Randomized controlled trial on efficacy of oligomeric formula (HINE E-GEL®) versus polymeric formula (MEIN®) enteral nutrition after esophagectomy for esophageal cancer with gastric tube reconstruction

The efficacy of early enteral nutrition after esophageal cancer surgery has been reported. However, the choice of formula and management of diarrhea are important to achieve the goal of enhanced recovery after surgery. The aim of this study is to assess the frequency of diarrhea/completion rate of enteral nutrition regimen as primary endpoints and the postoperative nutritional status/body composition analysis/operative morbidity as secondary endpoints was compared between the two nutrition groups. Among the 122 patients who underwent esophagectomy for esophageal cancer between December 2015 and September 2017, 67 patients who met the eligibility criteria were randomly assigned to receive enteral nutrition with either HINE E-GEL® (HINE group; n = 33) or MEIN® (MEIN group; n = 34). The incidence of diarrhea was significantly lower in the HINE group (18.2 % vs. 64.7 %, P < 0.001). The score of Bristol scale of POD 6/7 was significantly lower in the HINE group (P = 0.019/P = 0.006, respectively). The completion rate of enteral nutrition regimen was significantly higher in the HINE group (97.4 % vs. 86.6 %, P = 0.002). The Controlling Nutritional Status scores and total protein levels at 6 months after surgery were significantly better in the HINE group (P = 0.030 and P = 0.023, respectively), indicating improved tendency in nutritional status in the HINE group. However, there were no significant differences in Prognostic Nutritional Index values, blood test results, rapid turnover proteins, body mass index, or body composition between the two groups. HINE E-GEL compared with MEIN may reduce the frequency of diarrhea, enabling patients to adhere to the scheduled enteral nutrition plan. Also, maintenance of nutritional status with HINE E-GEL was comparable or potentially better in some nutrition components to that with MEIN, indicating that HINE E-GEL can be an option for enteral nutrition following esophageal surgery to achieve the goal of successful completion of scheduled enteral nutrition and smooth transition to the normal diet.

Histopathologic findings in patients with idiopathic megacolon: a comparison between dilated and non-dilated loops

BACKGROUND

Idiopathic megacolon (IMC) is an intractable motility disorder in which chronic symptoms of colonic dysmotility appear with no mechanical cause. Although a pathological analysis is essential to understand the mechanism of IMC, no study has compared the histopathologic findings between dilated and non-dilated loops in IMC cases, and little is known about the proportion of each disease subtype.

METHODS

Fifty-three full-thickness samples (dilated loops, n = 31; non-dilated loops, n = 22) from 31 IMC cases and 16 samples (dilated loops; n = 8, non-dilated loops; n = 8) from eight controls were collected. All the samples were stained with hematoxylin-eosin (HE), Hu C/D antibody, and CD117 antibody to assess degenerative myopathy, degenerative neuropathy, inflammatory neuropathy, hypoganglionosis, and mesenchymopathy according to the London Classification. Findings of the dilated and non-dilated loop samples were compared, and the proportions of each subtype were analyzed.

KEY RESULTS

Based on a control study, <60 ganglion cells/cm was defined as hypoganglionosis in our series. Myopathy was observed in 11 patients (35.5%), neuropathy was in 19 patients (61.3%), and mesenchymopathy was in 10 patients (32.2%). An overlap between subtypes was observed in some cases. Surprisingly, the non-dilated loop samples exhibited very similar histopathologic abnormalities to those observed in the dilated loop samples in most cases.

CONCLUSIONS & INFERENCES

Our study is the first to compare the histopathologic findings between dilated and non-dilated loops in IMC patients. Histopathologic abnormalities precede the clinical manifestation of IMC, and may consequently lead to gradual colonic dilatation; however, detailed mechanism including dilation triggering factor needs further elucidation.

Methylation of the oestrogen receptor gene in non-neoplastic epithelium as a marker of colorectal neoplasia risk in longstanding and extensive ulcerative colitis

BACKGROUND

Surveillance colonoscopy is widely recommended in patients with longstanding and extensive ulcerative colitis (UC) in order to detect colorectal neoplasia at an early stage. However, it still remains questionable whether surveillance colonoscopy effectively enables early detection of UC associated neoplasia. There is a great need for sensitive markers to identify individuals at increased risk of neoplasia. The oestrogen receptor (OR) gene shows age related methylation in the colorectal epithelium and is methylated frequently in sporadic colorectal neoplasia, suggesting that OR methylation may predispose to colorectal neoplasia.

AIM

To clarify whether analysis of methylation of the OR gene in non-neoplastic epithelium can contribute to prediction of increased neoplasia risk in UC patients.

MATERIALS AND METHODS

A total of 165 non-neoplastic colorectal epithelia from 30 patients with longstanding and extensive UC, including 13 UC patients with neoplasia and 17 patients without, were evaluated. Methylation specific polymerase chain reaction was performed to determine the methylation status of the OR gene.

RESULTS

Methylation of the OR gene was detected in 54 of 70 (77.1%) non-neoplastic colorectal epithelia in UC with neoplasia but in only 23 of 95 (24.2%) without neoplasia. Methylation of the OR gene was significantly more frequent in non-neoplastic epithelium from UC with neoplasia than in chronic colitic epithelium from UC without neoplasia. Furthermore, in UC with neoplasia, the OR gene was extensively methylated in non-neoplastic epithelia throughout the colorectum compared with those in UC without neoplasia.

CONCLUSION

These results suggest that analysis of OR gene methylation may have potential as a useful marker for identifying individuals at increased risk of neoplasia among those with longstanding and extensive UC.

