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Biomedical subjects

J J Kastelein

Publications and source records attributed to J J Kastelein.

At least 19 recordsLinked to original sources

[Familial hypercholesterolemia: recognition and prevention of cardiac complications at a young age].

A man aged 35 and a woman aged 30 visited a lipid clinic because of a raised total cholesterol level, which was also present in a number of first-degree relatives. Apart from the lipid abnormalities they had no risk factors for coronary disease. Both proved to have familial hypercholesterolaemia. The man had vague angina pectoris symptoms and a high dose of cholesterol synthesis inhibitors was prescribed. Coronary angiography showed severe stenoses; a coronary balloon angioplasty was successfully performed. The woman, however, died at age 33 suddenly from myocardial infarction. Familial hypercholesterolaemia may cause unexpected cardiovascular complications and sudden death of young persons. Timely diagnosis of the condition on the basis of adequate anamnesis and thorough physical examination, more rapid administration of cholesterol-lowering agents and alertness for anginous complaints may prevent myocardial infarctions and save lives in these patients.

Adult↗

[Higher prevalence of familial hypercholesterolemia than expected in adult patients of four family practices in Netherlands].

OBJECTIVE: To determine the prevalence of familial hypercholesterolaemia (FH). DESIGN: Patient record screening, questionnaire and if necessary, case finding. METHODS: Over the period mid-1990-mid-1992 (approximately 2.5 years) 8,800 adult individuals (age 18 years and over) in 4 general practices in Hoofddorp, the Netherlands, were screened for risk factors for coronary artery disease and invited for further analysis. Of the 3,289 selected and invited individuals 2,719 (83%) were investigated. Total cholesterol concentrations were investigated 3 times and if the mean value was above 8.0 mmol/l patients were referred to a lipid clinic to investigate the possible existence of FH. RESULTS: 114 patients were eligible for referral to a lipid clinic of whom 92 (81%) were indeed referred. Of these, 38 patients were diagnosed with FH: 23 men and 15 women, with a mean age of 47.7 years (range: 21-74). CONCLUSION: The prevalence of FH in this investigated population was at least 1:232. This is more than 1:500, the estimated number of FH patients in the Dutch population.

Adult↗

Long term survivors of childhood brain cancer have an increased risk for cardiovascular disease.

BACKGROUND: Cranial irradiation for children with brain tumors frequently leads to neuroendocrine deficiencies. In this controlled study, the authors investigated risk factors for cardiovascular disease (CVD) for long term survivors of childhood brain cancer. They also tested whether the presence of these risk factors was related to endocrine status. METHODS: In 26 survivors of childhood brain cancer (mean age, 25.8 years; mean posttreatment interval, 16 years) and 29 healthy controls (mean age, 27.7 years), the blood pressure, smoking habits, body mass index (BMI), and waist/hip (W/H) ratio were determined. Lipids and lipoproteins were measured and endocrine function was assessed. Carotid intima-media thickness (IMT) measurements were performed by high resolution ultrasonography. RESULTS: In the survivors of childhood brain cancer, systolic blood pressure and W/H ratio were elevated compared with controls. The cholesterol/high density lipoprotein ratio (4.7 +/- 1.7 vs. 3.4 +/- 0.8 mmol/L, P = 0.0005), low density lipoprotein cholesterol level (3.3 +/- 0.9 vs. 2.8 +/- 0.6 mmol/L, P = 0.027), and apolipoprotein B level (P = 0.001) were higher in survivors of childhood brain cancer, whereas HDL cholesterol was lower (P = 0.005). The IMT was increased in the survivor group, but only in the carotid bulb (0.63 mm +/- 1.6 vs. 0.53 mm +/- 1.1, P = 0.02), not in the internal or common carotid artery. In the absolute growth hormone deficient (GHD) population (n = 9), LDL cholesterol and apolipoprotein B levels were elevated and the W/H ratio was particularly increased compared with the other survivors of childhood brain cancer. CONCLUSIONS: For long term survivors of brain cancer, the risk for CVD is strongly increased due to dyslipidemia, central obesity, and elevated systolic blood pressure, particularly for those with GHD. The first effects of this increased risk for CVD were observed in the carotic bulb, as assessed by IMT measurements. Efforts should be directed at CVD prevention by risk factor control.

