function and supports an oncogenic phenotype are not completely known. RUNX2 expression in a luminal BC cell line increased expression of glycolytic genes, and sensitivity to glucose starvation. However, RUNX2 knockdown in a triple-negative BC cell line inhibited expression of glycolytic genes. RUNX2 also repressed mitochondrial oxygen consumption rates (OCR), a measure of oxidative phosphorylation while overexpression of SIRT6, a NAD-dependent histone deacetylase, increased respiration in RUNX2-positive cells. RUNX2 repressed SIRT6 expression directly at the transcriptional and post-translational levels. High SIRT6 expression was observed in normal mammary tissue and cells that did not express RUNX2 but endogenous SIRT6 expression was low in malignant BC tissues or cell lines, which expressed high levels of RUNX2. These results suggest that SIRT6, a known tumor suppressor, was a critical mediator of these RUNX2-regulated metabolic changes. These results support a hypothesis whereby RUNX2 upregulation during BC progression leads to inactivation of the SIRT6 tumor suppressor to promote tumorigenesis. It will be important to investigate further changes in mitochondrial function to understand the precise mechanisms by which RUNX2 regulates BC metabolism.

Citation Format: Kim MS, Choe M, Cho H, Polster BM, Girnun GD, Passaniti A. Regulation of glucose metabolism by the RUNX2 transcription factor has a negative impact on mitochondrial function in breast cancer cells. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P5-05-02.

Fibroblast growth factor 21 analogue LY2405319 lowers blood glucose in streptozotocin-induced insulin-deficient diabetic mice by restoring brown adipose tissue function

AIM

To investigate the effects of LY2405319, an analogue of fibroblast growth factor 21 (FGF21), on glucose homeostasis in streptozotocin (STZ)-induced insulin-deficient mice (STZ mice).

METHODS

Nine-week-old male C57BL/6J mice were administered a single intraperitoneal injection of STZ (150 mg/kg). One week later, after confirmation of hyperglycaemia, saline or LY2405319 (5 mg/kg) was injected subcutaneously daily for 4 weeks. Changes in glucose homeostasis, energy metabolism and brown adipose tissue (BAT) function were assessed.

RESULTS

The STZ mice had elevated blood glucose and reduced plasma FGF21 levels, impaired glucose uptake in the BAT, and BAT mitochondria with absent or swollen cristae and fewer lipid vacuoles. LY2405319 significantly reduced blood glucose levels and this was associated with increased BAT glucose uptake and changes in gene expression and morphology, indicating improved mitochondrial lipid metabolism in the BAT. Importantly, the ability of LY2405319 to lower blood glucose in STZ mice was compromised after removing interscapular BAT.

CONCLUSIONS

Our results show that LY2405319 reduces blood glucose levels in insulin-deficient diabetes by improving BAT metabolism. Additional studies investigating the therapeutic potential of FGF21 for the treatment of type 1 diabetes are warranted.

Abstract P4-03-05: The Warburg Effect and RUNX2-Regulated Metabolic Switching in Breast Cancer: A New Therapeutic Target?

Breast cancer (BC) is the leading cause of cancer deaths among women in North America and Western Europe. Numerous studies have shown that breast tumor progression is associated with a switch from mitochondrial oxidative phosphorylation (OxPhos) to increased utilization of glucose and aerobic glycolysis (Warburg effect). Uncovering underlying mechanisms regulating this progression may lead to innovative approaches for treatment. The RUNX2 DNA-binding transcription factor is expressed in highly aggressive BC and regulates bone metastasis in animal models. We observed increased expression of RUNX2 in primary human ductal carcinoma in situ (DCIS), which correlated with grade and proliferative index (Ki67 staining), decreased estrogen receptor/progesterone receptor expression (ER/PR status), increased glucose uptake values by PET scanning, and increased expression of the glucose transporter, GLUT1. Further, more than 80% (9 out of 11) of triple-negative BC cell lines examined expressed RUNX2. Therefore, to test the hypothesis that RUNX2 may alter the metabolic status of breast cancers and increase their dependence on glycolysis during tumor progression, we have generated a Tet-OFF model system using MCF7 cells with inducible RUNX2 expression. RUNX2-positive MCF7 cells exhibited increased cell death under conditions of glucose depletion or when treated with 2-deoxy-glucose, a competitive inhibitor of hexokinase II. Conversely, RUNX2-positive cells were more resistant to OxPhos inhibitors (rotenone, oligomycin) than RUNX2-negative cells. We also observed higher expression levels of GLUT1 and pAKT in RUNX2-positive MCF7 cells. Hypoxia-inducible factor-α (HIF1α) is a transcription factor that regulates cancer metabolism through its activation of glycolytic genes, while SIRT6, an NAD-dependent deacetylase, is a negative regulator of HIF1α activity. This occurs, in part, via inhibition of HIF1α transcriptional activity. RUNX2-positive or negative cells expressed HIF1α in response to glucose but RUNX2-positive cells exhibited lower SIRT6 expression than RUNX2-negative cells, suggesting that with the loss of SIRT6, HIF1α might be more active in promoting glycolysis in the presence of RUNX2. These results suggest that RUNX2 may have clinical diagnostic value as an indicator of BC metabolic stress and predictor of poor prognosis. Current strategies are utilizing computer-assisted drug design to develop RUNX-specific inhibitors to target BC glycolysis and tumor growth.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P4-03-05.

