The Japanese Study Group of Insulin Therapy for Childhood and Adolescent Diabetes (JSGIT): initial aims and impact of the family history of type 1 diabetes mellitus in Japanese children

The Japanese Study Group of Insulin Therapy for Childhood and Adolescent Diabetes (JSGIT) was established in July 1994 with the chief aim to improve the quality of therapy for type 1 diabetes in children, an entity far less common in Japan than in Europe. We proposed four initial research topics: (i) to determine the current status of medical care and glycemic control in Japanese children with type 1 diabetes mellitus; (ii) to standardize the measurement of hemoglobin A1c; (iii) to establish a registry of a large cohort of patients in order to enable prospective studies to improve the quality of therapy for children with type 1 diabetes in Japan; and (iv) to enable participants of the JSGIT to hold a workshop twice annually. We registered a total of 736 patients from 45 hospitals throughout Japan. Intervention via insulin treatment was instituted after 2 yr for those patients whose hemoglobin A1c level was more than 8.1%. The proportion of patients receiving multiple insulin injections increased after intervention; however, average hemoglobin A1c in females remained significantly higher than in males. We identified two forms of diabetes in Japanese children: a rapidly progressive form and a more slowly progressive form. There was a significantly higher prevalence of a family history of diabetes in first-degree relatives in the slowly progressive form. These preliminary findings are the result of the first collaborative study of childhood diabetes in Japan.

Ethnic disparities in unmet need for alcoholism, drug abuse, and mental health care

OBJECTIVE

Recent policy has focused on documenting and reducing ethnic disparities in availability and quality of health care. The authors examined differences by ethnic status in unmet need for alcoholism, drug abuse, and mental health treatment.

METHOD

Data were from a follow-up survey of adult respondents to a 1996-1997 national survey. Non-Hispanic whites, African Americans, and Hispanics were compared in access to alcoholism and drug abuse treatment and mental health care (primary or specialty), unmet need for care, satisfaction with care, and use of active treatment for alcoholism, drug abuse, and mental health problems in the prior 12 months.

RESULTS

A total of 31.9% of whites, 28.1% of African Americans, and 30.1% of Hispanics had some alcoholism, drug abuse, and mental health care, mostly in primary care. Among those with perceived need, compared to whites, African Americans were more likely to have no access to alcoholism, drug abuse, or mental health care (25.4% versus 12.5%), and Hispanics were more likely to have less care than needed or delayed care (22.7% versus 10.7%). Among those with need, whites were more likely than Hispanics or African Americans to be receiving active alcoholism, drug abuse, or mental health treatment (37.6% versus 22.4%-25.0%).

CONCLUSIONS

The authors document greater unmet need for alcoholism and drug abuse treatment and mental health care among African American and Hispanics relative to whites. New policies are needed to improve access to and quality of alcoholism, drug abuse, and mental health treatment across diverse populations.

Effects of dobutamine on critical capillary PO(2) and lactic acidosis threshold in patients with cardiovascular disease

BACKGROUND

Muscle capillary PO(2) has been found to reach a minimal value, ie, a critical capillary PO(2), in the midrange of work capacity in patients with cardiovascular disease. However, it is not known if the critical capillary PO(2) can be influenced by a change in blood flow response to exercise. This study was carried out to determine the effect of changing the blood flow response to exercise, using low-dose infusion of dobutamine, on muscle end-capillary PO(2) (as approximated by femoral vein PO(2)), lactate concentration, oxygen uptake (O(2)), and the relation among these variables.

METHODS

Eleven male patients with coronary artery disease performed an incremental exercise test on a cycle ergometer with and without continuous infusion of dobutamine, 6 microg/kg/min. Respiratory gas analysis was performed on a breath-by-breath basis; femoral vein blood was sampled every minute through a percutaneous catheter.

RESULTS

Dobutamine increased resting O(2) and O(2) at the lactic acidosis threshold (LAT) but not peak O(2). The femoral vein PO(2) rapidly decreased toward a minimal value with increasing work rate (O(2)) irrespective of the infusion of dobutamine. After reaching its nadir (critical PO(2)), femoral vein lactate began to increase without further decrease in PO(2). Infusion of dobutamine significantly increased femoral vein resting PO(2) (27.4 +/- 4.9 mm Hg vs 32.5 +/- 3.8 mm Hg) and critical PO(2) (20.5 +/- 1.5 mm Hg vs 21.9 +/- 1.7 mm Hg), but not the PO(2) at peak O(2) (22.1 +/- 3.3 mm Hg vs 22.0 +/- 2.9 mm Hg).

