Effects of high-fat diet and exercise training on intracellular glucose metabolism in rats

We examined the effects of high-fat diet (HFD) and exercise training on insulin-stimulated whole body glucose fluxes and several key steps of glucose metabolism in skeletal muscle. Rats were maintained for 3 wk on either low-fat (LFD) or high-fat diet with or without exercise training (swimming for 3 h per day). After the 3-wk diet/exercise treatments, animals underwent hyperinsulinemic euglycemic clamp experiments for measurements of insulin-stimulated whole body glucose fluxes. In addition, muscle samples were taken at the end of the clamps for measurements of glucose 6-phosphate (G-6-P) and GLUT-4 protein contents, hexokinase, and glycogen synthase (GS) activities. Insulin-stimulated glucose uptake was decreased by HFD and increased by exercise training (P < 0.01 for both). The opposite effects of HFD and exercise training on insulin-stimulated glucose uptake were associated with similar increases in muscle G-6-P levels (P < 0.05 for both). However, the increase in G-6-P level was accompanied by decreased GS activity without changes in GLUT-4 protein content and hexokinase activities in the HFD group. In contrast, the increase in G-6-P level in the exercise-trained group was accompanied by increased GLUT-4 protein content and hexokinase II (cytosolic) and GS activities. These results suggest that HFD and exercise training affect insulin sensitivity by acting predominantly on different steps of intracellular glucose metabolism. High-fat feeding appears to induce insulin resistance by affecting predominantly steps distal to G-6-P (e.g., glycolysis and glycogen synthesis). Exercise training affected multiple steps of glucose metabolism both proximal and distal to G-6-P. However, increased muscle G-6-P levels in the face of increased glucose metabolic fluxes suggest that the effect of exercise training is quantitatively more prominent on the steps proximal to G-6-P (i.e., glucose transport and phosphorylation).

No association between alpha-1-antichymotrypsin polymorphism and Alzheimer's disease in Koreans

To examine the possible involvement of the alpha-1-antichymotrypsin gene (ACT) polymorphism in the manifestation of Alzheimer's disease (AD), we analyzed genotypes of the ACT and apolipoprotein E gene (APOE) among 110 Korean patients with probable AD and 209 nondemented controls. No significant difference was obtained in genotypic (chi(2)=1.98, df=2, P>0.1) and allelic frequencies (chi(2)=1.61, df=1, P>0.1) of ACT between the AD and control groups. No overexpression of the ACT A/A genotype and ACT A allele was found when we analyzed the late-onset AD patients and the early-onset AD patients, separately. Then we stratified the ACT genotypes based on the presence or absence of the APOE epsilon4 allele to evaluate the possible interaction between them. In the APOE epsilon4-negative subjects, although the ACT A allele tended to be overexpressed in the AD group, the differences in the frequencies of the ACT A allele (chi(2)=2.79, df=1, P>0.1) and ACT A/A genotype (chi(2)=0.16, df=1, P>0.1) were not statistically significant. No significant overrepresentations of the ACT A allele (chi(2)=0.02, df=1, P>0.1) and ACT A/A genotype (chi(2)=0.17, df=1, P>0.1) were found in the APOE epsilon4-positive subjects, either. In addition, the status of the ACT genotype did not influence the age-at-onset of AD (F=0.03, df=2, P>0.1). Therefore, the ACT polymorphism does not contribute to the development of AD independently or interactively with the APOE epsilon4 allele in Koreans.

A telemedicine system as a care modality for dementia patients in Korea

Because dementia is a chronic debilitating disease, there are the issues of the difficulty in continuous long-term care and limited accessibility to medical service. We developed the telemedicine system for dementia patients and aimed to examine the acceptance, reliability, and clinical outcome of our telemedicine service. We established the Dementia Telemedicine Center in connection with two recipient sites in 1996. The reliability of the center, which provides telemedicine, tele-education, and telecounseling services, was tested by comparing assessment via our system with in-person assessment, and the clinical outcome was assessed by rating the changes of behavioral symptoms. There have been 140 registered patients for 2 years. The general acceptance of our system by the patients and caregivers was good, and the consistency rates between the assessment via our telemedicine system and in-person assessment ranged from 76% to 89%. A considerable proportion of dementia patients in nursing homes (46%) showed relative clinical improvements through our service. Our telemedicine system seems to be reliable and effective for the assessment and care of dementia patients. Our future direction is to promote our system as a core model of the home-based care system for dementia patients.

Increased urinary albumin excretion in Cushing's syndrome: remission after correction of hypercortisolaemia

OBJECTIVES

Increased urinary albumin excretion (UAE) in diabetic and nondiabetic subjects is frequently associated with insulin resistance syndrome and central obesity. Cushing's syndrome is also characterized by central obesity and insulin resistance. This study was undertaken to see whether increased UAE is found in Cushing's syndrome.