A divalent recombinant immunotoxin formed by a disulfide bond between the extension peptide chains

Recombinant immunotoxin for the treatment of cancer was made by connecting toxins to 'carcinoma-specific' antibodies that selectively bind to cancer cells, then kills them without harming the normal cells. The divalent recombinant immunotoxin, [B3(Fab)-ext-PE38]2, is a derivative of B3(Fab)-PE38. B3(Fab)-PE38 was made by fusing the Fab domain of the monoclonal antibody (MAb) B3 to PE38, a truncated mutant form of Pseudomonas exotoxin (PE). In this study, B3(Fab)-ext-PE38 was constructed, which has the hinge region of the B3(Fab)-PE38 extended with the peptide extension, G4C(G4S)2, and connected to the C3 connector. The Cys residue of the extension peptide chain makes the disulfide bond between the two Fab domains. The extension sequence (ext) makes the dimerization of B3(Fab)-ext-PE38 easier to form the divalent immunotoxin, because it decreases the steric hindrance between the two PE38s. The constructed genes were expressed in E. coli as inclusion bodies. Polypeptides that were obtained from the inclusion body were refolded, and the active forms were purified. The ID50 values of the divalent molecule, [B3(Fab)-ext-PE38]2, were about 4 ng/ml on A431 cell lines, about 1 ng/ml on CRL1739 cell lines, and 5 ng/ml on MCF-7 cell lines. The [B3(Fab)-ext-PE38]2 showed about a 12-fold higher cytotoxicity on CRL1739 cell lines than B3(scFv)-PE40 did.

The proteins of synaptic vesicle membranes are affected during ageing of rat brain

Low molecular weight GTP-binding proteins are molecular switches that are believed to play pivotal roles in cell growth, differentiation, cytoskeletal organization, and vesicular trafficking. Rab proteins are key players in the regulation of vesicular transport, while Rho family members control actin-dependent cell functions, i.e. the regulation of cytoskeletal organization in response to extracelluar growth factors and in dendritic neuron development. In this study, we have examined the regulation of small GTP-binding proteins that are implicated in neurosecretion and differentiation of neuron during ageing processes. Comparison of small GTP-binding proteins from the synaptosome and crude synaptic vesicles (LP2 membranes) of 2 months and 20 months old rat brain respectively showed no difference in the level of Rab family proteins (Rab3A and Rab5A). However, Rho family proteins such as RhoA and Cdc42 were elevated in LP2 membranes of the aged brain. The dissociation of Rab3A by Ca2+/calmodulin (CaM) from SV membranes was not changed during aging. Ca2+/CaM stimulated phosphorylation of the 22 and 55-kDa proteins in SV membranes from the aged rat brain, and inhibited phosporylation of 30-kDa proteins. GTPgammaS inhibited phosphorylation of the 100-kDa proteins and stimulated phosphorylation of the 70 kDa in LP2 membranes from both the young and aged rat brains, whereas GDPbetaS caused just the opposite reaction. These results suggest that protein phosphorylation and regulation of Rho family GTPases in rat brain appears to be altered during ageing processes.