CONCLUSIONS

Infusion of dobutamine was found to raise the critical PO(2) and LAT but not peak O(2). These findings suggest that some of the acute increase in blood flow induced by dobutamine infusion benefits exercising muscle by increasing capillary PO(2), thereby delaying the onset of lactic acidosis.

Expression and chromosome location of hamster Ku70 and Ku80

Ku proteins play an important role in DNA double-strand break (DSB) repair, chromosome maintenance, and growth regulation. To understand the fundamental characteristics of Ku proteins, we examined the electrophoretic mobility and expression of hamster Ku70 and Ku80 and determined the chromosome locations of their genes. The electrophoretic mobility of hamster Ku proteins are different from that of human Ku proteins. No significant changes in the quantity of Ku proteins were observed in CHO-K1 cells treated with 10 Gy of ionizing radiation, suggesting that both proteins are expressed constitutively in amounts adequate to repair DNA DSBs. The chromosome locations of the Ku genes were determined by direct R-banding fluorescence in situ hybridization. The Ku70 gene was localized to Syrian hamster chromosome 4qa4.1--> qa4.2 and Chinese hamster chromosome 2p3.1, and the Ku80 gene was localized to Syrian hamster chromosome 4qb5--> qb6.1 and Chinese hamster chromosome 2p3.5-->p3.6. These results provide clues to the biological functions of Ku, as well as useful information for constructing comparative chromosome maps between hamsters and other mammalian species, including human, mouse, and rat.

Comparative effects of dietary fat types on hepatic enzyme activities related to the synthesis and oxidation of fatty acid and to lipogenesis in rats

The effects of different types of dietary fat on the activities of hepatic enzymes related to fatty acid synthesis [glucose-6-phosphate dehydrogenase (G6PDH) and acetyl-CoA carboxylase (ACC)], oxidation [acyl-CoA synthetase (AST), carnitine palmitoyl transferase (CPT), and peroxisomal beta-oxidation (PbetaOX)], and lipogenesis [phosphatidate phosphohydrolase (PAP), diacylglycerol acyltransferase (DGAT), and phosphocholine diacylglycerol transferase (PCDGT)], and plasma and liver lipid levels were investigated in male Wistar rats. The animals were 6 weeks old and about 120 g of body weight, and were fed on test diets containing 20% of a mixture of tripalmitin, tristearin and corn oil (SFA), olive oil (OLI), sunflower oil (SUN), linseed oil (LIS), and sardine oil (SAR) for 2 weeks. The concentrations of plasma total cholesterol (T-CHOL), high-density lipoprotein-cholesterol (HDL-CHOL), triacylglycerol (TG) and phospholipid (PL) were generally higher in the rats fed on SFA and OLI than in those given SUN, LIS and SAR. The rats fed on OLI had a higher level of liver T-CHOL than those fed on the other fats. The liver TG content was nearly higher from the intake of SFA and OLI than from SUN, LIS and SAR, although the liver PL level was not affected by the type of dietary fat. The SFA and OLI groups had the highest activities of hepatic G6PDH and ACC, and the SAR group, the lowest activities. The activities of AST and CPT, and peroxisomal PbetaOX in the liver were higher in the rats fed on the LIS and SAR diets than in those given the other diets. The hepatic PAP activity was higher from the intake of OLI and SUN, and tended to be higher from SFA than from LIS and SAR. The activity of liver DGAT was higher from SFA and inclined to be higher from OLI, SUN, and LIS than from SAR, while the PCDGT activity in the liver was not effected by the type of dietary fat. The concentrations of plasma and liver TG were generally positively correlated with the activities of liver enzymes related to the synthesis of fatty acids and lipids, and negatively with those involved in fatty acid oxidation. Based on these results, it is suggested that the levels of plasma and liver TG were controlled by different types of dietary fat through changes in the hepatic enzyme activities related to fatty acid synthesis, lipogenesis, and fatty acid oxidation.