DESIGN

Cross-sectional study.

PATIENTS

Thirteen consecutive patients with Cushing's syndrome.

MEASUREMENTS

Patients collected three overnight urine samples for the measurement of UAE by radioimmunoassay. UAE was also measured in 479 nondiabetic subjects who comprised the control population for this study. In the patients who had initial microalbuminuria, UAE was remeasured 2 months after successful removal of pituitary or adrenal tumours. Kidney biopsy was performed in three patients during adrenalectomy.

RESULTS

Eleven out of 13 patients (84.6%) had increased UAE (> 9.6 micrograms/min), and eight patients (61.5%) had microalbuminuria or overt proteinuria (> 20 micrograms/min). Kidney biopsy revealed apparently normal glomerular structures without evidence of diabetic nephropathy. After correction of hypercortisolaemia, UAE declined profoundly in all of the patients.

CONCLUSIONS

More than 80% of patients with Cushing's syndrome had increased UAE. This was almost completely reversed after successful treatment of hypercortisolaemia. These results indicate that endogenous hypercortisolaemia increases UAE by a mechanism that is presently unknown.

Clinicopathologic features of the intraductal growth type of peripheral cholangiocarcinoma

The clinicopathologic features of the intraductal growth (IG) type of peripheral cholangiocarcinoma (PCC) were examined retrospectively. Out of 112 patients who underwent surgery for PCC at Seoul National University Hospital, Seoul, Korea, between January 1980 and December 1997, 16 were classified as having the IG type. Thirteen were men and 3 were women. Their ages ranged from 38 to 73 years with a mean age of 55.9 years. Abdominal pain was the most common symptom and jaundice was found in 18.8%. Five patients had associated clonorchiasis and 6 patients experienced hepatolithiasis. Tumor sizes ranged from 0.5 cm to 14.0 cm with a mean of 4.3 cm. The tumor was located in the right lobe in 7 cases and the left lobe in 9 cases. Thirteen patients underwent major hepatic resection, and 3 underwent minor resection, involving a subsegmentectomy. Mucin was found in the bile in 4 cases. Pathology showed papillary adenocarcinoma with a background of adenomatous hyperplasia, and the absence of lymph node metastasis in all cases. The tumors were confined to the mucosa in 5 cases. Out of the 16 hepatic resections, 1 was palliative due to a positive margin. In 2 of the patients who underwent minor resections, recurrences developed, and 1 of these died 56 months after resection. Out of the 16 patients, 15 remain alive, ranging from 1 to 13 years, postoperatively. In conclusion, the IG type of PCC should be distinguished from other types of PCC because a favorable prognosis can be expected after complete surgical resection.

Suppression of endogenous insulin secretion by exogenous insulin in patients with insulinoma

OBJECTIVE

Previous studies have demonstrated that endogenous insulin secretion is not suppressed by exogenous insulin in patients with insulinoma. In this study we examined whether insulin secretion in insulinoma patients is suppressed by exogenous insulin during hypoglycaemia.

SUBJECTS AND METHODS

Sixteen insulinoma patients (5 men and 11 women) and 10 normal subjects were studied. Hyperinsulinaemic glucose clamp studies were performed at both euglycaemia (4.5 mmol/l glucose) and hypoglycaemia (2.5 mmol/l glucose).

RESULTS

In normal subjects, plasma C-peptide levels were suppressed by 66% during the euglycaemic hyperinsulinaemic clamps (P < 0.01). In contrast, in insulinoma patients, plasma C-peptide levels increased by 25% during the clamps (P < 0.05). In the hypoglycaemic hyperinsulinaemic clamps, plasma C-peptide levels were nearly completely (91%) suppressed in normal subjects and partially (39%) suppressed in patients with insulinoma (P < 0.01). The decrease in C-peptide levels during the hypoglycaemic clamps was > 30% in 12 (75%) of 16 insulinoma patients and > 50% in 8 (50%) patients.

CONCLUSIONS

This study demonstrated that in patients with insulinoma, insulin secretion was not suppressed by exogenous insulin during euglycaemia but was suppressed during hypoglycaemia, although the degree of suppression was less than that in normal subjects. Our results suggest that the feedback regulation of insulin secretion by exogenous insulin is partially retained in patients with insulinoma.