A MEK inhibitor (U0126) markedly inhibits direct liver invasion of orthotopically inoculated human gallbladder cancer cells in nude mice

Primary cancer of the gallbladder is not unusual. Most cases of gallbladder cancer are found at an advanced stage, accompanied by the invasion to the liver, metastases to the lymph nodes and distant organs, and peritoneal dissemination. In this study, we first examined the effect of mitogen-activated protein kinase kinase (MEK) inhibitors on the production of matrix metalloproteinases (MMPs), urokinase-type plasminogen activator (uPA), and tissue inhibitors of metalloproteinases (TIMPs) in a human gallbladder cancer cell line, NOZ cells in vitro. MEK inhibitors (PD98059 and U0126) inhibited the production of MMP-2, MMP-9 and high MW uPA, and upregulated TIMPs (TIMP-1, TIMP-2 and TIMP-3). Subsequently, we examined the effect of U0126 on invasion and metastasis of orthotopically inoculated NOZ cells in nude mice. Direct liver invasion by cancer cells was detected in all of the mice in the control group, but in only one mouse in the U0126-treated group. Most of the primary tumors in the U0126-treated group expanded to the liver, but did not invade into the liver. Vessel invasion in the liver was evident in 4 out of 5 mice in the control group, but in only one mouse in the U0126-treated group. Lymph node metastases and peritoneal dissemination were recognized in all of the mice in both groups. All 5 mice in the U0126-treated group, and 4 out of 5 mice in the vehicle control group, had metastases in the lungs. The present results suggest that a MEK inhibitor, U0126, prolonged the survival of the mice with NOZ tumor by inhibiting direct liver invasion and vessel invasion of the cancer cells via down-regulation of the matrix degrading ability of the cancer cells.

Development of colonic neoplasia in p53 deficient mice with experimental colitis induced by dextran sulphate sodium

BACKGROUND

Several animal models for human ulcerative colitis (UC) associated neoplasia have been reported. However, most neoplasias developed in these models have morphological and genetic characteristics different from UC associated neoplasia.

AIMS

To establish a new colitis associated neoplasia model in p53 deficient mice by treatment with dextran sulphate sodium (DSS).

METHODS

DSS colitis was induced in homozygous p53 deficient mice (p53(-/-)-DSS), heterozygous p53 deficient mice (p53(+/-)-DSS) and wild-type mice (p53+/+-DSS) by treatment with 4% DSS. Numbers of developed neoplasias were compared among the experimental groups, and macroscopic and microscopic features of the neoplasias were analysed. Furthermore, K-ras mutation and beta-catenin expression were assessed.

RESULTS

p53(-/-)-DSS mice showed 100% incidence of neoplasias whereas the incidences in p53(+/-)-DSS and p53+/+-DSS mice were 46.2% and 13.3%, respectively. No neoplasias were observed in the control groups. The mean numbers of total neoplasias per mouse were 5.0 (p53(-/-)-DSS), 0.62 (p53(+/-)-DSS), and 0.2 (p53+/+-DSS). The number of neoplasias per mouse in the p53(-/-)-DSS group was significantly higher than that in the other DSS groups. The incidences of superficial type neoplasias were 91.7% in p53(-/-)-DSS mice, 75.0% in p53(+/-)-DSS mice, and 33.3% in p53+/+-DSS mice. The K-ras mutation was not detected in any of the neoplasias tested. Translocation of beta-catenin from the cell membrane to the cytoplasm or nucleus was observed in 19 of 23 (82.6%) neoplasias.

CONCLUSIONS

The p53(-/-)-DSS mice is an excellent animal model of UC associated neoplasia because the morphological features and molecular genetics are similar to those of UC associated neoplasia. Therefore, this model will contribute to the analysis of tumorigenesis related to human UC associated neoplasia and the development of chemopreventive agents.

Combination cancer chemoprevention with green tea extract and sulindac shown in intestinal tumor formation in Min mice

Green tea is the most effective beverage for cancer prevention in humans. Looking at the concept of combination cancer chemoprevention, we previously reported the synergistic effects of (-)-epigallocatechin gallate (EGCG) with sulindac, and the additive effects of EGCG with tamoxifen, on cancer-preventive activity in human lung cancer cell line PC-9. This paper reports confirmation of the synergistic effects of EGCG with sulindac on the inhibition of intestinal tumors in multiple intestinal neoplasia (Min) mice. Treatment with both green tea extract and sulindac significantly reduced the number of tumors from 72.3 +/- 28.3 to 32.0 +/- 18.7 tumors per mouse, a decrease of 44.3%, whereas treatment with green tea extract alone or with sulindac alone reduced it to 56.7 +/- 3.5 and 49.0 +/- 12.7, respectively. The results also indicated that green tea extract inhibited tumor growth in Min mice almost as potently as sulindac itself did. The three treated groups did not show any adenocarcinomas, whereas 10.8% of the control group did. Since cancer-preventive agents like sulindac and tamoxifen are associated with adverse effects, we discuss the possibility of non-toxic, combination cancer chemoprevention with green tea, looking at the goal of truly effective cancer prevention.

Heterogeneous nuclear ribonucleoprotein B1 expressed in esophageal squamous cell carcinomas as a new biomarker for diagnosis

We recently reported that heterogeneous nuclear ribonucleoprotein (hnRNP) B1 was overexpressed in most human lung cancers, especially squamous cell carcinoma (SCC), as well as human oral SCC. To find the significance of hnRNP B1 in cancer diagnosis, we studied hnRNP B1 expression in 16 paraffinized sections of esophageal SCC, using immunohistochemical staining with anti-hnRNP B1 polyclonal antibody, raised in a rabbit. We compared the expression of hnRNP B1 in cancerous and noncancerous regions of the same specimen: enhanced expression was observed in 63% of cancerous regions (10 / 16), whereas none of the noncancerous regions showed enhanced expression. The enhanced expression of hnRNP B1 in cancerous regions was compared with that in noncancerous tissue in relation to histopathological grade: 83% for well differentiated (5 / 6), 83% for moderately differentiated (5 / 6) and 0% for poorly differentiated (0 / 4). Histologically, enhanced expression of hnRNP B1 was observed around cancer pearls, as well as in the cells of nests lacking keratinization in well and moderately differentiated SCC. Western blotting analysis revealed enhanced expression in three frozen specimens of moderately differentiated SCC. Using esophageal cancer cell lines, we further confirmed the decreased expression in poorly differentiated SCC cells, compared with other differentiation types. All our results support the significance of hnRNP B1 expression in esophageal SCC as a unique diagnostic marker with regard to association between expression level and histopathological grading.

alpha6 integrin expression in esophageal carcinoma

One of the genes that the authors have isolated by a differential display of hepatocellular carcinoma compared to adjacent liver is the alpha6 integrin. alpha6 integrin is the major adhesion receptor for laminin and is suggested to be involved in tumor cell invasion and metastasis. To our knowledge, however, there are no reports on alpha6 integrin expression in esophageal carcinoma. We thus conducted a study to determine its clinicopathologic significance in human esophageal carcinoma. The tumor/normal (T/N) ratio of alpha6 integrin expression was calculated by Northern hybridization in 45 cases of esophageal carcinoma. In selected cases the expression of the alpha6 integrin variants A and B was also investigated by reverse transcriptase-polymerase chain reaction, and immunostaining for alpha6 integrin was performed. The expression levels of alpha6 integrin mRNA in the tumor tissue were greater than those of the corresponding normal tissue in 39 of 45 cases (87%). The overexpression of alpha6 integrin was also recognized by immunostaining. Fifteen cases with a high T/N ratio demonstrated a deeper invasion into the esophageal wall than the 30 cases with a low T/N ratio. Although there was no significant difference, the 15 cases with a high T/N ratio had a tendency for a worse prognosis. The ratio of the two variants (alpha6A/alpha6B) did not show any relationship to survival. The findings imply that alpha6 integrin is overexpressed in human esophageal carcinomas and that alpha6 integrin may play an important role in esophageal tumor invasion.