Random changes of amino acid residues with expected frequency by saturated point mutagenesis

The yeast transcriptional activator protein, Gcn4p from Saccharomyces cerevisiae binds to the specific sequence in the promoters of many amino acid biosynthetic genes for general control. A new random saturation mutagenesis method was developed to isolate Gcn4p derivatives with only one or two mutations in the DNA binding domain without using radioactive isotope. This will be used to identify the amino acids of Gcn4p involved in protein-protein interactions. Saturation mutagenesis in the DNA binding domain of Gcn4p was performed using spiked degenerate oligonucleotides containing randomized codon bases designed specifically for only one or two base changes in the mutagenized area. These oligonucleotides were synthesized to have two flanking restriction enzyme sites for cloning to the appropriate vector. The 3' ends were mutually primed after hybridization via the palindromic sequences of the restriction enzyme sites. These molecules were then converted to double stranded DNA upon treatment with DNA polymerase. Here, a library collection of 100,680 in an altered Gcn4p pool was generated by cloning a mixed-base oligonucleotide in the place of the sequence coding for the DNA binding domains. The quality of the library was examined by DNA sequencing and found to be in good agreement with the expected statistical values. Calculated mutation frequency was 66% of mutant nucleotide rate and actual sequencing data revealed 68% mutant nucleotide rates from the sequenced library. Thus, among 21 mutants, 16 had one point mutations and 5 had two point mutations. This approach appears to be an effective and general tool for creating proteins with one or two amino acid change(s) in their molecules.

The impact of family planning service provision on contraceptive-use dynamics in Morocco

This article uses linked data from the 1995 Morocco DHS calendar and the 1992 Morocco DHS service-availability module to study the effect of service environment on contraceptive discontinuation, switching, and adoption of a modern method following a birth. The 1995 Morocco DHS also collected information on the source of supply for each episode of use of a modern method recorded in the calendar, allowing study of the association between the source of supply and discontinuation and switching rates. Multilevel event-history models are used to evaluate the impact of individual-level sociodemographic characteristics and community-level indicators of family planning service provision. The findings show that the presence of a nearby public health center is associated with higher modern-method adoption after a birth and lower method-failure rates; the presence of a pharmacy is associated with lower discontinuation due to side effects or health concerns. The degree of method-choice potential has a positive impact on both the rate of switching from the pill to another modern method and on modern-method adoption after a birth.

Angiodysplasia as the cause of massive lower gastrointestinal hemorrhage in a young adult. Report of a case

PURPOSE

This study was undertaken to clarify the importance of bleeding vascular ectasia of the colon as the etiology of massive lower gastrointestinal hemorrhage in patients 40 years of age or younger.

METHODS

An otherwise healthy 21-year-old male was admitted to a tertiary medical center with massive lower gastrointestinal hemorrhage. Technetium-labeled red blood cell scan, selective visceral angiography, and colonoscopy identified the source of bleeding as vascular abnormality of the descending colon. Segmental colonic resection was performed.

RESULTS

Histologic review of the specimen demonstrated a vascular ectasia. The patient recovered uneventfully and has had no further stigmata of hemorrhage. A review of the literature was undertaken to make clear the significance of vascular ectasia as the source for massive colonic hemorrhage in the young adult.

CONCLUSION

This is the first report that documents histologically a vascular ectasia as the source of massive lower gastrointestinal hemorrhage in an otherwise healthy patient less than 40 years of age. Vascular ectasia is an uncommon cause of lower gastrointestinal hemorrhage in the young adult.

Lipid peroxidation contributes to age-related membrane rigidity

The aim of this work was to assess the relative contributions of lipid peroxidation and cholesterol content to the increase in membrane rigidity observed during senescence. Membrane fluidity was manipulated through exposure to peroxidized or cholesterol-loaded liposomes. Small unilamella liposomes were prepared and either peroxidized by Fe(++)-ADP-ascorbic acid or loaded with cholesterol. After incorporation of the liposomes into rat liver microsomal membranes, membrane fluidity was quantitated by measuring changes in polarization. Membranes exhibited a greater sensitivity to peroxidation than cholesterol in that incorporation of peroxidized liposomes induced microsomal membrane rigidity substantially more than did cholesterol-loaded liposomes. Thus it is proposed, based on data from the present and earlier studies, that membrane fluidity can be modulated readily by lipid peroxidation of membrane phospholipids, irrespective of the influences of cholesterol. These results support the proposal that alterations of lipid structure are more potent and effective than compositional changes in cholesterol in inducing age-related increases in membrane rigidity.