Association between apolipoprotein E polymorphism and Alzheimer's disease in Koreans

We analyzed the aplolipoprotein E (APOE) genotypes of 110 probable AD patients and 226 cognitively normal controls in Koreans. The APOE epsilon4 allele was more prevalent in both early- and late-onset AD patients (P < 0.01) than in controls. The odds for the APOE epsilon4-heterozygous subjects were 2.7 (95% CI = 1.6-4.5), and those for the APOE epsilon4-homozygous subjects were 17.4 (95% CI = 2.0-147.3). But the odds were not uniform across age groups, and were higher in women than in men. Although the APOE epsilon2 allele frequency did not differ by diagnosis, the patients carrying an APOE epsilon2 allele showed delayed age-at-onset (P = 0.02). In conclusion, the APOE e4 allele increased the risk for AD in dose-dependent manner, and the APOE epsilon4-conferred AD risk was age- and sex-dependent in Koreans.

Peripheral blood mitochondrial DNA content correlates with lipid oxidation rate during euglycemic clamps in healthy young men

Both qualitative and quantitative changes in mitochondrial DNA (mtDNA) have been implicated in the pathogenesis of diabetes mellitus. It was previously found that decreased mtDNA content preceded the development of diabetes and mtDNA content correlated with the clinical parameters of insulin resistance syndrome, including diastolic blood pressure and waist-hip ratio. These results prompted one to look whether there are correlations between mtDNA content and the biochemical parameters of insulin resistance in non-diabetic subjects. MtDNA content of peripheral blood leukocytes was measured in Korean healthy young men, and this was correlated with various parameters of fuel metabolism at baseline and during euglycemic hyperinsulinemic clamps with indirect calorimetry. MtDNA content in peripheral blood leukocytes did not correlate with insulin sensitivity index or other metabolic variables such as body mass index (BMI), waist-to-hip ratio (WHR) and blood pressure. However, mtDNA content showed a positive significant correlation with fat oxidation rate during euglycemic clamps (r = 0.61, P < 0.05). Changes in fat oxidation rate and carbohydrate oxidation rate during the clamps were significantly correlated with mtDNA content (r = 0.65, P < 0.05, r = -0.65, P < 0.05, respectively). These results suggest that mtDNA content in peripheral blood may not correlate with insulin resistance per se but with some aspect of insulin resistance in healthy young men.

Prognostic factors in 2230 Korean colorectal cancer patients: analysis of consecutively operated cases

To define the prognostic factors in Korean colorectal cancer patients, univariate and multivariate analysis were performed on data from 2230 consecutive patients who underwent resection for colorectal cancer at the Seoul National University Hospital. The prognostic variables used for the analysis included patient's age, gender, bowel obstruction, bleeding, symptom duration, preoperative leukocyte count, preoperative serum carcinoembryonic antigen (CEA) level, Dukes' stage, tumor location, tumor size, depth of bowel wall invasion, number of lymph node metastases, histologic differentiation, and gross morphology of tumor. The overall 5-year survival rate was 62%. In the univariate analysis, all the factors except sex, symptom duration, and tumor size were associated with prognosis. Among the factors significant in the univariate analysis, Dukes' stage (p < 0.001), number of lymph node metastasis (p < 0.001), CEA level (p < 0.001), tumor location (p = 0.003), gross morphology of tumor (p = 0.017), and depth of bowel wall invasion (p = 0.031) were significant in the multivariate analysis. Several differences in prognostic factors between colon cancer and rectal cancer were observed. In the multivariate analysis, gross tumor morphology was significant only for colon cancer, and histologic differentiation was significant only for rectal cancer. Lymph node metastasis was an independent prognostic variable for both colon and rectal cancer, but its significance was more prominent for rectal cancer. Although Dukes' stage is the most reliable prognostic predictor, this study shows that other factors (preoperative CEA level, gross morphology of tumor, location of tumor, nodal status) also provide important information for the outcome of the patient.

Pharmacokinetic-pharmacodynamic modeling of risperidone effects on electroencephalography in healthy volunteers

RATIONALE

CNS-active drugs produce specific electroencephalographic changes and the concentration-effect relationship of antipsychotics may be elucidated by adopting electroencephalography (EEG) as an effect measurement tool.

OBJECTIVE

The purpose of the present study was to determine the concentration-effect relationship of risperidone by assessing the EEG effect after oral administrations of single dose risperidone in healthy young males.

METHODS

Nine healthy male volunteers received a 1 mg single oral dose of risperidone according to a placebo controlled crossover design. Plasma levels of risperidone and its active metabolite 9-hydroxyrisperidone were measured by radioimmunoassay. Quantitative EEG parameters were obtained for each of four frequency bands through spectral EEG analysis. The difference in the absolute power in the delta frequency band for the F3 lead between risperidone and placebo was used as a drug effect parameter. For pharmacokinetic-pharmacodynamic modeling, the hypothetical effect compartment kinetically linked to plasma by a first-order process was postulated. All curve fittings were done with the non-linear curve-fitting program NONLIN.