Frequent allelic imbalance on chromosome 18q21 in early superficial colorectal cancers

Genetic alterations in early superficial colorectal cancers have rarely been reported. In the present study, we searched for alterations in the APC and p53 genes in 27 superficial (20 depressed and 7 elevated) and 21 protruding colorectal cancers with submucosal invasion by means of PCR-single strand conformation polymorphism. Allelic imbalance (AI) on five loci, i.e., 1p34-36, 8p21-22, 14q32, 18q21 and 22q12-13, was also analyzed. Since a high incidence of 18q21 AI was detected in the superficial depressed cases, we further screened for alterations in Smad2, Smad4 and DCC. APC alterations were observed in three superficial depressed, one superficial elevated, and 11 protruding colorectal cancers, indicating that the frequency of APC alterations in superficial depressed cases was significantly lower than that in the protruding ones. There was no significant association between p53 alterations and macroscopic types. AI on 18q21 (13/20, 65%) was much higher than those on the other four loci in the superficial depressed cases. Moreover, the frequency of 18q21 AI in the superficial depressed cases was significantly higher than that in the protruding ones. Smad4 alterations were only detected in 1 of the 13 superficial depressed and 3 of the 17 protruding cases, while Smad2 and DCC alterations were not detected in any case examined. These data suggest that the carcinogenetic pathways of protruding and superficial depressed colorectal cancers are different, and that alterations of tumor suppressor gene(s) located on 18q21 other than Smad2, Smad4 and DCC might be associated with most superficial depressed colorectal cancers.

Abnormal fatty acid metabolism in patients with coronary vasospasm

Although various noninvasive methods have been used to detect vasospasm, none of them are sensitive enough for patients with sporadic attacks. Since abnormal fatty acid metabolism is observed in ischemic myocardium, 123I-beta-methyl-p-iodophenyl pentadecanoic acid (BMIPP), a radiolabeled fatty acid analog, has recently been proposed as a useful tracer for detecting myocardial damage. The aim of this study was to clarify the clinical implications of decreased myocardial BMIPP uptake in patients with vasospastic angina. We evaluated 53 patients with vasospastic angina (32 with clinically documented vasospasm [Group-A] and 21 with vasospasm induced by ergonovine provocation [Group-B]) and 27 control subjects, 20 in Group-A were re-evaluated 6 months after medical treatment. The territorial regions of vasospasm-induced coronary artery, the wall motion by left ventriculography, and BMIPP uptake were compared. Vasospasm was induced in multiple coronary arteries in 29 (55%) patients. Reduced wall motion and decreased BMIPP uptake were observed in 19 (36%) patients and 47 (89%) patients, respectively. The sensitivity and specificity of determination of vasospasm-induced coronary arteries with BMIPP scintigraphy were 71% (69/97 coronary arteries) and 88% (126/143), respectively. Vasospasm was re-induced by ergonovine provocation in 8 patients (Group-I) and not re-induced in 12 (Group-II) after treatment. In Group-I, improvement of decreased BMIPP uptake was lower than in Group-II (19+/-11 vs. 59+/-22%, mean+/-SD, p < 0.001). The regions in which vasospasm was re-provoked exhibited decreased BMIPP uptake. Abnormal fatty acid metabolism was more often observed than wall motion abnormality in the vasospastic region in patients with vasospastic angina. BMIPP scintigraphy is a highly accurate and non-invasive technique for determining the presence and location of vasospasm.

Myocardial CD36 expression and fatty acid accumulation in patients with type I and II CD36 deficiency

Long-chain fatty acids (LCFA) are one of the major cardiac energy substrates, so understanding LCFA metabolism may help in elucidating the mechanisms of various heart diseases. CD36 is a multifunctional membrane glycoprotein that acts not only as a receptor for thrombospondin, collagen and oxidized low density lipoprotein but also as a receptor for LCFA. We investigated the relationship between CD36 expression in myocardial capillary endothelial cells and myocardial LCFA uptake in patients with CD36 deficiency. We analyzed CD36 expression in blood cells from 250 patients with heart diseases by means of a flow cytometer. In 218 patients, myocardial LCFA scintigraphy was performed with 123I-beta-methyl-p-iodophenyl pentadecanoic acid (BMIPP). In 5 patients, myocardial capillary endothelial cells were examined immunohistochemically for CD36 expression. Eleven patients (4%) showed signs of type I CD36 deficiency (neither platelets nor monocytes expressed CD36). Twenty patients (8%) had type II CD36 deficiency (monocytes expressed CD36 but platelets did not). In all 11 patients with type I CD36 deficiency, no BMIPP accumulation was observed in the heart, but in 13 patients with type II CD36 deficiency, BMIPP accumulation in the heart was focally reduced, but there were no patients without BMIPP accumulation in the heart. Although the myocardial capillary endothelial cells from two CD36-positive patients expressed CD36, those from two patients with type I CD36 deficiency did not. In a patient with type II CD36 deficiency, some capillary endothelial cells displayed patchy CD36 expression. CD36 deficiency was documented in 31 (12%) patients with heart diseases. Because CD36 was not expressed in the myocardial capillary endothelial cells in patients with type I CD36 deficiency, type I CD36 deficiency is closely related to lack of myocardial LCFA accumulation and metabolism in the myocardium.