Collaborative interventions for physically injured trauma survivors: a pilot randomized effectiveness trial

Posttraumatic behavioral and emotional disturbances occur frequently among physically injured hospitalized trauma survivors. This investigation was a pilot randomized effectiveness trial of a 4-month collaborative care intervention for injured motor vehicle crash and assault victims. As surgical inpatients, intervention subjects (N=16) were assigned to a trauma support specialist who provided counseling, consulted with surgical and primary care providers, and attempted postdischarge care coordination. Control subjects (N=18) received usual posttraumatic care. For all participants, posttraumatic stress disorder (PTSD) and depressive symptoms, episodic alcohol intoxication, and functional limitations were evaluated during the hospitalization and 1 and 4 months postinjury. Study logs and field notes revealed that over 75% of intervention activity occurred in the first month after the trauma. One-month post-trauma intervention subjects when compared to controls demonstrated statistically significant decreases in PTSD symptoms as well as a reduction in depressive symptoms. However, at the 4-month assessment, intervention subjects evidenced no significant improvements in PTSD and depressive symptoms, episodic alcohol intoxication, or functional limitations. Future larger scale trials of stepped collaborative care interventions for physically injured trauma survivors are recommended.

Dimerization and nuclear localization of ku proteins

Ku, a heterodimer of Ku70 and Ku80, plays a key role in multiple nuclear processes, e.g. DNA repair, chromosome maintenance, and transcription regulation. Heterodimerization is essential for Ku-dependent DNA repair in vivo, although its role is poorly understood. Some lines of evidence suggest that heterodimerization is required for the stabilization of Ku70 and Ku80. Here we show that the heterodimerization of these Ku subunits is important for their nuclear entry. When transfected into Ku-deficient xrs-6 cells, exogenous Ku70 and Ku80 tagged with green fluorescent protein accumulated into the nucleus, whereas each nuclear localization signal (NLS)-dysfunctional mutant was undetectable in the nucleus, supporting the idea that each Ku can translocate to the nucleus through its own NLS. On the other hand, the nuclear accumulation of each NLS-dysfunctional mutant was markedly enhanced by the presence of an exogenous wild-type counterpart. In Ku-expressing HeLa cells, each NLS-dysfunctional mutant, as well as wild-type Ku70 and Ku80, was still detectable in the nucleus, whereas the double mutant of each Ku subunit with decreased functions of both nuclear targeting and dimerization was undetectable in the nucleus. Our results indicate that each Ku subunit can translocate to the nucleus not only through its own NLS but also through heterodimerization with each other.

Prognostic significance of cardiopulmonary exercise testing for 10-year survival in patients with mild to moderate heart failure

Although a number of studies have investigated the prognostic significance of exercise variables, they have focused only on short-term prognosis in relatively severe heart failure. This study was carried out to determine whether the indices obtained during cardiopulmonary exercise testing have prognostic significance during a 10-year follow-up in mild to moderate heart failure. Three hundred and sixty-four consecutive patients with cardiac disease performed 4 min of 20-W warm-up, followed by a symptom-limited incremental exercise test on a cycle ergometer. In addition to the measurements of peak oxygen uptake (VO2) and gas exchange (anaerobic) threshold, the time constant of VO2 kinetics during the onset of warm-up exercise was calculated using a single exponential equation. Data on mortality were available for follow-up in 260 patients. After 3,331+/-610 days of follow-up, 29 cardiovascular-related deaths occurred. The time constant of VO2 in the nonsurvivors was 76.7+/-43.3 s and was significantly prolonged compared with that of survivors (55.3+/-30.6 s, p=0.001). Peak VO2 and gas exchange threshold were both significantly lower in nonsurvivors than in survivors. Kaplan-Meier survival curves for 10 years of follow-up demonstrated a survival rate of 89.0% for patients with a normal VO2 time constant (< 80 s) and 71.7% for those with a longer time constant (> or = 80 s), showing a significant difference in survival (p=0.0028). Respiratory gas parameters obtained during exercise testing, particularly the time constant of VO2 kinetics, were found to be useful for predicting long-term prognosis in patients with chronic heart failure. These results suggest that cardiopulmonary exercise testing could be more applicable in ambulatory patients with minimal symptoms or minimal functional impairment.

Cyclic malyl anthocyanins in Dianthus caryophyllus

3,5-Di-O-(beta-glucopyranosyl) pelargonidin 6''-O-4,6'''-O-1-cyclic malate and a previously reported cyanidin equivalent, 3,5-di-O-(beta-glucopyranosyl) cyanidin 6''-O-4,6'''-O-1-cyclic malate were identified from petals of deep pink and red-purple flower cultivars of Dianthus caryophyllus, respectively.