RESULTS

Our results showed that absolute powers in delta and theta frequency bands were higher for risperidone administration than for placebo at all EEG leads, and the maximum effects were detected at about 3 h after administration of the drug. The hysteresis loop was observed in the plot of plasma concentration of risperidone or sum of risperidone and 9-hydroxyrisperidone (Cp) versus EEG effect for each subject. A linear model adequately described the relationship between the effect compartment concentrations (Ce) and EEG effects, and the two limbs of hysteresis in the Cp-effect plot were collapsed in the Ce-effect plot for risperidone or risperidone plus 9-hydroxyrisperidone.

CONCLUSION

The increases of absolute power for delta and theta frequency bands of EEG were induced by single oral administration of risperidone. The linear PK-PD model fit well with the relationship between effect compartment concentrations (Ce) and EEG effects of risperidone.

Experience of 1446 rectal cancer patients in Korea and analysis of prognostic factors

In order to investigate the changing pattern of rectal cancers in Korea and to identify prognostic factors, we investigated the case histories of 1446 rectal cancer patients who had received surgical treatment. During the study period there were trends toward a decrease in the ratio of rectal cancer to colon cancer, earlier detection (more Dukes' stages A and B and fewer C), a decrease in the number of abdominoperineal resections, and an increase in the number of sphincter-preserving operations. Univariate analysis of prognostic factors showed that gender, obstruction symptoms, preoperative serum carcinoembryonic antigen (CEA) level, tumor size, depth of bowel wall invasion, lymph node metastases (presence and number), tumor differentiation, operative method, and date of operation were significant, but age, symptom duration, and tumor location were not. The use of sphincter-saving operations did not adversely affect the clinical outcome. Multivariate analysis showed lymph node metastasis factor to be the most significant factor (P < 0.001); the depth of bowel wall invasion, differentiation, CEA level, and date of operation were also significant (0.001 < P < 0.05). This study shows that although anatomical extent of disease (depth of invasion and lymph node metastasis) is the most reliable prognostic predictor in rectal cancer, other factors such as preoperative CEA level and tumor differentiation also provide important information on the outcome and use of an anal-preserving operation does not adversely affect the patient survival.

Elevated plasma proinsulin/insulin ratio is a marker of reduced insulin secretory capacity in healthy young men

AIM

To examine whether reduced insulin secretory capacity or increased insulin secretory demand is associated with elevated ratio of plasma proinsulin to immunoreactive insulin (PI/IRI ratio) in non-diabetic subjects.

SUBJECTS AND METHODS

We measured various indices of insulin secretory function and insulin sensitivity by frequently sampled intravenous glucose tolerance test (FSIGT) and hyerglycemic glucose clamp in 21 healthy young men. We then examined the relationships between these indices and PI, IRI, or PI/IRI ratio in the fasting state.

RESULTS

Insulin sensitivity index (SI) measured by FSIGT correlated inversely with basal IRI (r=-0.53, P < 0.01) and PI levels (r=-0.57, P < 0.01), but there was no significant correlation between SI and PI/IRI ratio (r=0.26, NS). On the other hand, PI/IRI ratio correlated inversely with insulin secretory indices, such as acute insulin responses during FSIGT (r =-0.46, P < 0.01) and hyperglycemic glucose clamp (r=-0.54, P < 0.01) and submaximum insulin response during hyperglycemic glucose clamp (r=-0.59, P < 0.01).

CONCLUSIONS

These results indicate that elevated PI/IRI ratio may serve as a marker of reduced insulin secretory function in non-diabetic subjects.

Thyroid hormone stimulates basal and interleukin (IL)-1-induced IL-6 production in human bone marrow stromal cells: a possible mediator of thyroid hormone-induced bone loss

It is well known that excessive thyroid hormone in the body is associated with bone loss. However, the mechanism by which thyroid hormone affects bone turnover remains unclear. It has been shown that it stimulates osteoclastic bone resorption indirectly via unknown mediators secreted by osteoblasts. To determine if interleukin-6 (IL-6) or interleukin-11 (IL-11) could be the mediator(s) of thyroid hormone-induced bone loss, we studied the effects of 3,5,3'-tri-iodothyronine (T3) on basal and interleukin-1 (IL-1)-stimulated IL-6/IL-11 production in primary cultured human bone marrow stromal cells. T3 at 10(-12)-10(-8) M concentration significantly increased basal IL-6 production in a dose-dependent manner. It also had an additive effect on IL-1-stimulated IL-6 production, but failed to elicit a detectable effect on basal or IL-1-stimulated IL-11 production. Treatment with 17beta-estradiol (10(-8) M) did not affect the action of T3 on IL-6/IL-11 production. These results suggest that thyroid hormone may stimulate bone resorption by increasing basal and IL-1-induced IL-6 production from osteoblast-lineage cells, and these effects are independent of estrogen status.

