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T Nowak

Publications and source records attributed to T Nowak.

At least 37 records · Page 2Linked to original sources
PubMed1998

pH dependence of the reaction catalyzed by yeast Mg-enolase.

The pH dependence of the chemical shifts of the 31P resonances of enzyme-bound substrates 2-phosphoglycerate (PGA) and phosphoenolpyruvate (PEP) were measured to obtain further insight into the catalytic mechanism of yeast enolase. The 31P resonances of PGA and PEP bound to the enolase-Mg complex are individually observed by NMR. The Keq,internal = 1.5 favoring PEP was measured. A pH dependence of the 31P chemical shifts gives pKa values of 5.82 and 6.16 for bound PGA and PEP, respectively, indicating that both ligands bind predominantly with their phosphate groups as the dianionic species and their ionization has been altered. The phosphoryl group of PGA has been suggested as playing a role in catalysis [Nowak, T., Mildvan, A. S., and Kenyon, G. L. (1973) Biochemistry 12, 1690-1701]. The pH dependence of the kinetic parameters for Mg-enolase shows a single break in the plot of pKm, PGA vs pH at pH 6.27 with a pH independence above pH 7. This is consistent with the trianion of PGA preferably binding to the enzyme. The kcat profile gives pKA values of 5.94 and 8.35, and kcat/Km profiles give pKA values of 5.85, 6.25, and 8.39. Activation studies with Mg2+ show a pH independence for the activator constant (Ka), but a pH-dependent inhibition at higher concentrations of Mg2+. The log kcat and kcat/Ka profiles from Mg2+ activation give pKA values of about 5.9 and 8.4. These results confirm the importance of residues with pKA values of about 5.9 and 8.4 (His and Lys residues?) but do not support a function for the phosphoryl group of the substrate. The pH dependence of the Ki,Mg2+ gives pKA fits of 5. 95, 7.13, and 8.35. Data from cation inhibition suggest that the phosphate of the substrate and a His residue on enolase may bind the inhibitory Mg2+.

Buffers↗
PubMed1998

Chromium(III) modification of the first metal binding site of phosphoenolpyruvate carboxykinase.

Chicken liver phosphoenolpyruvate carboxykinase (PEPCK) is activated by Cr2+ as the sole activator under anaerobic conditions. PEPCK was modified with Cr3+, starting with either Cr2+ or Cr3+. Cr3+ has the distinct advantage of being a paramagnetic cation that could serve as a paramagnetic probe. Activators Mn2+, Mg2+, and Co2+ protect against Cr3+ incorporation. EPR, CD, and fluorescence studies indicate that Cr3+ was incorporated into the cation binding site of PEPCK. The water proton relaxation rate (PRR) and fluorescence binding studies showed that Cr3+(n1)-PEPCK forms enzyme-substrate complexes similar to those observed for the Mn2+(n1)-PEPCK complex (n1 represents the metal "enzyme binding site" as opposed to the metal "nucleotide binding site"). Cr3+(n1)-PEPCK requires an additional divalent cation for activity, an indication of two metal sites on PEPCK. Cr3+(n1)-PEPCK retains 15% residual activity as compared to unmodified PEPCK and demonstrates normal Michaelis-Menten kinetics. This is the first report of an active Cr3+-modified enzyme complex.

Animals↗
PubMed1998

Conformational changes in yeast pyruvate kinase studied by 205Tl+ NMR.