Optimum duration of oral adjuvant chemotherapy of HCFU for colorectal cancer; review of 5-year follow-up

PURPOSE

To investigate the optimal duration of oral HCFU administration for minimization of side effects induced by long-term administration.

PATIENTS AND METHODS

In total, 155 patients allocated to two groups of different duration of the therapy were reviewed: twice or three times per day doses of oral HCFU (8 mg/Kg body weight/day) for 3 months vs. 12 months.

RESULTS

Though statistically significant difference was not found in cumulative survival and disease-free rates between the groups due to so many violations of duration of therapy, when reanalyzing the variables in order of real duration of therapy, those rates were significantly higher in patients treated for 300 and more days than less than 300 days (g-Wilcoxon test: p < 0.04). No significant difference was observed in the background factors between the groups.

CONCLUSION

At least 300 days is suggested to be necessary to obtain the optimal effectiveness of adjuvant chemotherapy for curatively resected colorectal cancer.

Impaired heart rate response during incremental exercise in patients with acute myocardial infarction and after coronary artery bypass grafting: evaluation of coefficients with Karvonen's formula

Heart rate (HR) response during exercise in patients with ischemic heart disease was evaluated, and the appropriateness of Karvonen's method for determining rehabilitation exercise target HR was investigated. The study group comprised 24 patients with acute myocardial infarction (AMI) and 37 patients who had undergone coronary artery bypass grafting (CABG). Cardiopulmonary exercise testing (CPX) was performed with a cycle ergometer and changes in HR (deltaHR)/changes in work rate (deltaWR) and interval changes of the coefficient of Karvonen's formula were evaluated. In the AMI group and the CABG group, deltaHR/deltaWR were significantly lower than those of age-matched control subjects (p<0.01). Karvonen's coefficients ranged from 0.37 to 0.54 when calculated from actual peak HR and 0.21 to 0.32 calculated from the predicted peak HR. An impaired HR response was found in patients with AMI and those who had had CABG up to 6 months previously. Because the Karvonen's coefficient values, which ranged from 0.6 to 0.8, were elevated for these patients, and considering the data from the CPX, increased exercise is recommended for such cases.

Effects of physical training on the recovery of the autonomic nervous activity during exercise after coronary artery bypass grafting: effects of physical training after CABG

Analysis of heart rate variability (HRV) can identify patients at risk of sudden cardiac death after myocardial infarction. The present study examined the effect of 2 weeks of supervised aerobic exercise training on the recovery of the autonomic nervous activity, exercise capacity, and cardiac output (CO) after coronary artery bypass grafting (CABG). Twenty-eight patients were randomly divided into the training group or the control group and performed exercise tests at 1 week, 3 weeks, 3 months, 6 months and 1 year after CABG. The HRV was measured, and the high-frequency component of HRV was used as an index of parasympathetic nerve activity (PNA); the plasma norepinephrine concentration (NE) was used as an index of sympathetic nervous activity. Cardiac output was also measured. In the training group, peak VO2, peak CO and PNA during exercise had improved at 3 weeks, but there was no improvement in these indices in the control group. NE decreased 1 week after CABG in both groups. These results indicate that physical training soon after CABG improves not only the exercise capacity, but also PNA.

Ku70 can translocate to the nucleus independent of Ku80 translocation and DNA-PK autophosphorylation

Ku plays an important role in multiple nuclear processes, e.g., DNA repair, chromosome maintenance, and transcriptional regulation. Although some evidence suggests that the nuclear translocation of Ku plays a key role in regulating the function of Ku, the mechanism is poorly understood. Using the site-directed mutagenesis technique, we demonstrate here that Ku70 can translocate to the nucleus without heterodimerization with Ku80. The nuclear accumulation of Ku70 mutants of the nuclear localization signal, which retained their binding ability with Ku80, was diminished. On the other hand, Ku70 mutants which lacked the ability to bind with Ku80 could translocate to the nuclei. Human Ku70, when transfected, accumulated within the nuclei of hamster xrs-6 cells which had undetectable DNA-PK activity and Ku80. Ku70 and Ku80 mutants of DNA-PK phosphorylation sites showed normal heterodimerization and nuclear translocation. These findings also support the idea that Ku70 can translocate to the nucleus independent of DNA-PK autophosphorylation.