Adolescent↗

[Statins: possibly more than just lowering of the lipid level].

Clinical trials have demonstrated that treatment of hypercholesterolemia with HMG-CoA reductase inhibitors (statins) is beneficial in primary and secondary prevention of vascular diseases. The observed reduction in cardiovascular morbidity and mortality cannot only be explained by lipid-lowering only. Apart from lowering cholesterol, statins conceivably also exert effects on the vascular wall that may directly contribute to decrease of vascular incidents: (a) a favourable influence on endothelial dysfunction through stimulation of nitrous oxide synthetase: (b) stabilization of plaques by reducing influx of macrophages into the vascular wall and decreasing the production of matrix metalloproteinases, that may affect the connective tissue cover of the plaque: (c) inhibition of the initiation and progression of atherosclerosis by reducing adhesion of leukocytes to the vascular wall: (d) reducing the haemorrhagic diathesis by increasing the fibrinolytic capacity and inhibiting tissue factor expression on macrophages. All these effects of statins independent of the lowering of the cholesterol level might contribute to primary and secondary prevention of vascular incidents. While most nonlipid mechanisms of statins are being studied in vitro and in animals, the clinical relevance is still to be determined.

Animals↗

Phenotypic correction of feline lipoprotein lipase deficiency by adenoviral gene transfer.

Previous studies have revealed that adenovirus-mediated ectopic liver expression of human LPL (huLPL) can efficiently mediate plasma triacylglycerol (TG) catabolism in mice despite its native expression in adipose and muscle tissue. We aimed to explore the feasibility of liver-directed gene transfer and enzyme replacement for human LPL deficiency in a larger, naturally occurring feline animal model of complete LPL deficiency that is remarkably similar in phenotype to the human disorder. A cohort of LPL-deficient (LPL -/-) cats was given an intravenous injection of 8 x 10(9) PFU/kg of a CMV promoter/enhancer-driven, E1/E3-deleted adenoviral (Ad) vector containing a 1.36-kb huLPL cDNA (Ad-LPL) or reporter alkaline phosphatase gene (Ad-AP). After Ad-LPL administration, active, heparin-releasable huLPL was readily detected along with a 10-fold reduction in plasma TGs, disappearance of plasma TG-rich lipoproteins up to day 14, and enhanced clearance of an excess intravenous fat load on day 9. However, antibody against the huLPL protein was detected on day 14 in cats receiving Ad-LPL and adenovirus-specific neutralizing antibody was present 7 days after gene transfer in both cat cohorts. Tissue-specific expression of the huLPL transgene relative to controls was confirmed by RT-PCR. While huLPL expression was evident in the liver, other tissues including spleen and lung expressed huLPL message, in direct correlation with histological evidence of increased Oil red O (ORO)-positive neutral lipid influx. In contrast, intravenous LPL enzyme replacement therapy (ERT) led to rapid disappearance of 9000 mU/kg of active bovine LPL enzyme from the circulation, with t1/2 occurring at <10 min in two LPL-/- cats. Heparin injection 1 hr later released <10% of the original bovine LPL, further indicating its rapid systemic clearance, inactivation, or degradation as well as its ineffectiveness as a viable therapeutic alternative for complete LPL deficiency. Although LPL gene transfer and expression via this first-generation Ad vector was limited by the immune response against both the human LPL protein and adenovirus our results clearly provide a key advance supporting further development of LPL gene therapy as a viable therapeutic option for clinical LPL deficiency.

Adenoviridae↗

Lipid-altering efficacy and safety of simvastatin 80 mg/day: long-term experience in a large group of patients with hypercholesterolemia. World Wide Expanded Dose Simvastatin Study Group.