The interaction of the monovalent cation with yeast pyruvate kinase (yPK) has been investigated by 205Tl+ NMR. TlNO3 activates yPK to 80-90% activity compared to KCl with an apparent Ka of 1.00 +/- 0.03 mM in the presence of 4 mM Mn(NO3)2 as the activating divalent cation. At higher concentrations of Tl+, enzyme inhibition is observed with an apparent KI of 180 +/- 10 mM. The extent of inhibition is dependent on the nature and concentration of the divalent cation. The effect of Mn2+ on the 1/T1 and 1/T2 values of 205Tl+ in the presence of yPK was determined at 173.02 MHz (300 MHz, 1H) and 346.03 MHz (600 MHz, 1H). The temperature dependence of the relaxation rates indicates that fast exchange conditions prevail for 205Tl+ longitudinal relaxation rates. The correlation time, tauc, for the Mn2+-205Tl+ interaction was estimated by a frequency dependence of 1/T1m for several enzyme complexes, and an average value of tauc was determined to be 0.91 ns. The distance between Tl+ and Mn2+ at the active site of yPK was calculated from the paramagnetic contribution of Mn2+ to the longitudinal (1/T1m) relaxation rates of Tl+ bound to yPK. For the apo yPK complex, the Tl+ to Mn2+ distance is 6.7 +/- 0.2 A. Upon addition of phosphoenolpyruvate (PEP) to form the yPK-Tl-Mn-PEP complex, the inter-cation distance decreases to 6.1 +/- 0.3 A. The addition of the allosteric activator fructose 1,6-bisphosphate (FBP) to form the yPK-Tl+-Mn2+-PEP-FBP complex gives an intermetal distance of 6.2 +/- 0.2 A. In the yPK-Tl-Mn-FBP complex, a Tl+-Mn2+ distance of 6.0 +/- 0.1 A is observed, indicating that FBP causes a conformational change at the active site in the absence of PEP. Analogous 205Tl NMR experiments with competitive inhibitors of PEP (oxalate, BrPEP) indicate that these ligands do not induce the same conformational changes as do the physiological substrates and activators. Similar experiments with the nonallosteric rabbit muscle PK were also performed and analyzed.

Animals↗
PubMed1998

The allosteric regulation of pyruvate kinase by fructose-1,6-bisphosphate.

BACKGROUND: Yeast pyruvate kinase (PK) catalyzes the final step in glycolysis. The enzyme therefore represents an important control point and is allosterically activated by fructose-1,6-bisphosphate (FBP). In mammals the enzyme is found as four different isozymes with different regulatory properties: two of these isozymes are produced by alternate splicing. The allosteric regulation of PK is directly related to proliferation of certain cell types, as demonstrated by the expression of an allosterically regulated isozyme in tumor cells. A model for the allosteric transition from the inactive (T) state to the active (R) state has been proposed previously, but until now the FBP-binding site had not been identified. RESULTS: We report here the structures of PK from yeast complexed with a substrate analog and catalytic metal ions in the presence and absence of bound FBP. The allosteric site is located 40 A from the active site and is entirely located in the enzyme regulatory (C) domain. A phosphate-binding site for the allosteric activator is created by residues encoded by a region of the gene corresponding to the alternately spliced exon of mammalian isozymes. FBP activation appears to induce several conformational changes among active-site sidechains through a mechanism that is most likely to involve significant domain motions, as previously hypothesized. CONCLUSIONS: The structure and location of the allosteric activator site agrees with the pattern of alternate genetic splicing of the PK gene in multicellular eukaryotes that distinguishes between a non-regulated isozyme and the regulated fetal isozymes. The conformational differences observed between the active sites of inactive and fully active PK enzymes is in agreement with the recently determined thermodynamic mechanism of allosteric activation through a 'metal relay' that increases the affinity of the enzyme for its natural phosphoenolpyruvate substrate.

Allosteric Regulation↗
PubMed1998

[The role of local surgical and radiological control in the treatment of soft tissue sarcoma sensitive to chemotherapy in children. Report of Polish Pediatric Solid Tumors Treatment Group].

In this paper the role local surgical and radiological control in the treatment of soft tissue sarcomas in children was analyzed. All children were treated according to CWS-91 and SIOP-IV protocols. Eighty three children with RMS A + E, EES/PNET, SS, UDS were included in the analysis. The primary surgery consisted of R0 (5%), R1 (18%) or R2 (16%) resection. In majority of cases (61%) primary surgical intervention was limited to diagnostic biopsy. Conventional or hyperfractionated radiotherapy was performed in 42.8%, 73.8% and 75% of children with disease stage II, III and IV, respectively. Delayed surgery was performed in 20 out of 53 (37.7%) children with stage III of the disease. In 5 patients without primary focus (urinary bladder in 3 and prostate in 2 cases) removed, progression of the disease occurred. In 5 children (stage IV) with progression of the disease no secondary surgery was performed. In 4 of them the primary tumor exceeded 10 cm in diameter. No delayed surgery was performed in 69% of relapsed children with stage III of the disease. Planned radiation therapy was not performed in 15.9% of cases. Primary local surgical control of primary tumor is of great importance for remission duration. In children who underwent delayed surgery the estimated EFS was of 0.7, in comparison with 0.5 EFS of those without secondary surgical treatment.