B3(Fab)-PE38M: a recombinant immunotoxin in which a mutant form of Pseudomonas exotoxin is fused to the Fab fragment of monoclonal antibody B3

Recombinant immunotoxins were made by fusing the Fab domain of monoclonal antibody (MAb) B3 to PE38M, a truncated mutant form of Pseudomonas exotoxin (PE). The recombinant toxins were made in Escherichia coli by fusing genes encoding the antibody domains to a gene encoding the mutant form of PE. MAb B3 binds to a carbohydrate antigen found on many kinds of carcinomas. Immunotoxins in which MAb B3 has been chemically coupled to recombinant forms of PE have been shown to be very active cytotoxic agents. PE has also been targeted to tumor cells by replacing the cell-binding domain of PE (domain I) with a single-chain antibody to make a single-chain immunotoxin. In the current study, PE38M, a mutant form of PE, with a deletion of the cell-binding domain (amino acids 1-252) as well as mutations in domain III and some nonessential sequences in domain Ib (amino acids 365-380), was fused to the light chain of MAb B3. This protein was renatured in the presence of the Fd fragment of MAb B3 to produce a Fab-toxin fusion protein. Alternatively, the Fd fragment of MAb B3 was fused to PE38M and combined with the light chain. Both types of B3(Fab)-PE38M were just as active on target cells as previously described single-chain immunotoxins. Furthermore, the B3(Fab)-PE38M produced complete remissions of human tumor xenografts growing in nude mice. B3(Fab)-PE38M has two advantages over single-chain immunotoxins. One is that the yield of recombinant Fab-toxin is very high, with 10-22% of the starting protein recovered as cytotoxically active immunotoxin after chromatographic purification. The second is that the B3(Fab)-PE38M has a much longer survival in the circulation of mice with a t1/2 beta of approximately 5 h.

Protein kinase C activity is reduced in epidermal cells from energy-restricted SENCAR mice

Female SENCAR mice were pre-fed a control or 40% energy-restricted (ER) diet with energy removed from fat and carbohydrate, or a control, balanced high fat (BHF, with similar energy from fat and carbohydrate), 35% energy restricted from fat (HCR) or 35% energy restricted from carbohydrate (HFR) diet. Epidermal cells were isolated by trypsin digestion for measurement of protein kinase C (PKC) activity, lipid composition or lipid metabolism. Dietary restriction of fat or carbohydrate energy (HFR or HCR group) reduced particulate PKC activity in epidermal cells compared with cells from control mice. The ratio of soluble particulate PKC activity was higher in epidermal cells from mice fed the HCR diet compared with those fed the HFR diet. Diet did not affect soluble PKC activity. Inositol accumulation was measured in the water- or lipid-soluble fractions of prelabeled ([3H]inositol) epidermal cells following a 1-h incubation in media with LiCl. Phosphatidylinositol, inositol biphosphate and inositol triphosphate fractions were more heavily labeled in cells from mice fed the ER diet. Energy restriction did not modify epidermal total lipid or phospholipid composition, but 1,2-diacylglycerol levels were elevated in relation to cell number in epidermal cells from mice fed the ER diet. These data suggest that dietary energy restriction modified PKC activity through a pathway other than alteration in membrane lipid composition or inositol lipid metabolism.

Identification of the regulatory sequence of anaerobically expressed locus aeg-46.5

A newly identified anaerobically expressed locus, aeg-46.5, which is located at min 46.5 on Escherichia coli linkage map, was cloned and analyzed. The phenotype of this gene was studied by using a lacZ operon fusion. aeg-46.5 is induced anaerobically in the presence of nitrate in wild-type and narL cells. It is repressed by the narL gene product, as it showed derepressed anaerobic expression in narL mutant cells. We postulate that aeg-46.5 is subject to multiple regulatory systems, activation as a result of anaerobiosis, narL-independent nitrate-dependent activation, and narL-mediated repression. The regulatory region of aeg-46.5 was identified. A 304-bp DNA sequence which includes the regulatory elements was obtained, and the 5' end of aeg-46.5 mRNA was identified. It was verified that the anaerobic regulation of aeg-46.5 expression is controlled on the transcriptional level. Computer analysis predicted possible control sites for the NarL and FNR proteins. The proposed NarL site was found in a perfect-symmetry element. The aeg-46.5 regulatory elements are adjacent to, but divergent from, those of the eco gene.

Protein kinase C is activated and diacylglycerol is elevated in epidermal cells from Sencar mice fed high fat diets