BACKGROUND: Elevated levels of low-density lipoprotein (LDL) cholesterol promote the development of atherosclerosis and coronary heart disease. HYPOTHESIS: Simvastatin 80 mg/day will be more effective than simvastatin 40 mg/day at reducing LDL cholesterol and will be well tolerated. METHODS: Two similar, randomized, multicenter, controlled, double-blind, parallel-group, 48-week studies were performed to evaluate the long-term lipid-altering efficacy and safety of simvastatin 80 mg/day in patients with hypercholesterolemia. One study conducted in the US enrolled patients meeting the National Cholesterol Education Program (NCEP) LDL cholesterol criteria for pharmacologic treatment. In the other multinational study, patients with LDL cholesterol levels > or = 4.2 mmol/l were enrolled. At 20 centers in the US and 19 countries world-wide, 1,105 hypercholesterolemic patients, while on a lipid-lowering diet, were randomly assigned at a ratio of 2:3 to receive simvastatin 40 mg (n = 436) or 80 mg (n = 669) once daily for 24 weeks. Those patients completing an initial 24-week base study were enrolled in a 24-week blinded extension. Patients who had started on the 80 mg dose in the base study continued on the same dose in the extension, while those who had started on the 40 mg dose were rerandomized at a 1:1 ratio to simvastatin 40 or 80 mg in the extension. RESULTS: There was a significant advantage in the LDL cholesterol-lowering effect of the 80 mg dose compared with that of the 40 mg dose, which was maintained over the 48 weeks of treatment. The mean percentage reductions (95% confidence intervals) from baseline in LDL cholesterol for the 40 and 80 mg groups were 41% (42, 39) and 47% (48, 46), respectively, for the 24-week base study, and 41% (43, 39) and 46% (47, 45), respectively, after 48 weeks of treatment (p < 0.001 between groups). Larger reductions in total cholesterol and triglycerides were also observed with the 80 mg dose compared with the 40 mg dose at Weeks 24 and 48. Both doses were well tolerated, with close to 95% of patients enrolled completing the entire 48 weeks of treatment. Myopathy (muscle symptoms plus creatine kinase increase > 10 fold upper limit of normal) and clinically significant hepatic transaminase increases (> 3 times the upper limit of normal) occurred infrequently with both doses. There was no significant difference between the groups in the number of patients with such increases, although there were more cases for both with the 80 mg dose. CONCLUSIONS: Compared with the 40 mg dose, simvastatin 80 mg produced greater reductions in LDL cholesterol, total cholesterol, and triglycerides. Both doses were well tolerated.

Adult↗

Paraoxonase gene polymorphisms are associated with carotid arterial wall thickness in subjects with familial hypercholesterolemia.

Human serum paraoxonase (PON) is a high density lipoprotein (HDL) associated enzyme capable of hydrolyzing lipid peroxides in vitro. PON has recently attracted attention as a protective factor against oxidative modification of LDL and may therefore play an important role in the prevention of the atherosclerotic process. Two frequent mutations at the paraoxonase gene locus (PON1) are the leucine (L allele)-->methionine (M allele) and the glutamine (Q allele)-->arginine (R allele) substitutions at residues 55 and 192, respectively. We have examined the influence of these two polymorphisms on carotid atherosclerosis in familial hypercholesterolemia (FH) patients. The allele frequencies of these two polymorphisms were determined by PCR and restriction fragment analysis, for both the FH population and healthy controls. High resolution B-mode ultrasound was used to assess intima-media wall thickness (IMT) of the carotid artery. No differences were found in allele frequencies between the FH and the control population. In FH patients, the LL, LM and MM genotypes at position 55 occurred in 86 (46.0%), 78 (41.7%) and 23 (12.3%) subjects, respectively, whereas the QQ, QR and RR genotypes at position 192 were found in 90 (48.1%), 79 (42.2%) and 18 (9.6%) individuals. When both polymorphisms were considered separately, no different carotid IMTs were found between the genotype groups. However, our data did show a significant association between the various genotypes of the combined polymorphisms at position 55 and 192 of PON1 and the carotid artery IMT in FH subjects. Subjects with the homozygous wildtype LL/QQ for paraoxonase had the highest mean carotid IMTs when compared to other genotypes, combined. Multiple regression analysis demonstrated age (beta=0.34, P<0.0001), total plasma cholesterol (beta=0.17, P=0. 0109) and the LL/QQ genotype of the PON1 gene (beta=0.22, P=0.0018) to be significant risk factors for carotid atherosclerosis in subjects with FH. The LL/QQ genotype could explain 5.3% of total variance of carotid IMT. In conclusion, this is the first study to report an independent association between the combined PON1 polymorphism genotypes and carotid wall thickness. The homozygous wildtype LL/QQ for PON1 may represent an additional risk factor for carotid atherosclerosis in subjects with FH.

Adult↗

Additional risk factors influence excess mortality in heterozygous familial hypercholesterolaemia.