High serum lipoprotein(a) levels in Korean type 2 diabetic patients with proliferative diabetic retinopathy

OBJECTIVE

To examine the possible association between serum lipoprotein(a) [Lp(a)] concentration and proliferative diabetic retinopathy (PDR) in Korean patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

A total of 412 Korean outpatients with type 2 diabetes were examined. Diabetic retinopathy was determined by an ophthalmologist using fundoscopic examination. Serum Lp(a) levels were measured by two-site sandwich enzyme-linked immunosorbent assay.

RESULTS

The patients with PDR had higher serum Lp(a) levels than those with no diabetic retinopathy or with nonproliferative diabetic retinopathy (NPDR). Multiple logistic regression analysis showed that high serum Lp(a) levels and the presence of diabetic nephropathy were independent variables having a statistically significant association with PDR.

CONCLUSIONS

Korean type 2 diabetic patients with PDR had higher serum Lp(a) levels versus those with no diabetic retinopathy or with NPDR. Although these results suggest that Lp(a) might play a role in the occlusion of retinal capillaries leading to PDR, further prospective studies are required to prove the causal relationship.

Decreased mitochondrial DNA content in peripheral blood precedes the development of non-insulin-dependent diabetes mellitus

Qualitative changes in mitochondrial DNA (mtDNA), such as mutations and deletions, have been implicated in the pathogenesis of diabetes mellitus. In addition to the qualitative changes, mtDNA is subject to quantitative changes, and is vulnerable to oxidative stress, resulting in both qualitative and quantitative changes. This study was performed to investigate whether quantitative changes in mtDNA occur in non-insulin-dependent diabetes mellitus (NIDDM) patients and also in pre-diabetic subjects. MtDNA content from peripheral blood was measured by slot-blot analysis in 55 NIDDM patients and 29 age- and sex-matched control subjects. We have also analysed the mtDNA copies by quantitative polymerase chain reaction (PCR) method in 23 pre-diabetic subjects who converted to diabetic in 2 years and 22 age- and sex-matched control subjects who remained non-diabetic. Mean mtDNA quantity measured by slot blot method was 35% lower in patients with NIDDM than in control subjects (12.3+/-8.1 vs. 19.1+/-8.2 AU/microg DNA; P < 0.05). MtDNA quantities did not correlate with age, body mass index, duration of diabetes or HbA1c levels. We have also found that the mtDNA copies in subjects who converted to diabetes in 2 years were lower than in controls even before the development of diabetes (102.8+/-41.5 vs. 137.8+/-67.7 copies/pg template DNA P < 0.05). Inverse correlations were noted between mtDNA content and baseline waist hip circumference ratio (WHR) (r = -0.31, P < 0.05), and fasting glucose level (r = - 0.35, P < 0.05), diastolic blood pressure (r = -0.36, P < 0.05), and WHR (r = -0.40, P < 0.01) after development of diabetes. In conclusion, we demonstrate that the content of mtDNA decreases in peripheral blood of patients with NIDDM and the lower mtDNA levels precede the development of diabetes.

Effects of FFA on insulin-stimulated glucose fluxes and muscle glycogen synthase activity in rats

To examine effects of free fatty acids (FFA) on insulin-stimulated glucose fluxes, euglycemic hyperinsulinemic (86 pmol . kg-1 . min-1) clamps were performed for 5 h in conscious rats with (n = 8) or without (n = 8) lipid-heparin infusion. Glucose infusion rate required to maintain euglycemia was not different between the two groups during the first 2 h of clamps but became significantly lower with lipid-heparin infusion in the 3rd h and thereafter. To investigate changes in intracellular glucose metabolism during lipid-heparin infusion, additional clamps (n = 8 each) were performed for 1, 2, 3, or 5 h with an infusion of [3-3H]glucose. Insulin-stimulated whole body glucose utilization (Rd), glycolysis, and glycogen synthesis were estimated on the basis of tracer concentrations in plasma during the final 40 min of each clamp. Similar to changes in glucose infusion rate, Rd was not different between the two groups in the 1st and 2nd h but was significantly lower with lipid-heparin infusion in the 3rd h and thereafter. Whole body glycolysis was significantly lower with lipid-heparin infusion in all time periods, i.e., 1st, 2nd, 3rd, and 5th h of clamps. In contrast, whole body glycogen synthesis was higher with lipid-heparin infusion in the 1st and 2nd h but lower in the 5th h. Similarly, accumulation of [3H]glycogen radioactivity in muscle glycogen was significantly higher with lipid-heparin during the 1st and 2nd h but lower during the 3rd and 5th h. Glucose 6-phosphate (G-6-P) concentrations in gastrocnemius muscles were significantly higher with lipid-heparin infusion throughout the clamps. Muscle glycogen synthase (GS) activity was not altered with lipid-heparin infusion at 1, 2, and 3 h but was significantly lower at 5 h. Thus increased availability of FFA significantly reduced whole body glycolysis, but compensatory increase in skeletal muscle glycogen synthesis in association with accumulation of G-6-P masked this effect, and Rd was not affected in the early phase (within 2 h) of lipid-heparin infusion. Rd was reduced in the later phase (>2 h) of lipid-heparin infusion, when glycogen synthesis was reduced in association with reduced skeletal muscle GS activity.