Adolescent↗
PubMed1997

Affinity cleavage at the metal-binding site of phosphoenolpyruvate carboxykinase.

Chicken liver phosphoenolpyruvate carboxykinase (PEPCK) was rapidly inactivated by micromolar concentrations of ferrous sulfate in the presence of ascorbate at pH 7.4. Omitting ascorbate or replacing the Fe2+ with Mn2+ or Mg2+ gives no inactivation. Mn2+, Mg2+, or Co2+ at 100-fold molar excess over Fe2+ offered complete protection from Fe2+/ascorbate-induced inactivation. The substrates PEP and GTP, but not OAA, GDP, or CO2, offered full protection from inactivation. The addition of 5 mM EDTA stopped further inactivation of the enzyme. Thermodynamic studies indicate that the inactive enzyme no longer binds Mn2+ but still had high affinity for GTP indicating that the inactivation process was specific for the metal site. A decrease in cysteine content was observed over time following PEPCK treatment with Fe2+ and ascorbate. The apparent first-order rate constant for free sulfhydryl loss (0.085 +/- 0.005 min-1) is similar to the apparent first-order rate constant for inactivation (0.067 +/- 0.005 min-1). Amino acid composition analysis revealed that cysteic acid was generated upon Fe2+/ascorbate addition to PEPCK. Native chicken liver PEPCK has an Mr of 67 kDa. SDS-PAGE of the inactivated enzyme showed the presence of two new bands at 31.7 and 35.3 kDa indicating that PEPCK was specifically cleaved at a single site. The rate of cleavage was slower than the rate of inactivation and fully inactivated enzyme was only 50% cleaved. The Fe2+/ascorbate-catalyzed inactivation was not solely due to protein cleavage. The protein fragments generated by cleavage were separated by C4 reverse phase HPLC. The cleavage exposed a new N-terminus which was identified to be the 35.3 kDa C-terminal half of PEPCK. Sequencing of the fragments indicated that the site of cleavage was between Asp296 and Ile297. These results indicate that Asp296 is involved in metal chelation. This agrees with previous studies [Hlavaty, J. J., & Nowak, T. (1997) Biochemistry 36, 3389-3403] that suggested that Asp295 and Asp296 are involved in metal binding.

Amino Acid Sequence↗
PubMed1997

Metal-ion-mediated allosteric triggering of yeast pyruvate kinase. 1. A multidimensional kinetic linked-function analysis.

Regulation of the glycolytic pathway is considered to be primarily achieved by the carbon metabolites resulting from glucose metabolism [e.g., fructose 1,6-diphosphate (FDP), phosphoenolpyruvate (PEP), and citrate] and by the ATP charge of the cell. The divalent cations (e.g., Mg2+ and Mn2+) have not been considered as having regulatory roles in glycolysis, although they are involved in almost every enzyme-catalyzed reaction in the pathway. Using a kinetic linked-function analysis of steady-state kinetic data for the interactions of PEP, FDP, and Mn2+ with yeast pyruvate kinase (YPK), we have found that the divalent metal is the principal trigger of the allosteric responses observed with this enzyme. The interaction of Mn2+ to YPK enhances the interaction of FDP by -1.6 kcal/mol and the interaction of PEP by -2.8 kcal/mol. The simultaneous interaction of all three of these ligands to YPK is favored by -4.3 kcal/mol over the sum of their independent binding free energies. Surprisingly, the binding of the allosteric activator FDP does not directly influence the binding of the substrate PEP since a coupling free energy near zero was calculated for these two ligands. Thus, communication between the PEP and FDP sites occurs structurally through the metal by an allosteric relay mechanism. These conclusions are supported by results of a thermodynamic linked-function analysis of direct binding data for the interactions of PEP, FDP, and Mn2+ with YPK [Mesecar, A. D., & Nowak, T. (1997) Biochemistry (following paper in this series)]. Our findings raise important questions as to the possible roles of divalent metals in modulating multiligand interactions with YPK and in the regulation of the glycolytic pathway.

Adenosine Diphosphate↗
PubMed1997

Metal-ion-mediated allosteric triggering of yeast pyruvate kinase. 2. A multidimensional thermodynamic linked-function analysis.