Hypertrophic cardiomyopathy with type I CD36 deficiency

CD36 is a multifunctional membrane-type receptor glycoprotein that reacts with oxidized low-density lipoprotein and long-chain fatty acid (LCFA). A patient presented with hereditary hypertrophic cardiomyopathy (HCM) and type I CD36 deficiency (neither platelets nor monocytes expressed CD36) but showed no myocardial LCFA accumulation. CD36 was expressed in the capillary endothelial cells of the cardiac muscle of a control subject, while the patient's myocardial capillary endothelial cells were completely CD36-negative. These results suggest that type I CD36 deficiency is closely related to hereditary HCM and lack of myocardial LCFA accumulation.

[Histopathological study of the role of Helicobacter pylori in the occurrence and development of chronic active gastritis, acute erosive gastritis and gastric ulcer]

A total of 773 gastric mucosas taken from 653 patients who were endoscopically diagnosed as normal, or having reddening, irregular mucosa, erosion, small ulcer or scar were examined pathologically according to the Sydney system to study the role of H. pylori in the occurrence and development of chronic active gastritis, acute erosive gastritis and ulcer. H. pylori were detected in higher frequency in lesions showing active inflammation with neutrophil infiltration and necrosis of the mucosa. The presence of H. pylori was correlated with the degree of lymphocyte infiltration, but not with the degree of intestinal metaplasia, mucosal atrophy and location in the stomach. Reddening and irregular mucosas were found histologically to be chronic active gastritis. These results suggested that H. pylori causes active inflammation in the gastric rucosa, and that milder inflammation causes reddening or irregularity of the mucosa, whereas severer inflammation causes erosion and ulcer. There is no essential difference between chronic active and acute erosive gastritis.

Reduction of plasma cholesterol levels and induction of hepatic LDL receptor by cerivastatin sodium (CAS 143201-11-0, BAY w 6228), a new inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, in dogs

The effects of cerivastatin sodium (BAY w 6228), a new type of inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, on plasma cholesterol concentrations and the induction of hepatic LDL receptors were investigated with beagle dogs and Hep G2 cells. Oral administration of cerivastatin (0.01, 0.03, and 0.1 mg/kg per day) for 3 weeks reduced plasma total and very low-density lipoprotein plus low-density lipoprotein (VLDL + LDL) cholesterol concentrations and increased hepatic LDL receptor binding activity in dogs. Scatchard plot analysis revealed a 1.9-fold increase in the maximum binding capacity of hepatic LDL receptors in cerivastatin-treated animals. Similar results were obtained by administration of pravastatin (1.0 and 5.0 mg/kg/day) for 3 weeks. Binding activity of the LDL receptor, as well as receptor mRNA and protein concentrations, were increased in a dose-dependent manner (0.01-1.0 microM) by exposure of Hep G2 cells to cerivastatin. The results suggest that cerivastatin reduces plasma cholesterol concentrations by increasing hepatic LDL receptor expression. The mechanism of lowering cholesterol concentration by cerivastatin was the same as with the other previously examined HMG-CoA reductase inhibitors, but the effects with cerivastatin were apparent at doses much lower than the effective doses of the other drugs. Cerivastatin, therefore, shows potential for clinical use as a potent and efficacious plasma cholesterol-lowering drug.

Analyses of the APC and TGF-beta type II receptor genes, and microsatellite instability in mucosal colorectal carcinomas

APC and transforming growth factor-beta type II receptor (TGF-beta RII) gene mutations, and microsatellite instability have been found in sporadic colorectal carcinomas. To clarify further the early alterations in colorectal carcinogenesis, we investigated these genetic changes in 23 protruding- and 24 superficial-type mucosal colorectal carcinomas. TGF-beta RII gene mutations and microsatellite instability were rarely found in these lesions. Nevertheless, APC was mutated in 16 of the 47 (34.0%) mucosal colorectal carcinomas and was significantly more frequently mutated in protruding- (I) and superficial elevated-type (IIa) (14/32, 43.8%) than in other superficial-type (IIa+IIc, IIb, IIc, and IIc+IIa) (2/ 15, 13.3%) mucosal colorectal carcinomas (P < 0.04). These results indicate that the APC gene may be involved from the beginning in the tumorigenesis of many early colorectal carcinomas, particularly of the protruding and superficial elevated types. However, there might be a distinct pathway for other superficial-type colorectal carcinomas, possibly not involving APC as an initial step of tumorigenesis.

High-performance liquid chromatographic separation of kyotorphin, a basic Tyr-Arg dipeptide, in rat brain tissue and quantification using fluorimetric detection

Two HPLC procedures based on sample derivatization at the N-terminal Tyr moiety with agents yielding fluorescent derivatives were applied to the selective and sensitive detection as well as quantification of the basic kyotorphin, Tyr-Arg dipeptide, in rat brain tissue. The first one is a post-column fluorescence derivatization method, whereby the peptides extracted from the brain tissue are separated on an octadecylsilyl-silica gel column, followed by on-line fluorescence derivatization for detection. The other one is a pre-column derivatization method, where the extracted peptides are first reacted with fluorogenic agents at the N-terminal Tyr moiety to their corresponding fluorescent derivatives, subsequently separated on an octadecyl-poly(vinyl alcohol) copolymer gel column, and signal responses are measured fluorimetrically. Both methods permitted the quantification of the synthetic kyotorphin added to the rat brain tissues. The concentration range of kyotorphin-like biogenic peptide was 60-100 pmol/g in the cortex, striatum and hypothalamus tissues.

A combined assay of cell viability and in vitro cytotoxicity with a highly water-soluble tetrazolium salt, neutral red and crystal violet

Cell viability and in vitro cytotoxicity assay methods were developed using a combination of dyes, 4-[3-(4-iodophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1,3-benzene disulfonate (WST-1), neutral red (NR) and crystal violet (CV), with HeLa cells as a bioindicatior. As WST-1 produces a highly water soluble and non-cytotoxic formazan dye, ti allows each assay to be carried out in one culture dish. The combined cell viability assay using WST-1, NR and CV gave an absorbance that correlated linearly with the number of cells over the range 1000 to 50,000 cells/well. The combined assay was applied to the evaluation of IC50 values for sodium dodecyl sulfate as a model toxicant, which yielded similar values to those obtained with each assay independently.