Accuracy and repeatability of blood volume measurement by pulse dye densitometry compared to the conventional method using 51Cr-labeled red blood cells

OBJECTIVE

To determine the accuracy and repeatability of pulse dye densitometry (PDD) in measuring blood volume (BV) by comparing it with the conventional method using 51Cr-labeled red blood cells (RI method) and by assessing sequential measurements.

DESIGN

Prospective clinical study.

SETTING

University hospital.

PATIENTS AND PARTICIPANTS

Eleven adult ICU patients who received cardiac surgery (1st ICU day).

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

After injecting indocyanine green (10 or 20 mg) into the right atrium, its arterial concentration was continuously monitored at the nose and finger by PDD, and BV was calculated by back extrapolating the logarithmic dye concentration on the dye elimination curve between 2.5 and 5.5 min after mean transit time to each mean transit time with the least squares method. These measurements were repeated in eight patients and performed only once in the other three, and the BV was measured concurrently by the RI method one time. The Bland-Altman method was used for evaluating differences between methods and within methods. The (percentage) biases and standard deviations between the PDD and RI methods and between the successive measurements by PDD at the finger and nose were 0.26 +/- 0.491 (8.8 +/- 15.3%) and 0.004 +/- 0.251 (0.06 +/- 5.9%) with the probe on a nostril, and 0.16 +/- 0.561 (2.5 +/- 14.4%) and 0.19 +/- 0.311 (4.7 +/- 7.3%) using the finger probe. The bias between methods was less than 10%, and the repeatability of PDD was better.

CONCLUSIONS

As PDD can measure BV with good repeatability and with a small bias compared to the RI method, serial changes in BV can be evaluated at the bedside of critically ill patients noninvasively and repeatedly.

Lack of a relation between serum potassium concentration and exercise hyperpnea in patients with chronic heart disease

Exertional dyspnea, a major symptom of patients with chronic heart failure, mainly stems from an abnormally high ventilatory response to exercise. However, there has been considerable controversy surrounding the mechanisms of respiratory control during exercise, especially regarding the role of serum potassium. We investigated the relation between serum potassium concentration [K+] and ventilation (VE) during exercise before and after oral supplements of potassium chloride in cardiac patients. Thirteen patients with chronic heart disease performed a 6-min constant-work-rate exercise (65.8+/-11.1 W) with respiratory gas measurements before initiating oral supplements of potassium chloride, 4 weeks after continued supplements, and 4 weeks after discontinuing supplements. Blood was sampled from a forearm vein at rest before exercise and at the end of exercise for measurement of [K+] and blood gases. The [K+] at rest was 3.66+/-0.30 mmol/L before oral supplements of potassium and significantly increased to 4.08+/-0.31 mmol/L (p<0.01) after supplements. In spite of the significant increases in the [K+], resting VE was not changed. While serum [K+] during exercise was significantly higher after potassium supplements than before, exercise VE was not influenced by the changes in [K+] throughout the study period. The findings of the present study strongly suggest that the chronic increase in the serum [K+] has no influence on the resting or exercise VE in patients with heart disease.

Percutaneous transluminal coronary angioplasty improves oxygen uptake kinetics during the onset of exercise in patients with coronary artery disease

STUDY OBJECTIVES

Although percutaneous transluminal coronary angioplasty (PTCA) is known to have beneficial effects on exercise capacity, its effects on the cardiovascular response during the onset of exercise have not been clarified. The present study was undertaken to determine the effects of PTCA on the kinetics of oxygen uptake (VO(2)) during constant-work-rate exercise in patients with coronary artery disease, as well as on their indexes of maximal work capacity.

METHODS

Seventeen patients with coronary artery disease who received successful PTCAs performed a 50-W constant-work-rate exercise test for 6 min and a symptom-limited incremental exercise test both before and 4 months after the PTCA procedure. VO(2) was calculated from breath-by-breath analysis of respired gases. The time constant of VO(2) kinetics during the onset of 50-W exercise was determined by fitting a single exponential function to the VO(2) response.

RESULTS

In 14 patients without coronary restenosis, the time constant of VO(2) kinetics was significantly shortened from (mean +/- SD) 57.4 +/- 12.6 before PTCA to 48.2 +/- 9.5 s after PTCA (p = 0. 0035), indicating improved kinetics of the VO(2) response. In these subjects, the peak VO(2) obtained during maximal exercise testing also increased from 23.1 +/- 3.5 to 26.5 +/- 3.2 mL/min/kg, respectively (p = 0.0005). However, there was no improvement in these indexes in the patients who had restenosis after undergoing PTCA (n = 3).