Association of microalbuminuria and atherosclerotic risk factors in non-diabetic subjects in Korea

Microalbuminuria in non-diabetic subjects is reportedly associated with increased cardiovascular morbidity and mortality. The prevalence of microalbuminuria in non-diabetic subjects varies widely from 5-6% in the UK and USA to 30-55% in Finland, Mexico, or Australian Aborigines. We studied cross-sectionally 497 clinically healthy, non-diabetic subjects more than 40 years of age who were living in Seoul, Korea for the prevalence of microalbuminuria and various cardiovascular risk factors. Urinary albumin-to-creatinine ratio (UACR) was determined in morning spot urine samples. Subjects were divided into normoalbuminuria (UACR < 2 mg/mmol) and microalbuminuria (UACR > or = 2 mg/mmol) groups. A total of 61 (12.2%) out of 497 subjects were found to have microalbuminuria. Subjects with microalbuminuria had significantly higher values in age, body mass index (BMI), waist-to-hip ratio in women, systolic and diastolic blood pressure, prevalence of hypertension, plasma cholesterol and triglyceride, and fasting plasma insulin. When subjects with microalbuminuria were compared with age-, sex-, and BMI-matched controls without microalbuminuria, systolic and diastolic blood pressure, and fasting plasma insulin concentrations were higher in microalbuminuric subjects. Multiple logistic regression analysis showed that fasting plasma insulin level and systolic blood pressure were independently associated with microalbuminuria. These results indicate that the prevalence of microalbuminuria in Korean non-diabetic subjects is lower than that in Mexico and Finland, but similar to that in Caucasians from the UK and USA, or in Pima Indians. Also, microalbuminuria in Korean non-diabetic subjects is associated with atherosclerotic risk factors such as hyperinsulinemia and hypertension, suggesting that microalbuminuria in these subjects may be a feature of insulin resistance syndrome.

Primary ovarian failure caused by a solvent containing 2-bromopropane

Sixteen Korean female laborers who had been exposed to a cleaning solvent composed mainly of 2-bromopropane developed primary ovarian failure. Histologic findings from these patients' ovaries were similar to those observed in ovarian failure caused by radiation or chemotherapy, i.e., reduced number and developmental arrest of primary follicles, interstitial fibrosis and hyalinization of blood vessels. We followed their clinical course for 2 years and found that two patients recovered normal ovarian function spontaneously: one became pregnant and delivered a normal full-term baby, and the other resumed regular menstrual periods with normal hormonal values. Our observations support the idea that the increasing prevalence of ovarian failure in recent years might be due to an increase in presently unidentified environmental toxic agents.

Incidence and determinants of microalbuminuria in Koreans with type 2 diabetes

OBJECTIVE

The incidence of diabetic nephropathy in type 2 diabetes differs widely by race. Although clinical proteinuria is reportedly more common in East Asian type 2 diabetic patients than in their Caucasian counterparts, data on the incidence of microalbuminuria are not available. This study was undertaken to investigate the incidence and the determinants of microalbuminuria in Korean type 2 diabetic patients.

RESEARCH DESIGN AND METHODS

A cohort of 188 Korean type 2 diabetic patients with initial normoalbuminuria were followed prospectively for 5.5 +/- 0.9 years in an outpatient clinic of a university hospital. The incidence of elevated urinary albumin excretion (UAE) (> 20 micrograms/min) and its relationship with baseline characteristics and follow-up data were determined.