2-(5-hydrazinocarbonyl-2-oxazolyl)-5,6-dimethoxybenzothiazole as a precolumn fluorescence derivatization reagent for carboxylic acids in high-performance liquid chromatography and its application to the assay of fatty acids in human serum

A unique acid hydrazide, 2-(5-hydrazinocarbonyl-2-oxazolyl)-5,6-dimethoxybenzothia zole, that is characterized by the benzothiazole structure conjugated to an oxazoline moiety was synthesized, and its applicability as a precolumn derivatization reagent for carboxylic acids in HPLC was examined in view of sensitivity and separability. The sensitivity of the hydrazide for carboxylic acids was determined using lauric acid to be 0.1 pmol (per 10-microliters injection volume) at a signal-to-noise ratio of 3. The reagent allowed rapid assays of carboxylic acids within 20 min with satisfactory separability. The method was applied to the determination of fatty acids in human sera from healthy volunteers as well as from patients with diabetes or thyroid dysfunction.

1,2-Diarylethylenediamines as sensitive pre-column derivatizing reagents for chemiluminescence detection of catecholamines in HPLC

Chemiluminescence detection in high-performance liquid chromatography for derivatives of catecholamines (norepinephrine, epinephrine and dopamine) and isoproterenol was studied on the basis of the peroxyoxalate chemiluminescence reaction. The amines and isoproterenol, derivatized with 1,2-diarylethylenediamines, were separated on a reversed-phase HPLC column (TSK gel ODS-120T) with isocratic elution using a mixture of imidazole buffer (pH 5.8, 120 mM)-methanol-acetonitrile (6:2:9, v/v/v). The eluate was detected by a post-column chemiluminescence reaction system, using bis[4-nitro-2-(3,6,9-trioxadecyloxycarbonyl)phenyl]oxalate and hydrogen peroxide. Of the 141,2-diarylethylenediamines investigated, it was found that 1,2-bis(3-chlorophenyl)ethylenediamine, 1,2-bis(3,4-dichlorophenyl)-ethylenediamine and 1,2-bis(4-chlorophyenyl)ethylenediamine were the most sensitive derivatives for all catecholamines. The derivatization and peroxyoxalate chemiluminescence reaction conditions were optimized for 1,2-bis(3-chlorophenyl)-ethylenediamine. The chromatographic detection limits for catecholamines were approximately 40-120 amol for an injection volume of 100 microliters (signal-to-noise ratio of 3).

Pharmacological properties of KT3-671, a novel nonpeptide angiotensin II receptor antagonist

We examined pharmacological profiles of KT3-671, 2-propyl-8-oxo-1-[(2'-(1H-tetrazole-5-yl) biphenyl-4-yl)methyl]- 4,5,6,7-tetrahydro-cycloheptimidazole, a newly synthesized nonpeptide angiotensin II (AII) receptor antagonist in various in vitro and in vivo studies. KT3-671 displaced specific binding of [125I]Sar1 Ile8-AII to AT1 receptor with a Ki value of 0.71 +/- 0.14 x 10(-9) M in rat liver membranes, but had no affinity for AT2 receptor in bovine cerebellar membranes (Ki > 10(-5) M). In isolated rabbit aorta, KT3-671 produced a parallel rightward shift in the concentration-response curve for AII with a pA2 value of 10.04 +/- 0.12, but had no effect on KCl-, norepinephrine (NE)-, and serotonin (5-HT)-induced contractions. In conscious normotensive rats, KT3-671 (0.3-10 mg/kg, p.o.) inhibited the AII-induced pressor response dose dependently. In renal artery-ligated hypertensive rats, KT3-671 (0.1-3 mg/kg, p.o.) decreased arterial blood pressure (BP) dose dependently. The hypotensive action of 3 mg/kg KT3-671 was maintained for at least 24 h. These results suggest that KT3-671 is a potent AT1 subtype-selective and competitive nonpeptide AII receptor antagonist and has an orally active antihypertensive effect without agonistic activity.

Effect of pravastatin, a 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitor, on hepatic cholesterol 7 alpha-hydroxylase, acyl-coenzyme A: cholesterol acyltransferase, and bile lipid secretion in the hamster with intact enterohepatic circulation

The effects of administration of pravastatin, a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, on hepatic cholesterol 7 alpha-hydroxylase and acyl-coenzyme A: cholesterol acyltransferase (ACAT) activities and bile lipid secretion were investigated in Syrian golden hamsters. Continuous administration of pravastatin induced no significant changes in hepatic cholesterol content, ACAT and cholesterol 7 alpha-hydroxylase activities, or bile lipid and acid composition. Abrupt withdrawal of pravastatin induced increases in hepatic cholesterol content and ACAT activity and no change in hepatic cholesterol 7 alpha-hydroxylase activity, and increased cholesterol saturation in bile. Hepatic cholesterol 7 alpha-hydroxylase activity paralleled hepatic mRNA levels of this enzyme. These results suggest that a change in hepatic cholesterol metabolism induced by continuous administration of pravastatin maintains a constant net balance of hepatic cholesterol content. In addition, the drug has no deleterious influence on metabolism of bile lipids and acids and related enzymes, except for a transient increase in cholesterol saturation in bile induced by an inappropriate increase in hepatic cholesterol content and a lack of response of cholesterol 7 alpha-hydroxylase activity to changes in hepatic cholesterol content upon abrupt withdrawal of pravastatin.

Fluorogenic reactions for biomedical chromatography

A number of fluorogenic reactions, which have been used for HPLC detection systems by means of pre- and/or postcolumn derivatization, are surveyed with respect to both sensitivity and selectivity for the determination of biomedically important substances. For the derivatization of the substances, two types of fluorogenic reactions, fluorescence-generating and fluorescence-tagging, have been studied. The former are usable in most instances for both pre- and postcolumn derivatization methods, and the latter only for precolumn derivatization methods. HPLC methods utilizing the fluorogenic reactions allow analytes to be detected at picomole-subfemtomole levels. In the fluorescence-generating reactions, several fluorogenic reagents possessing two or more reactive sites in the molecule, which show molecular recognition for a variety of analytes, permit facile and reproducible detection in HPLC because there are fewer interferences from biological matrices.