Studies reported here determined the effect of dietary fat level on membrane phospholipid composition, phosphoinositide labeling, 1,2-sn-diacylglycerol and protein kinase C activity in epidermal cells from female Sencar mice. Animals were fed either high fat (24.6 g/100 g diet) or control (5 g/100 g diet) diets at constant energy intake for 6 to 7 wk or 15 to 22 wk, and epidermal cells were isolated. The level of phosphatidylinositol was significantly lower in the animals fed the control diet than in the animals fed the high fat diet (0.6 vs. 1.2 nmol/10(6) cells). The fatty acid composition of the phospholipids showed significantly lower arachidonic acid level in phosphatidylinositol when the animals were fed the high fat diet. Protein kinase C activity in the solubilized particulate and soluble fraction of the cells was 131 +/- 18% and 62 +/- 14% greater, respectively, in animals fed the high fat diet compared with animals fed control diet. The level of 1,2-sn-diacylglycerol was significantly higher in animals fed the high fat diet (mean nmol/mg lipid +/- SEM: control, 4.5 +/- 0.5; high fat, 7.0 +/- 0.5). Incorporation of [3H]inositol into inositol lipid was not altered by diet. Because protein kinase C and 1,2-sn-diacylglycerol have been implicated in tumor promotion, the increase in protein kinase C activity and the elevation of 1,2-sn-diacylglycerol in cells from animals fed the high fat diet may be important in the high cancer rate observed with these diets.

Dietary energy and fat effects on tumor promotion

We investigated dietary modulation, by energy level and energy source, of two-stage skin tumorigenesis initiated with 7,12-dimethylbenz(a)anthracene and promoted with 12-O-tetradecanoylphorbol-13-acetate in SENCAR mice. Studies comparing the influence of dietary calorie restriction (feeding less carbohydrate and less fat) with diet restriction and with ad libitum control feeding indicated an inhibition of papillomas and carcinomas in both restricted groups. The inhibition was greatest in the calorie-restricted group. We reported an increase in the number and incidence of papillomas and the earlier appearance of carcinomas in mice fed a high-fat diet during promotion, in comparison with control groups fed the same calorie allotment. Recent work compared restriction of fat calories (high carbohydrate, restricted fat) with restriction of carbohydrate calories (high fat, restricted carbohydrate), and both protocols resulted in fewer papillomas and carcinomas. Restriction of fat calories resulted in a greater inhibition of papillomas, whereas carcinoma rates were comparable with both protocols. Protein kinase C activity in epidermal cells from mice fed the high-fat diet was higher than activity from mice fed the control diet. Calorie restriction reduced protein kinase C activity. Phosphatidylinositol-inositol phosphate labeling studies suggest alteration of inositol lipid turnover in epidermal cells from mice fed a calorie-restricted diet.

Anaerobically expressed Escherichia coli genes identified by operon fusion techniques

Genes that are expressed under anaerobic conditions were identified by operon fusion techniques with a hybrid bacteriophage of lambda and Mu, lambda placMu53, which creates transcriptional fusions to lacZY. Cells were screened for anaerobic expression on XG medium. Nine strains were selected, and the insertion point of the hybrid phage in each strain was mapped on the Escherichia coli chromosome linkage map. The anaerobic and aerobic expression levels of these genes were measured by beta-galactosidase assays in different medium conditions and in the presence of three regulatory mutations (fnr, narL, and rpoN). The anaerobically expressed genes (aeg) located at minute 99 (aeg-99) and 75 (aeg-75) appeared to be partially regulated by fnr, and aeg-93 is tightly regulated by fnr. aeg-60 requires a functional rpoN gene for its anaerobic expression. aeg-46.5 is repressed by narL. aeg-65A and aeg-65C are partially controlled by fnr but only in media containing nitrate or fumarate. aeg-47.5 and aeg-48.5 were found to be anaerobically induced only in rich media. The effects of a narL mutation on aeg-46.5 expression were observed in all medium conditions regardless of the presence or absence of nitrate. This suggests that narL has a regulatory function in the absence of exogenously added nitrate.

Dietary fat regulation of the association of protein kinase C activity with epidermal cell membranes

An apparent redistribution of protein kinase C activity was noted in the particulate and soluble fractions of basal epidermal cells isolated from mice receiving semi-purified diets varying in fat content. An increase in the amount of protein kinase C activity in the particulate fraction and a decrease in the soluble fraction were observed with the mice fed high-fat (24.6% corn oil) diet as compared with those given the low-fat (5% corn oil) diet. Increased levels of phospholipids and an increase in 18:2 and 18:3 side chains of the phospholipids were observed with the high-fat diet.

Secretion of particles of hepatitis B surface antigen from insect cells using a baculovirus vector

The coding sequences of the hepatitis B virus surface antigen were inserted into a baculovirus transfer vector produced from Autographa californica nuclear polyhedrosis virus (AcNPV) so that the foreign gene was under the control of the AcNPV polyhedrin promoter. Spodoptera frugiperda cells infected with the derived recombinant baculovirus produced and secreted 22 nm particles containing the hepatitis B surface antigen. The particles had morphological and antigenic properties identical to those of 22 nm particles isolated from the plasma of chronic active hepatitis patients.