RESULTS

Of the 146 patients who finished the study, 37 showed persistently elevated UAE during follow-up, giving an incidence of 52/1,000 person-years. Age, duration of diabetes, and baseline UAE were significantly higher in the progressors than in the nonprogressors. More patients in the progressor group had retinopathy at baseline and at the end of follow-up. The mean values of fasting plasma glucose, HbA1, and systolic and diastolic blood pressure during the follow-up period were significantly higher in the progressors than in the nonprogressors. Cox proportional hazards analysis revealed that presence of retinopathy, duration of diabetes, mean fasting plasma glucose, and mean systolic blood pressure during follow-up are independent variables that have a statistically significant influence on the development of microalbuminuria.

CONCLUSIONS

The incidence of microalbuminuria in Korean type 2 diabetic patients is lower than that reported in Pima Indians with type 2 diabetes but is as high as that in Caucasians with type 1 diabetes. Presence of diabetic retinopathy, poor glycemic control, and high blood pressure are risk factors for development of microalbuminuria in Koreans with type 2 diabetes.

Development and progression of diabetic retinopathy in Koreans with NIDDM

OBJECTIVE

To determine the incidence and risk factors for the development and progression of diabetic retinopathy in Korean patients with NIDDM.

RESEARCH DESIGN AND METHODS

A total of 186 patients with NIDDM who did not have proliferative diabetic retinopathy (PDR) at baseline were prospectively studied for 5.3 +/- 1.0 years in an outpatient clinic of a university hospital. The incidence and progression of diabetic retinopathy was determined by annual funduscopic examination by an ophthalmologist.

RESULTS

Of the 130 patients who were free of diabetic retinopathy at baseline, 30 developed it, giving an incidence of 44.4/1,000 person-years. Age and known duration of diabetes, mean fasting plasma glucose, and HbA1 levels during the follow-up period were higher in the patients who developed diabetic retinopathy. Of the 56 patients who had nonproliferative diabetic retinopathy at baseline, 11 developed PDR, giving an incidence of 37.5/1,000 person-years. The patients who progressed to PDR during follow-up (progressors) had a higher change of BMI and urinary albumin excretion rate at baseline and a higher mean HbA1 during the follow-up period than the nonprogressors. Cox proportional hazards analysis revealed that mean HbA1 was the only independent risk factor for both the development and progression of diabetic retinopathy.

CONCLUSIONS

The incidence of PDR in Korean NIDDM patients is comparable to that reported in other populations. Poor glycemic control is the most important risk factor for both the development and progression of diabetic retinopathy in NIDDM patients.

Alterations of p16INK4A and p15INK4B genes in gastric carcinomas

BACKGROUND

It has been suggested that cyclin-dependent kinase inhibitors (CDKIs), including p16 and p15, are tumor suppressor genes. Alterations of CDKIs have been found in most types of cancer. However, little is known about the status of p16 and p15 genes, including methylation of the promoter region, in gastric carcinoma.

METHODS

Thirty-six primary gastric tumors and 9 gastric carcinoma cell lines were examined for alterations of the p16 and p15 genes. Deletion of the p16 and p15 genes was assessed by Southern blot analysis, expression by Northern blot analysis, and mutation by polymerase chain reaction-single strand conformation polymorphism followed by direct sequencing. The methylation status of the 5' CpG island of the p16 gene was evaluated using methylation-sensitive restriction enzymes, and reversal of the transcriptional block of the p16 gene was determined by Northern blot analysis after treatment with 5-aza-2'-deoxycytidine.

RESULTS

Homozygous deletions of the p16 and 15 genes from 2 of 9 gastric carcinoma cell lines were found. In contrast, no deletions were detected in 36 primary gastric tumors, and one primary tumor showed rearrangements of the p16 and p15 genes. Two gastric carcinoma cell lines showed a point mutation and an insertional mutation of the p16 gene, respectively; however, no point mutations were noted for the p16 and p15 genes in any of the primary gastric tumors. Constitutive levels of p16 mRNA expression in gastric carcinoma cell lines were quite heterogeneous; four gastric carcinoma cell lines had no detectable p16 mRNA and 6 gastric carcinoma cell lines had negligible expression of p15 mRNA. Of 10 primary gastric tumors, only 1 tumor expressed p16 mRNA. Furthermore, abnormal DNA methylation patterns of the p16 gene were found in 2 gastric carcinoma cell lines through the use of methylation-sensitive restriction enzymes. These cell lines lacked expression of p16 mRNA without deletions of the p16 gene. These transcriptional blocks were reversed by treatment with 5-aza-2'-deoxycytidine.

CONCLUSIONS

Deletions or mutations of the p16 and p15 genes are uncommon in primary gastric carcinomas. However, defective mRNA transcription, sometimes by aberrant DNA methylation, might be one of the pathways of inactivation of the p16 gene that leads to the development of gastric carcinoma.