A role has been proposed for the free divalent metal in triggering the allosteric responses of yeast pyruvate kinase based upon a kinetic linked-function analysis [Mesecar, A. D., & Nowak, T. (1997a) (preceding paper in this series)]. The major conclusion from the analysis is that the allosteric activator, fructose 1,6-diphosphate (FDP), does not directly communicate with the substrate, phosphoenolpyruvate (PEP), at the active site of the enzyme: it is Mn2+ that mediates the allosteric communication between the PEP and FDP sites in an allosteric relay mechanism. Assumptions were necessary to treat kinetic parameters as thermodynamic parameters, and the presence of the substrate ADP was necessary for the kinetic analysis. In this study, the influence of FDP on the interactions of PEP and Mn2+ and the influence of PEP and Mn2+ on the interaction of FDP with YPK were measured, where possible, by direct binding methods in the absence of ADP. Direct binding data were then subjected to a thermodynamic linked-function analysis for a heterotropic, three ligand coupled system in order to ascertain the two and three ligand coupling free energies. The two ligand coupling free energies deltaG(Mn-PEP), deltaG(Mn-FDP), and deltaG(PEP-FDP) are -3.88, -1.09, and -0.22 kcal/mol, respectively. These values indicate that positive, heterotropic interactions exist between each of these ligand pairs. The three ligand coupling free energy term, deltaG(Mn-PEP-FDP), indicates that simultaneous binding of Mn2+, PEP, and FDP is considerably favored over the sum of their independent binding free energies by -6.6 kcal/mol. These results demonstrate the key role of the metal in the modulation of ligand binding and are consistent with the values and the relationships of the kinetic parameters obtained from the kinetic linked-function analysis.

Adenosine Diphosphate↗
PubMed1997

Formation and characterization of an active phosphoenolpyruvate carboxykinase-cobalt(III) complex.

Avian mitochondrial phosphoenolpyruvate carboxykinase (PEPCK) was incubated with Co2+ and H2O2 to form a stable Co3+-PEPCK complex. PEPCK, similarly incubated with H2O2 and either Mg2+ or Mn2+, resulted in no significant loss in activity over 30 min. PEPCK, incubated with Co2+ and H2O2 at pH 7.4, showed rapid inhibition as observed by a 40% decrease in activity after 5 min. The loss of activity is linear with the incorporation of cobalt into PEPCK, resulting in 15-25% activity for the stoichiometric Co3+-PEPCK complex. The incorporation of and inhibition by Co3+ is protected by PEP and GTP (ITP). Treatment of the Co3+-PEPCK complex with beta-mercaptoethanol results in a loss of cobalt and full recovery of activity. The reduction and reactivation are protected by PEP and GTP (ITP). EPR, PRR, circular dichroism, and fluorescence studies all indicate that Co3+ has been selectively incorporated into the cation site of PEPCK, resulting in a catalytically active enzyme-cation species. The substrates form Michaelis complexes with Co3+-PEPCK, and the catalytic reaction occurs as a second sphere complex as previously suggested [Lee & Nowak (1984) Biochemistry 23, 6506); Duffy & Nowak (1985) Biochemistry 24, 1152]. Proteolytic digestion of the Co3+-PEPCK complex and isolation of the cobalt-containing peptide by reverse phase HPLC were performed to identify the location of the cation binding site. From mass, amino acid composition, and sequence analyses of the isolated cobalt-peptide, the region Thr276-Lys301 is responsible for metal chelation. This very homologous region, located in the central portion of PEPCK, contains two highly conserved aspartic acids, Asp295 and Asp296, that are the only feasible metal binding ligands.

Amino Acid Sequence↗
PubMed1997

Analysis of human plasma products: polymerase chain reaction does not discriminate between live and inactivated viruses.