Life expectancy of patients with familial hypercholesterolaemia is decreased. Some untreated patients reach a normal life span and, therefore, additional risk factors and the type of mutation in the low-density lipoprotein (LDL) receptor gene are likely to influence the clinical outcome. We determined all cause mortality in kindreds with the disorder, who were untreated, in order to study (a) additional risk factors for coronary artery disease (CAD) and (b) the types of LDL receptor gene mutations that may contribute to a poor prognosis. The mortality in all 855 first-degree relatives of 113 unrelated patients was compared to the Dutch population after standardisation for age, gender, and calendar period. Analyses restricted to affected relatives could have underestimated the mortality risk due to lack of information about severe cases, who died prematurely. Therefore, all first-degree relatives were analysed and as a result the standardised mortality ratios (SMRs) exhibit only 50% of the excess mortality from familial hypercholesterolaemia. We observed 190 deaths in 32048 person-years leading to an overall SMR of 1.34 (95% confidence interval (CI) 1. 16-1.55, P=0.001). High excess mortality occurred in males between age 40 and 54 (SMR 2.34, 95% CI 1.60-3.31, P<0.001). The excess mortality decreased during the last decades. This change of mortality over calendar time shows that additional risk factors modulate the mortality from the disorder. The SMR of 62 families referred with premature CAD was 1.62 (95% CI 1.32-1.93, P<0.001) and the SMR was 1.10 (95% CI 0.86-1.34, P=0.4) in 51 families without premature CAD. The mortality risk of kindreds with null alleles was similar to that of kindreds with other mutations. In conclusion, the burden of the untreated disorder occurred mainly among middle-aged males and was not influenced by the type of mutation. Additional risk factors increased excess mortality significantly and are highlighted by the presence of premature CAD among first-degree relatives. This underscores the need for active identification of all hypercholesterolaemic relatives of such patients.

Adolescent↗

The V73M mutation in the hepatic lipase gene is associated with elevated cholesterol levels in four Dutch pedigrees with familial combined hyperlipidemia.

Familial combined hyperlipidemia (FCHL) is a heritable lipid disorder characterized by multiple lipoprotein phenotypes within a single family. Previously, we have shown an increased incidence of mutations in the LPL gene which was associated with elevated levels of very low density lipoprotein (VLDL) and decreased levels of high density lipoprotein among the families studied. Now, we report the results of our study on the hepatic lipase gene. We found the HL V73M variant to be present in four FCHL families. By means of a pedigree-based maximum log-likelihood method we analyzed the effect of this variant on the lipid levels in these families. Carriers of the HL V73M variant revealed significantly higher levels of total cholesterol (P < 0.01) and apoB (P <0.01). These findings show that the HL V73M mutant explains another part of the variability in the phenotype observed among FCHL family members, compared with mutations in the LPL gene. Family analysis shows that in these FCHL families, carriers of mutations in the LPL or HL genes have an increased risk for FCHL compared with their non-carrier relatives.

Adult↗

Molecular genetic testing for familial hypercholesterolemia: spectrum of LDL receptor gene mutations in The Netherlands.

Mutations in the LDL receptor are responsible for familial hypercholesterolemia (FH). At present, more than 600 mutations of the LDL receptor gene are known to underlie FH. However, the array of mutations varies considerably in different populations. Therefore, the delineation of essentially all LDL receptor gene mutations in a population represents a prerequisite for the implementation of nation-wide genetic testing for FH. In this study, the frequency and geographical distribution of 13 known mutations were evaluated in a cohort of 1223 FH patients. We identified 358 mutation carriers, representing 29% of the FH cohort. Four mutations (N543H-2393de19, 1359--1G-->A, 313 + 1 G-->A and W23X) occurred with a relatively high frequency, accounting for 22.4% of the entire study cohort. Two of these common FH mutations (N543H-2393de19 and 1359 - 1G-->A) showed a preferential geographic distribution. Second, to further expand the array of LDL receptor gene mutations, we conducted mutation analysis by denaturing gradient gel electrophoresis (DGGE) in 141 children with definite FH. A mutation was identified in 111 patients, involving 16 new single base substitutions and four small deletions and insertions, which brings the number of different FH-causing mutations in our country up to 61. Our data indicate that an estimate of the prevalence of specific mutations, as well as the compilation of a database of all FH-causing mutations in a given country, can facilitate selection of the most appropriate molecular diagnostic approach.