Alterations of p16INK4A and p15INK4B genes in gastric carcinomas

BACKGROUND

It has been suggested that cyclin-dependent kinase inhibitors (CDKIs), including p16 and p15, are tumor suppressor genes. Alterations of CDKIs have been found in most types of cancer. However, little is known about the status of p16 and p15 genes, including methylation of the promoter region, in gastric carcinoma.

METHODS

Thirty-six primary gastric tumors and 9 gastric carcinoma cell lines were examined for alterations of the p16 and p15 genes. Deletion of the p16 and p15 genes was assessed by Southern blot analysis, expression by Northern blot analysis, and mutation by polymerase chain reaction-single strand conformation polymorphism followed by direct sequencing. The methylation status of the 5' CpG island of the p16 gene was evaluated using methylation-sensitive restriction enzymes, and reversal of the transcriptional block of the p16 gene was determined by Northern blot analysis after treatment with 5-aza-2'-deoxycytidine.

RESULTS

Homozygous deletions of the p16 and 15 genes from 2 of 9 gastric carcinoma cell lines were found. In contrast, no deletions were detected in 36 primary gastric tumors, and one primary tumor showed rearrangements of the p16 and p15 genes. Two gastric carcinoma cell lines showed a point mutation and an insertional mutation of the p16 gene, respectively; however, no point mutations were noted for the p16 and p15 genes in any of the primary gastric tumors. Constitutive levels of p16 mRNA expression in gastric carcinoma cell lines were quite heterogeneous; four gastric carcinoma cell lines had no detectable p16 mRNA and 6 gastric carcinoma cell lines had negligible expression of p15 mRNA. Of 10 primary gastric tumors, only 1 tumor expressed p16 mRNA. Furthermore, abnormal DNA methylation patterns of the p16 gene were found in 2 gastric carcinoma cell lines through the use of methylation-sensitive restriction enzymes. These cell lines lacked expression of p16 mRNA without deletions of the p16 gene. These transcriptional blocks were reversed by treatment with 5-aza-2'-deoxycytidine.

CONCLUSIONS

Deletions or mutations of the p16 and p15 genes are uncommon in primary gastric carcinomas. However, defective mRNA transcription, sometimes by aberrant DNA methylation, might be one of the pathways of inactivation of the p16 gene that leads to the development of gastric carcinoma.

Alterations of p16INK4A and p15INK4B genes in gastric carcinomas

BACKGROUND

It has been suggested that cyclin-dependent kinase inhibitors (CDKIs), including p16 and p15, are tumor suppressor genes. Alterations of CDKIs have been found in most types of cancer. However, little is known about the status of p16 and p15 genes, including methylation of the promoter region, in gastric carcinoma.

METHODS

Thirty-six primary gastric tumors and 9 gastric carcinoma cell lines were examined for alterations of the p16 and p15 genes. Deletion of the p16 and p15 genes was assessed by Southern blot analysis, expression by Northern blot analysis, and mutation by polymerase chain reaction-single strand conformation polymorphism followed by direct sequencing. The methylation status of the 5' CpG island of the p16 gene was evaluated using methylation-sensitive restriction enzymes, and reversal of the transcriptional block of the p16 gene was determined by Northern blot analysis after treatment with 5-aza-2'-deoxycytidine.

RESULTS

Homozygous deletions of the p16 and 15 genes from 2 of 9 gastric carcinoma cell lines were found. In contrast, no deletions were detected in 36 primary gastric tumors, and one primary tumor showed rearrangements of the p16 and p15 genes. Two gastric carcinoma cell lines showed a point mutation and an insertional mutation of the p16 gene, respectively; however, no point mutations were noted for the p16 and p15 genes in any of the primary gastric tumors. Constitutive levels of p16 mRNA expression in gastric carcinoma cell lines were quite heterogeneous; four gastric carcinoma cell lines had no detectable p16 mRNA and 6 gastric carcinoma cell lines had negligible expression of p15 mRNA. Of 10 primary gastric tumors, only 1 tumor expressed p16 mRNA. Furthermore, abnormal DNA methylation patterns of the p16 gene were found in 2 gastric carcinoma cell lines through the use of methylation-sensitive restriction enzymes. These cell lines lacked expression of p16 mRNA without deletions of the p16 gene. These transcriptional blocks were reversed by treatment with 5-aza-2'-deoxycytidine.

CONCLUSIONS

Deletions or mutations of the p16 and p15 genes are uncommon in primary gastric carcinomas. However, defective mRNA transcription, sometimes by aberrant DNA methylation, might be one of the pathways of inactivation of the p16 gene that leads to the development of gastric carcinoma.