BACKGROUND: The viral safety of human plasma products is based on the careful selection of donors and donations and the removal and inactivation of human pathogenic viruses that could potentially contaminate human plasma. For the analysis of the final products for potential virus contamination, the use of polymerase chain reaction (PCR) has been proposed. To test whether this method can discriminate between infectious and inactivated viruses, the following studies were performed. STUDY DESIGN AND METHODS: Infectious and virus-inactivated preparations were titrated with specific PCR, using viruses such as hepatitis B virus (HBV), hepatitis C virus, bovine viral diarrhea virus, and poliovirus. The inactivation method employed was pasteurization (10 hours, 60 degrees C) or solvent/detergent (SD) treatment; in the case of HBV, there was consecutive treatment by both methods. RESULTS: Pasteurization of HBV and hepatitis C virus as well as SD treatment of HBV or pasteurization of HBV followed by SD treatment did not affect the detectability of these viruses by PCR, whereas an infectivity study in chimpanzees demonstrated that infectious hepatitis C virus was inactivated by pasteurization. Pasteurization also had no effect on the PCR titers of stabilized bovine viral diarrhea virus or poliovirus preparations, but it destroyed the infectivity of these viruses completely after only 4 hours' heat treatment. CONCLUSION: Pasteurization or SD treatment destroys the infectivity of the viruses tested, but neither significantly affects their detectability by specific PCR. Therefore PCR is not a suitable measure for testing the viral safety of finished plasma products that have been subjected to virus inactivation.

Animals↗
PubMed1997

Closed-loop subcutaneous insulin infusion algorithm with a short-acting insulin analog for long-term clinical application of a wearable artificial endocrine pancreas.

Considering the management and safety of the insulin delivery route when a wearable artificial endocrine pancreas is applied to ambulatory diabetic patients on a long-term basis, we developed a s.c. insulin infusion algorithm by analyzing the dynamics of a s.c. injected short-acting insulin analog (Insulin Lispro) by a three-compartment model. Principally the insulin infusion algorithm was developed as a transfer function with the first-order delay in both proportional and derivative actions to blood glucose concentrations. The parameters for this algorithm were calculated to simulate a physiological plasma insulin profile as closely as possible. By applying this algorithm with regular insulin, diabetic patients showed a 2 h postprandial hyperglycemia and a delayed hyperinsulinemia, followed by hypoglycemic episodes 4-5 h after oral glucose load, just as observed in the computer simulation study. However, using Insulin Lispro, a near-physiological glycemic control (postprandial blood glucose of 153.1 +/- 8.3 mg/100 ml at 60 min and 90.3 +/- 7.1 mg/100 ml at 180 min, respectively) could be achieved without showing any delayed hyperinsulinemia or hypoglycemia. Daily glycemic excursions were also controlled near-physiologically and although the daily insulin requirement (731.7 +/- 160.5 mU/kg/day) was slightly higher, it was not significantly different from that with i.v. insulin infusion (622.3 +/- 142.6 mU/kg/day). These results indicate that the application of s.c. insulin infusion algorithm with Insulin Lispro is feasible for long-term glycemic control with a wearable artificial endocrine pancreas in ambulatory diabetic patients.

Adult↗
PubMed1996

[Nanofiltration in production of Beriplex P/N: increasing the capacity of virus elimination while maintaining product quality].

For the manufacture of the PCC Beriplex P/N, nanofiltration was introduced into the production process of Beriplex HS providing an additional means to heat treatment for the clearance/inactivation of viruses. By nanofiltration, large enveloped viruses (HSV-1, HIV-1) were completely eliminated by a factor of more than 7 log10. While medium-sized enveloped viruses (HBV, BVDV) were cleared by a factor of approximately 4 log10, small non-enveloped viruses (poliovirus) were not removed. The product profile remained, no thrombogenic activities were detected.

Blood Coagulation Factors↗
PubMed1995

Glycerophosphorylcholine, a component of both Ascaris suum muscle and Caenorhabditis elegans.

Studies of the muscle phospholipid metabolism of Ascaris suum suggest an effect of cholinergic drugs on the turnover of phosphatidylcholine and the generation of glycerophosphorylcholine (GPC). 31P-nuclear magnetic resonance (NMR) studies of helminths revealed the presence of a major peak that was assigned to GPC. The primary effect of the cholinergic drugs on the parasites' phosphate profile appeared to be on the level of GPC. In in vivo studies, decreases in internal GPC concentrations occurred prior to any decrease in the concentration of ATP. The importance of these studies relies on the correct identity of this major 31P-NMR resonance. More recently, the identity of this resonance as GPC was questioned by experimental data obtained from C. elegans dauer larvae using the NMR technique. Because studies from our laboratory suggested that phospholipid metabolism may be intimately connected with the parasite's responses to drugs, the identity of the assigned resonance in the 31P-NMR spectrum as GPC in Ascaris suum was reexamined and found to be correct. Similar studies with C. elegans indicate the presence of both GPC and GPE.