A practical reagent for reversible amino-protection of insulin, 3,4,5,6-tetrahydrophthalic anhydride

Of the examined dicarboxylic acid anhydrides, 3,4,5,6-tetrahydrophthalic anhydride was found to be the best reagent in practical use for reversible amino-protection of insulin in terms of the rapidity of acid-deprotection. Twelve Gly(A1),Phe(B1),Lys(B29)-triacyl-insulins were prepared by reaction of porcine insulin with the dicarboxylic acid anhydrides and time courses for the deprotection of the acylated insulins with dilute acetic acid were investigated by means of capillary zone electrophoresis, and the tetrahydrophthalyl(THP)-insulin obtained with the reagent was the most rapidly deacylated (6 h, 25 degrees C, 0.1 M acetic acid). Isolation of triacyl-insulins and Gly(A1)-THP-, Gly(A1),Phe(B1)-diTHP- and Gly(A1),Lys(B29)-diTHP-insulins using DEAE anion-exchange high-performance liquid chromatography is also described.

Preparative and analytical separations by high-performance liquid chromatography and capillary electrophoresis of the products from the reaction of insulin with exo-3,6-epoxy-1,2,3,6-tetrahydrophthalic anhydride

An anion-exchange high-performance liquid chromatographic method using a TSKgel DEAE-2SW column and zone electrophoresis using a fused-silica capillary are described for the preparative and analytical separations of the products of the reaction between insulin and exo-3,6- epoxy-1,2,3,6-tetrahydrophthalic anhydride (ETPA), an amino protective reagent. Four stable products were identified having exo-3,6-epoxy-1,2,3,6-tetrahydrophthalic group(s) on insulin at the i) Gly(A1), ii) Gly(A1) and Phe(B1), iii) Gly(A1) and Lys(B29), and iv) Gly(A1), Phe(B1) and Lys(B29) sites, together with four labile products produced by the reaction of ETPA with the non-amino groups of the stable products. The usefulness of capillary electrophoresis was demonstrated in the evaluation of the effect of the molar ratios of anhydride to insulin on the production of the insulin derivatives.

Determination of guanine and its nucleosides and nucleotides in human erythrocytes by high-performance liquid chromatography with postcolumn fluorescence derivatization using phenylglyoxal reagent

A high-performance liquid chromatographic method with on-line postcolumn fluorescence derivatization is described for the simple and sensitive determination of guanine and its nucleosides and nucleotides in human erythrocytes. After deproteinization of the biospecimen, guanine and its nucleosides and nucleotides were separated on a reversed-phase column (TSKgel ODS-120T) by gradient elution with methanol in the aqueous mobile phase consisting of tetra-n-propylammonium phosphate (pH 6.0) and phosphate buffer (pH 6.0). The compounds were then automatically converted into fluorescent derivatives by reaction with phenylglyoxal. This derivatization was selective for guanine-containing compounds. The present method permitted the reliable quantification of GDP and GTP in human erythrocytes. The detection limits (at a signal-to-noise ratio of 3) for guanine and its nucleosides and nucleotides were 3.2-10.0 pmol in a 20-microliters injection volume. The concentrations of GDP and GTP in human erythrocytes were 17.2 +/- 6.2 and 40.2 +/- 5.8 nmol/ml, respectively.

Identification of a functional receptor differing from the LDL receptor that catabolizes chylomicron remnant in Hep G2 cells

We investigated types of lipoprotein receptors on Hep G2 cells using a monoclonal antibody against the LDL receptor. IgG-C7 inhibited the binding and internalization of 125I-labeled low density lipoprotein (LDL) in Hep G2 cells with upregulated and downregulated LDL receptors by 90% of control values. Binding and internalization of 125I-labeled chylomicron remnant in Hep G2 cells with upregulated and downregulated LDL receptors was 50% and 85%, respectively, of control values after exposure to IgG-C7. Excess unlabeled chylomicron remnant inhibited binding and internalization of 125I-labeled chylomicron remnant in Hep G2 cells with downregulated LDL receptors completely. Pronase treatment abolished binding and internalization of 125I-labeled LDL and 125I-labeled chylomicron remnant in Hep G2 cells. When solubilized fractions of Hep G2 cells were immunoprecipitated with IgG-C7, the binding activity of 125I-labeled chylomicron remnant to reconstituted vesicles was unchanged. 45Ca blotting analysis showed the presence of 45Ca binding protein (approximately 600 kDa) in Hep G2 cells. The amount of 45Ca binding protein was not affected by cholesterol and was abolished by pronase treatment. These results suggest the existence of a functional receptor other than the LDL receptor that catabolizes chylomicron remnant in Hep G2 cells and that this receptor may correspond to LDL receptor-related protein.

Determination of a cysteine protease inhibitor and its ethyl ester in mouse serum and muscle by liquid chromatography-mass spectrometry

A liquid chromatographic-mass spectrometric method is described for the determination of a cysteine protease inhibitor (E64C) and its ethyl ester in mouse serum and muscle samples. The compounds in the sample, after deproteinization and solid-phase extraction, were separated by isocratic reversed-phase high-performance liquid chromatography and detected by on-line mass spectrometry. The use of an aqueous mobile phase containing methanol and 30 mM ammonium trichloroacetate provided abundant protonated molecular ions of the compounds in the atmospheric pressure chemical ionization interface of the detection system. The method permitted the quantitative determination of the inhibitors without internal standards in the biological matrices. The detection limits for the compounds, in the selected-ion monitoring mode, were 10-15 pmol on-column, at a signal-to-noise ratio of 5.

High-performance liquid chromatography of N-terminal tryptophan-containing peptides with precolumn fluorescence derivatization with glyoxal

A precolumn fluorescence derivatization method combined with high-performance liquid chromatography is described for the sensitive and selective determination of N-terminal tryptophan-containing peptides. The peptides and tryptophan were converted into fluorescent derivatives with glyoxal in a moderately acidic medium (pH 4.5). The derivatives were separated on a reversed-phase column with isocratic elution with an aqueous mobile phase composed of acetonitrile, methanol and phosphate buffer (pH 6.0), and subsequently detected by fluorimetry. The derivatization technique provided the respective N-terminal tryptophan-containing oligopeptides with single fluorescent peaks in chromatography. The detection limits for the peptides were 55-382 fmol per 100-microliters injection volume at a signal-to-noise ratio of 3. The method also allowed the facile detection of an N-terminal tryptophyl fragment in the enzyme reaction mixture of dynorphin A with trypsin.