CONCLUSION

Indexes of cardiopulmonary exercise testing, which reflect an efficiency of oxygen flow to the exercising muscle, can be used as an objective, noninvasive, and cost-effective guide for understanding which patients will not have coronary restenosis following PTCA.

Utilization management in a large managed behavioral health organization

OBJECTIVE

The utilization management process of a managed behavioral health organization was examined to determine the frequency and types of reviews and the extent to which rationing of service was achieved through the denial of services.

METHODS

A case study of the utilization management program of a large managed behavioral health organization was done. Information was gathered from claims for 1997, and utilization review data were drawn from 51 plans. Data were examined by review type and authorization actions.

RESULTS

The utilization management program performed a total of 9, 639 reviews. The most common type was concurrent review for additional outpatient therapy visits (46 percent). The second most common type was concurrent facility review (12.9 percent). The vast majority of authorizations were approved at the level requested by the provider (91.8 percent). Very few services were denied (.8 percent) or approved at a level lower than requested by the provider (1.3 percent).

CONCLUSIONS

Although concerns have been raised about the high denial rates of utilization management programs, this study found very low denial rates. Further studies are needed to determine the precise mechanisms used in utilization management programs to control utilization. In addition, the large number of reviews raises questions about the time and opportunity costs of the review process.

A phase III randomized study comparing doxifluridine and 5-fluorouracil as supportive chemotherapy in advanced and recurrent gastric cancer

We conducted a phase III randomized study to investigate effects of supportive chemotherapy with oral doxifluridine (group A, 75 patients) or 5-fluorouracil (group B, 75 patients) in advanced gastric cancer when intensive chemotherapy was not an option. Although there were no significant differences between the groups with regard to survival, hospital-free survival and time to progression, median values of 3 endpoints were superior in group A. Secondary analysis showed that group A patients with prior chemotherapy tended to have longer survival and hospital-free survival and significantly longer time to progression.

Effects of 'cool-down' during exercise recovery on cardiopulmonary systems in patients with coronary artery disease

The effects of 'cool-down' during exercise recovery on cardiovascular and respiratory systems have not been fully clarified. The recovery of respiratory gasses was compared in cardiac patients after maximal exercise during which subjects either performed a cool-down or rested. Twenty-one patients (61+/-10 years) with coronary artery disease performed 2 symptom-limited incremental exercise tests on a cycle ergometer: one with a cool-down and the other without during recovery from the maximal exercise test. Expired gasses were analyzed on a breath-by-breath basis throughout the test and for 6min of recovery. Without a cool-down, the ventilatory equivalent for O2 (VE/O2) increased dramatically during recovery compared with the resting values or those of peak exercise: 44.5+/-7.7 at rest, 44.0+/-10.6 at peak exercise and 63.3+/-14.5 after 2min of recovery. End-tidal PO2 (P(ET)O2) also increased significantly during recovery. However, the overshoot phenomenon of these variables was attenuated when cool-down exercise was performed during recovery. The high ratio of VE/VO2 reflects ventilation perfusion (VA/Q) unevenness and P(ET)O2 is an index of arterial PO2. Thus, it is suggested that cool-down exercise during recovery after maximal exercise testing provides beneficial effects on the respiratory system by decreasing the VA/Q unevenness and relative hyperventilation that are observed when cool-down exercise is not performed.

Differential subcellular localization of DNA-dependent protein kinase components Ku and DNA-PKcs during mitosis

The Ku protein is a complex of two subunits, Ku70 and Ku80. Ku plays an important role in DNA-PKcs-dependent double-strand break repair and V(D)J recombination, and in growth regulation, which is DNA-PKcs-independent. We studied the expression and the subcellular localization of Ku and DNA-PKcs throughout the cell cycle in several established human cell lines. Using immunofluorescence analysis and confocal laser scanning microscopy, we detected Ku70 and Ku80 in the nuclei in interphase cells. In mitotic cells (1) most of Ku protein was found diffused in the cytoplasm, (2) a fraction was detected at the periphery of condensed chromosomes, (3) no Ku protein was present in the chromosome interior. Association of Ku with isolated chromosomes was also observed. On the other hand, DNA-PKcs was detected in the nucleus in interphase cells and not at the periphery of condensed chromosomes during mitosis. Using indirect immunoprecipitation, we found that throughout the cell cycle, Ku70 and Ku80 were present as heterodimers, some in complex with DNA-PKcs. Our findings suggest that the localization of Ku at the periphery of metaphase chromosomes might be imperative for a novel function of Ku in the G(2)/M phase, which does not require DNA-PKcs.