Animals↗
PubMed1994

Implantable electrocatalytic glucose sensor.

An electrocatalytic glucose sensor for in vivo application has been developed to determine the glucose level in blood and further to control the insulin dosage in a closed loop system for diabetes therapy. The principle of the electrocatalytic glucose sensor is based on the direct electrochemical oxidation of glucose at a membrane-covered platinum electrode. For a possible clinical application the sensor was built as a catheter. A set of implantations in the vena cava of sheep demonstrated the potential feasibility of the sensor. The sensor values were simultaneously checked by the enzymatic analysis of glucose in blood samples drawn separately from a femoral vein. It was possible to determine the glucose concentration in sheep for more than 130 days with tolerable deviations from glucose reference measurements. The mean error was 2.5 mmol/l. One of the catheters was explanted after 211 days and the histological examination revealed a good biocompatibility of all materials used. In additional experiments, the differences of the glucose concentration in vena cava as well as in the anterior and posterior femoral veins of a sheep were examined during glucose tolerance tests. These experiments verified our method of in vivo calibration of the long-term implantable glucose sensor.

Animals↗
PubMed1994

Electrocatalytic glucose sensor for long-term in vivo use.

A catheter shaped electrocatalytic glucose sensor for in vivo application has been developed to determine the glucose level in blood and control the insulin dosage in a closed loop system for diabetes therapy. The principle of measurement is based on the electrochemical oxidation of glucose at a membrane-covered platium electrode. For various potential steps, the impedance obtained at two different frequencies is a function of the glucose concentration. A series of implantations in the vena cava of sheep demonstrated the potential feasibility of the sensor. It was possible to determine the glucose concentration in sheep for more than 130 days with tolerable deviations from glucose reference measurements. The mean error was 2.5 mmol/l. The catheter was explanted after 211 days and histological examination revealed a good biocompatibility of all materials used.

Animals↗
PubMed1994

Inactivation of hepatitis A virus by pasteurization and elimination of picornaviruses during manufacture of factor VIII concentrate.

Hepatitis A virus (HAV) infections have been reported among hemophiliacs who received factor VIII concentrates which had been purified by ion-exchange chromatography and treated by the solvent detergent (SD) method. Since the virus inactivation procedure of our manufacturing process is heat treatment of the stabilized, aqueous protein solution at 60 degrees C for 10 h (pasteurization), we investigated whether this method inactivated picornaviruses such as HAV and poliovirus type 1, which we routinely use as a test virus for non-enveloped viruses. HAV was substantially inactivated by pasteurization but the stabilizers used in the manufacturing process of the commercial products considerably delayed HAV inactivation. Residual infectious HAV was found even after 10 h heat treatment of the stabilized preparation. Thus HAV is more stable in the presence of stabilizers than poliovirus type 1. Furthermore, we studied stage by stage the elimination of poliovirus type 1 by the manufacturing procedure of these pasteurized factor VIII concentrates. Three other stages of the manufacturing process apart from pasteurization eliminated poliovirus by approximately three orders of magnitude each. Taking into account this efficient elimination of the picornavirus poliovirus and the substantial inactivation of HAV by pasteurization, we conclude that a high margin of safety exists for pasteurized factor VIII concentrates regarding HAV. This conclusion is supported by the fact that no HAV infection has been reported in hemophilia patients treated with pasteurized factor VIII concentrates. Furthermore, in a retrospective study, none of 95 patients subjected to a long-term treatment with pasteurized factor VIII concentrates had developed anti-HAV seroconversion as a result of this treatment.

Drug Contamination↗
PubMed1994

[Splenectomy in adult patients with idiopathic thrombocytopenic purpura after intravenous immunoglobulin treatment].

Eight patients with idiopathic thrombocytopenic purpura (ITP) and no response to steroids therapy were prepared for splenectomy, for 5 consecutive days, with intravenous immunoglobulin (IVIG, 0.4 g/kg body weight). Increase of platelet counts and/or remission of haemorrhagic diathesis were observed in 7 patients, in one case IVIG proved ineffective. Splenectomy was performed in 7 cases and the postoperative course was uneventful. IVIG treatment has proved efficient in preparing ITP patients for splenectomy.

Adolescent↗