Child↗

The effect of cholesterol lowering on carotid and femoral artery wall stiffness and thickness in patients with familial hypercholesterolaemia.

BACKGROUND: Early in the process of atherosclerosis, changes in vessel wall stiffness and thickness may occur. The present study evaluates the effect of cholesterol reduction on artery wall stiffness and intima media thickness in patients with familial hypercholesterolaemia (FH). MATERIALS AND METHODS: Forty-five patients with familial hypercholesterolaemia (mean age 46+/-10 years) with untreated LDL cholesterol concentration > 9 mmol L(-1), were studied before and after one year of cholesterol lowering therapy with statins (simvastatin, atorvastatin 40-80 mg day(-1). The distensibility (DC in 10-3 kPa(-1) and compliance (CC in mm2. kPa(-1) of the common carotid artery (CCA) (right and left side) and common femoral artery (CFA) (right side) were determined by a wall track system (Pie Medical). The intima media thickness (IMT) (both right and left) of the CCA, bulb (BUL), internal carotid artery (ICA) and CFA were measured in mm by high-resolution ultrasound (Biosound). RESULTS: The mean concentration of total cholesterol (TC), LDL-cholesterol (LDL-C) and triglycerides (TG) were reduced significantly by 43%, 51% and 25%, respectively, whereas HDL-cholesterol (HDL-C) increased by 13% (P<0.001). In the CFA, the DC and CC increased significantly (DC from 7.9+/-3.0 to 9.1+/-3.7 in 10(-3) kPa(-1); CC 0.5+/-0.2-0.6+/-0.3 in mm2. kPa(-1), whereas the DC and CC did not change in the CCA. In contrast, the IMT of the CCA decreased significantly in both men and women whereas an IMT decrease was also seen in the BUL and ICA in premenopausal women. A LDL-cholesterol reduction of 44.8% and 45.4% was necessary to induce significant decreases in IMT and increases in DC and CC. CONCLUSIONS: One year of cholesterol lowering therapy in FH decreases the wall stiffness in the CFA and the arterial wall thickness in the CCA.

Adult↗

Cholesterol efflux regulatory protein, Tangier disease and familial high-density lipoprotein deficiency.

Cellular cholesterol efflux, by which cholesterol is transported from peripheral cells to HDL acceptor molecules for transport to the liver, is the first step of reverse cholesterol transport. Two genetic disorders, Tangier disease and some cases of familial HDL deficiency, have defects of cellular cholesterol efflux. The recent discovery of mutations in the ABC1 gene, which encodes the cholesterol efflux regulatory protein, in both these disorders establishes cholesterol efflux regulatory protein as a rate-limiting factor in reverse cholesterol transport.

ATP Binding Cassette Transporter 1↗

Tailored therapy to fit individual profiles. Genetics and coronary artery disease.

In the twentieth century, coronary artery disease (CAD) was the major cause of morbidity and mortality in western societies. Genetics and environmental influences clearly contribute to CAD. Our genetic makeup contributes to not only coronary risk factors, but also determines an individual's response to environmental challenges such as diet, drugs, and tobacco. Genetic testing is likely to be more predictive of our predisposition to CAD than current conventional testing of known risk factors. Therapy aimed at altering the regulation of genes or their transcribed proteins may prove appropriate in individual patients, depending on their genetic background. The understanding of our genetic predisposition to CAD may enable targeted environmental modification strategies aimed at individuals at greatest risk. Both in terms of the huge costs of drugs to society and in terms of needless medicalization, genotyping in order to tailor therapy might become a routine part of risk management earlier than we think.

Angioplasty, Balloon, Coronary↗

Plasma and vessel wall lipoprotein lipase have different roles in atherosclerosis.