Effect of spacer groups connecting insulin with fluorophore in Gly(A1)-sulfobenzoxadiazole-labeled insulins on the immunoreactivity toward anti-insulin antibody

The immunoreactivity (specific binding) of three Gly(A1)-sulfobenzoxadiazole-labeled insulins which have different spacer groups, Gly(A1)-[3-(4-sulfobenzoxadiazol-7-ylthio)propanoyl]-insulin , Gly(A1)-[2-(4-sulfobenzoxadiazol-7-ylthio)acetyl]-insulin, Gly(A1)-[3-carboxy-2(or 3)-(4-sulfobenzoxadiazol-7-ylthio)propanoyl]-insulin, toward an antiporcine insulin monoclonal antibody was investigated, where solid-phase fluoroimmunoassay technique was utilized. The immunoreactivities of three labeled insulins were 2.1, 1.8 and 1 in that order.

Effect of fluvastatin sodium (XU62-320), a new inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, on the induction of low-density lipoprotein receptor in HepG2 cells

The effect of fluvastatin sodium (XU62-320), a new type of inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A, on the induction of LDL receptor in the human liver-derived cell line HepG2 was investigated. Fluvastatin sodium produced marked inhibition of 3-hydroxy-3-methylglutaryl coenzyme A reductase activity and induction of LDL receptor on HepG2 cells at a concentration of 0.1-1.0 microM. These results suggest that fluvastatin sodium has potential for use as a strong plasma cholesterol-lowering drug.

Preparation and evaluation of fatty acid esters of 2-(4-hydroxyphenyl)-4,5-diphenylimidazole as fluorescent substrates for measurement of lipase activity

A series of four aliphatic carboxylic acid esters (acetate, caproate, laurate and palmitate) of 2-(4-hydroxyphenyl)-4,5-diphenylimidazole (HDPI) was prepared. Usefulness of these esters as fluorescent substrates for the measurement of lipase activity was evaluated using a high performance liquid chromatographic method. The hydrolysate, HDPI, could be well separated from each substrate by a reversed-phase column and detected at 440 nm emission (cutoff-filter) with 360 nm excitation. Lipase from Candida cylindracea was used for the investigation. From their kinetic parameters, the caproate and laurate were found to be suitable for the lipase. Using the laurate, from 5 to 500 mU per assay tube of the lipase was determined.

Amino acid transport system of the guinea pig small intestine is injured by hydroxyl radicals

The mechanism for the damage to the alanine-preferring amino acid transport system (A system) of guinea pig intestinal brush border membrane vesicles induced by active oxygen species was studied in vitro. The transport activity of L-proline, which is a model amino acid for the A system, and the tryptophan fluorescence intensity of intestinal brush border membrane vesicles were decreased, and lipid peroxidation of these membrane vesicles was induced by ultraviolet irradiation, which generated active oxygen species. Thiourea (hydroxyl radical scavenger) protected L-proline transport activity and tryptophan fluorescence intensity of intestinal brush border membrane vesicles and also inhibited lipid peroxidation in these membrane vesicles in the presence of active oxygen radicals. alpha-Tocopherol (singlet oxygen radical scavenger) inhibited lipid peroxidation of intestinal brush border membrane vesicles but protected neither L-proline transport activity nor tryptophan fluorescence intensity in these membrane vesicles in the presence of active oxygen radicals. Catalase and superoxide dismutase showed no protective effect on L-proline transport activity, tryptophan fluorescence intensity, or lipid peroxide formation in intestinal brush border membrane vesicles in the presence of active oxygen radicals.(ABSTRACT TRUNCATED AT 250 WORDS)

Partial cloning of cDNA for hamster liver cholesterol 7 alpha-hydroxylase

A partial cDNA clone encoding cholesterol 7 alpha-hydroxylase (pHA 7 alpha-3) was isolated from a hamster liver cDNA library using rat P-450 ch7 cDNA (p 7 alpha-11) as a probe. In comparison with the complete base sequence of p 7 alpha-11, pHA 7 alpha-3 lacked about 500 base pairs at the 5' end. Circadian rhythms of mRNA for hamster liver 3-hydroxy-3-methylglutaryl coenzyme A reductase and cholesterol 7 alpha-hydroxylase were investigated with cDNA clones encoding 3-hydroxy-3-methylglutaryl coenzyme A reductase (pRed-227) and pHA 7 alpha-3. Typical circadian rhythms of mRNA for both enzymes and a time lag between the two circadian rhythms were observed. The circadian rhythm of activity for each enzyme corresponded to that of each mRNA.

Determination of tryptophan in human serum by high-performance liquid chromatography with pre-column fluorescence derivatization using phenylglyoxal

A high-performance liquid chromatographic method based on pre-column fluorescence derivatization with phenylglyoxal is described for the sensitive and selective quantification of total (free plus albumin-bound) and free tryptophan in serum. Serum was deproteinized with perchloric acid for total tryptophan and by ultrafiltration for free tryptophan, and then subjected to fluorescence derivatization. The reaction mixture was separated on a reversed-phase column by isocratic elution and the tryptophan derivative was then detected by fluorimetry. The method was at least ten-fold more sensitive than other conventional chromatographic methods with no derivatization. The lower limit of determination (signal-to-noise ratio = 3) for endogenous tryptophan in human serum was 72 nmol/l, which corresponds to 200 fmol on-column.

Effect of dietary hydrogenated corn oil (trans-octadecenoate rich oil) on plasma and hepatic cholesterol metabolism in the hamster

The effect of dietary hydrogenated corn oil (trans-octadecenoate-rich oil) on plasma cholesterol and triglyceride concentrations was compared with dietary palmitic acid in hamsters given a cholesterol-rich diet. The addition of dietary palmitic acid and hydrogenated corn oil accelerated the increase in plasma VLDL- and LDL-cholesterol levels and plasma triglyceride level induced by dietary cholesterol loading. Dietary cholesterol, palmitic acid and hydrogenated corn oil showed no effect on plasma HDL-cholesterol concentration. A decrease in hepatic LDL receptor activity was seen in animals fed a diet supplemented with cholesterol in combination with palmitic acid or hydrogenated corn oil in comparison with animals fed a diet supplemented with cholesterol alone. Hydrogenated corn oil (trans-octadecenoate-rich oil) appears to potentiate the effect of dietary cholesterol in elevating the plasma VLDL- and LDL-cholesterol levels through the suppression of hepatic LDL receptor activity. trans-Octadecenoate in dietary hydrogenated corn oil may be as atherogenic as dietary palmitic acid due to a suppression of hepatic LDL receptors in the presence of dietary cholesterol loading.