Lipoprotein lipase (LPL) is a key enzyme in lipoprotein metabolism, and has been hypothesized to exert either pro- or anti-atherogenic effects, depending on its localization. Decreased plasma LPL activity is associated with the high triglyceride (TG);-low HDL phenotype that is often observed in patients with premature vascular disease. In contrast, in the vessel wall, decreased LPL may be associated with less lipoprotein retention due to many potential mechanisms and, therefore, decreased foam cell formation. To directly assess this hypothesis, we have distinguished between the effects of variations in plasma and/or vessel wall LPL on atherosclerosis susceptibility in apoE-deficient mice. Reduced LPL in both plasma and vessel wall (LPL(+/-)E(-/-)) was associated with increased TG and increased total cholesterol (TC) compared with LPL(+/+)E(-/-) sibs. However despite their dyslipidemia, LPL(+/-)E(-/-) mice had significantly reduced lesion areas compared to the LPL(+/+)E(-/-) mice. Thus, decreased vessel wall LPL was associated with decreased lesion formation even in the presence of reduced plasma LPL activity. In contrast, transgenic mice with increased plasma LPL but with no increase in LPL expression in macrophages, and thus the vessel wall, had decreased TG and TC and significantly decreased lesion areas compared with LPL(+/+)E(-/-) mice. This demonstrates that increased plasma LPL activity alone, in the absence of an increase in vessel wall LPL, is associated with reduced susceptibility to atherosclerosis. Taken together, these results provide in vivo evidence that the contribution of LPL to atherogenesis is significantly influenced by the balance between vessel wall protein (pro-atherogenic) and plasma activity (anti-atherogenic).

Animals↗

Mutations in the ABC1 gene in familial HDL deficiency with defective cholesterol efflux.

BACKGROUND: A low concentration of HDL cholesterol is the most common lipoprotein abnormality in patients with premature atherosclerosis. We have shown that Tangier disease, a rare and severe form of HDL deficiency characterised by a biochemical defect in cellular cholesterol efflux, is caused by mutations in the ATP-binding-cassette (ABC1) gene. This gene codes for the cholesterol-efflux regulatory protein (CERP). We investigated the presence of mutations in this gene in patients with familial HDL deficiency. METHODS: Three French-Canadian families and one Dutch family with familial HDL deficiency were studied. Fibroblasts from the proband of each family were defective in cellular cholesterol efflux. Genomic DNA of each proband was used for mutation detection with primers flanking each exon of the ABC1 gene, and for sequencing of the entire coding region of the gene. PCR and restriction-fragment length polymorphism assays specific to each mutation were used to investigate segregation of the mutation in each family, and to test for absence of the mutation in DNA from normal controls. FINDINGS: A different mutation was detected in ABC1 in each family studied. Each mutation either created a stop codon predicted to result in truncation of CERP, or altered a conserved aminoacid residue. Each mutation segregated with low concentrations of HDL-cholesterol in the family, and was not observed in more than 500 control chromosomes tested. INTERPRETATION: These data show that mutations in ABC1 are the major cause of familial HDL deficiency associated with defective cholesterol efflux, and that CERP has an essential role in the formation of HDL. Our findings highlight the potential of modulation of ABC1 as a new route for increasing HDL concentrations.

ATP Binding Cassette Transporter 1↗

Effects of oral folic acid supplementation on endothelial function in familial hypercholesterolemia. A randomized placebo-controlled trial.

BACKGROUND: Folates have been suggested to be of benefit in reducing cardiovascular risk. The present study was designed to examine whether oral folic acid supplementation could improve endothelial function as an intermediate end point for cardiovascular risk in patients with increased risk of atherosclerosis due to familial hypercholesterolemia (FH). METHODS AND RESULTS: In a prospective, randomized, double-blind, placebo-controlled study with crossover design, we evaluated the effects of 4 weeks of treatment with oral folic acid (5 mg PO) on endothelial function in FH. In 20 FH patients, forearm vascular function was assessed at baseline, after 4 weeks of folic acid treatment, and after 4 weeks of placebo treatment by venous occlusion plethysmography, with serotonin and sodium nitroprusside used as endothelium-dependent and -independent vasodilators. In addition, we examined the vasoconstrictor response to the NO synthase inhibitor N(G)-monomethyl-L-arginine to assess basal NO activity. In FH patients, folic acid supplementation restored the impaired endothelium-dependent vasodilation, whereas it did not significantly influence endothelium-independent vasodilation or basal forearm vasomotion. There was a trend toward improvement in basal NO activity. CONCLUSIONS: These data demonstrate that oral supplementation of folic acid can improve endothelial function in patients with increased risk of atherosclerotic disease due to hypercholesterolemia, without changes in plasma lipids.

Administration, Oral↗