Preparation of fluorescence labeled insulins, sulfobenzoxadiazolyl-insulins, for fluorescence immunoassay

The preparation of insulins labeled with a fluorescent moiety at a definite position (Gly(A1) or Lys(B29)) on the molecule is described. Gly(A1)- and Lys(B29)-S-acetylthioglycoloyl-insulins and Gly(A1)-2(or 3)-acetylmercapto-3-carboxypropranoyl-insulin were deacetylated and then reacted with 7-chloro-4-sulfobenzoxadiazole, a fluorogenic reagent, to afford the corresponding fluorescence labeled insulins. The preparative separation of the fluorescence labeled insulins from the insulin derivatives that remained unreacted was carried out by anion-exchange high-performance liquid chromatography on a TSKgel DEAE-2SW column.

Increase in lipoprotein lipase activity in isolated rat adipose tissue by selenate

Sodium selenate (selenate), as well as insulin, increased the lipoprotein lipase (LPL) activity in isolated rat fat pads in a time- and dose-dependent manner. The increase effect of selenate was not additive to that of insulin. The action of selenate and insulin was decreased by amiloride and disappeared when Ca2+ was omitted from the incubation medium. Loading of a chelator of intracellular Ca2+ to the fat pads also greatly inhibited the action of selenate. The maximal increase in inositol 1,4,5-trisphosphate (IP3) content was observed with a 30-s incubation of the fat pads with selenate. Dibutyryl cyclic AMP, 3-isobutyl-1-methylxanthine, carbonyl cyanide m-chlorophenylhydrazone, tunicamycin, and monensin all inhibited the increase effect of selenate on the LPL activity to various extents. These results suggest that selenate increases the LPL activity via amiloride- and monensin-sensitive processes, involving the Ca2+ mobilization linked to a rapid increase in the IP3 content in fat pads.

A fluorescent DNA probe prepared by the direct derivatization of the sugar moiety for hybridization assay

The preparation of a fluorescent DNA probe based on the derivatization of the terminal hydroxyl group of the sugar moiety of a DNA primer and its applicability to the DNA hybridization assay are described. M13mp8 plasmid primer reacts with 2-(5-chlorocarbonyl-2-oxazolyl)-5,6-methylenedioxybenzofu ran in the presence of sodium azide to form the corresponding fluorescent probe, which can be used for the hybridization assay to the target DNA, M13mp8 plasmid vector. The detection limit of the DNA with the naked eye is 10 ng (approximately 300 fmol)/spot on filters for the hybridization assay.

Precolumn derivatization of nucleotides based on fluorescent carbamate formation of the sugar moieties in high-performance liquid chromatography

The fluorescence derivatization of nucleotides with 2-(5-chlorocarbonyl-2-oxazolyl)-5,6-methylenedioxybenzo++ furan in the presence of sodium azide and the separation of the derivatives by high-performance liquid chromatography are described. The reagent reacts with 5'-terminal hydroxyl groups of nucleotides to produce the corresponding fluorescent carbamates. The derivatives of mono- and oligonucleotides are separated by chromatography on a reversed phase column (TSKgel ODS-80TM) and the derivatives of octa- and deca-nucleotides on a size exclusion column (TSKgel G3000SWXL). The detection limits (signal-to-noise ratio = 3) are 0.8-6.0 pmol on column. 5'Phosphorylated nucleotide also gives a fluorescent derivative after alkaline phosphatase-mediated dephosphorylation.

Removal of endotoxin from culture supernatant of Bordetella pertussis with aminated poly(gamma-methyl L-glutamate) spherical beads

Attempts were made to prepare adsorbents having a high affinity for endotoxin in the culture supernatant of Bordetella pertussis. When poly(gamma-methyl L-glutamate) (PMLG) was used as a matrix and amino groups as the ligand, the highest affinity for endotoxin was attained even at a high ionic strength (mu = 0.2-0.4). PMLG beads containing amino groups of about 3.2 meq/g selectively removed endotoxin from the culture supernatant of B. pertussis without affecting the protective antigens. It was demonstrated that 1 ml of the wet adsorbent adsorbed 4.5 mg of endotoxin. The beads of PMLG derivatives, therefore, are considered to be a useful adsorbent for the removal of endotoxin from the pertussis vaccine, affecting neither filamentous hemagglutinin nor pertussis toxin.

Determination of 2',3'-dideoxyinosine and 2',3'-dideoxyadenosine in rat plasma by high-performance liquid chromatography with precolumn fluorescence derivatization

A high-performance liquid chromatographic method with precolumn fluorescence derivatization using 2-(5-chlorocarbonyl-2-oxazolyl)-5,6-methylenedioxybenzofu ran is described for the quantification of 2',3'-dideoxyinosine, a therapeutic drug for acquired immunodeficiency syndrome, and 2',3'-dideoxyadenosine, an anti-human-immunodeficiency-viral agent, in rat plasma. The dideoxyribonucleosides and 3'-deoxythymidine (internal standard) in rat plasma (0.1 ml) are cleaned up by a solid-phase extraction technique using an octadecyl silica (ODS) cartridge, Toyopak ODS M, and the dideoxyribonucleosides in the eluate are reacted with the reagent to produce the corresponding fluorescent esters. The esters are separated by chromatography on a reversed phase column, TSKgel ODS-80TM. The detection limits (signal-to-noise ratio = 3) for the dideoxyribonucleosides are 1.3-5.4 pmol on column. Plasma concentrations of 2',3'-dideoxyinosine after intra-jugular-venous administration to rat can be monitored by this method.

Preparation of acetylmercapto-3-carboxypropanoyl insulins using preparative high-performance liquid chromatography on an anion-exchange column

A method for the preparation of insulin derivatives which have protected sulfhydryl group(s) at definite site(s) on the molecule is described. Porcine insulin reacts with S-acetylmercaptosuccinic anhydride to afford four species of insulin derivatives that have 2 (or 3)-acetylmercapto-3-carboxypropanoyl group(s) at i) Gly(A1), ii) Gly(A1) and Phe(B1), iii) Gly(A1) and Lys(B29), and iv) Gly(A1), Phe(B1) and Lys(B29) positions. The derivatives are efficiently separated in a preparative scale by anion-exchange high-performance liquid chromatography on a TSKgel DEAE-2SW column. The four derivatives are all readily deacetylated with hydroxylamine to give the corresponding sulfhydryl insulin derivatives.