Effects of posture on left ventricular diastolic filling during exercise

BACKGROUND

Measuring the transmitral flow velocity with Doppler echocardiography is a useful method for evaluating left ventricular diastolic function. However, there are few data regarding the effect of posture during exercise on transmitral flow velocity.

METHODS

The transmitral flow velocity with pulsed-wave Doppler echocardiography was measured during supine and upright bicycle ergometer exercise in 10 normal young men without cardiac disease (26.7 +/- 5.5 yr).

RESULTS

The ratio of the early rapid filling wave to the atrial filling wave (E/A) was gradually decreased with increasing exercise intensity. At rest and during recovery, the E/A ratio was significantly higher (P < 0.01) in the supine position than in the upright position. This difference was caused mainly by the higher E wave in the supine position. However, E wave and E/A ratio did not differ between the upright and supine position during exercise.

CONCLUSION

Although measurement of left ventricular filling is completely noninvasive and clinically useful for evaluating diastolic function, it was found that the E/A ratio was profoundly influenced by posture and exercise intensity. These results suggest that the potential influences of posture and exercise intensity on the filling velocities should be taken into account when interpreting diastolic function by Doppler echocardiography.

Mechanism of overshoot in cardiac function during recovery from submaximal exercise in man

BACKGROUND

A sudden increase (overshoot) in the left ventricular ejection fraction during the recovery from maximal exercise has been reported in patients with coronary artery disease, but its mechanism has not been fully clarified. We investigated whether this phenomenon may occur in normal subjects, and whether it depends on the intensity of exercise.

METHODS

Thirteen normal subjects (mean [+/- SD] age, 59 +/- 8 years old) performed two levels (25 W and 50 W) of mild-intensity, constant-work-rate exercise for 6 min on a cycle ergometer. Left ventricular function was monitored continuously during the recovery from exercise using a computerized cadmium telluride detector.

RESULTS

An overshoot was observed in the ejection fraction during the first minute of recovery compared with the end-exercise value. The overshoot in the ejection fraction during recovery after the 50-W exercise was greater than that seen after the 25-W exercise. An overshoot phenomenon in stroke volume was also observed during the recovery from 50-W exercise.

CONCLUSIONS

The overshoot in cardiac function observed during the early phase of recovery, which was caused mainly by an immediate decrease in end-systolic volume, occurred even after exercise of mild intensity. This phenomenon appears to suggest the existence of a transient mismatch between cardiac contractility and afterload reduction during the recovery from mild-intensity exercise, even in normal subjects.

Kinetics of pulmonary gas exchange during and while recovering from exercise in patients after anterior myocardial infarction

The effect of exercise intensity on gas exchange kinetics was investigated during exercise and recovery, as well as the relationship between the kinetics during exercise and recovery. Twenty-three patients with a history of anterior myocardial infarction performed low-intensity (38.7+/-8.3 W) and high-intensity (68.8+/-15.0 W) exercise for 6 min. The time constants of oxygen uptake (VO2), carbon dioxide output (VCO2) and minute ventilation (VE) were significantly prolonged during high intensity exercise compared with low-intensity exercise (61.2+/-8.6 vs 52.3+/-10.3 s, p<0.005 for the time constant of VO2). The time constant of VO2 was similar during exercise and during recovery from exercise of high (61.2+/-8.6 vs 66.2+/-12.2 s) as well as low intensity (52.3+/-10.3 vs 55.0+/-10.1 s). However, the time constants of VCO2 and heart rate were significantly shorter during recovery than during exercise. The time constants of VCO2 and VE were significantly longer than that of VO2 during both exercise and recovery. In the present study, it was found that (1) the gas exchange kinetics were influenced by the intensity of exercise; (2) the kinetics during recovery did not necessarily reflect the kinetics during exercise except for VO2; and (3) the kinetics of VCO2 and VE were delayed as compared with the VO2 kinetics. These characteristics should be taken into account when using gas exchange kinetics to estimate cardiopulmonary responses to exercise in patients with left ventricular dysfunction.

Novel missense mutation (Leu466Arg) of the DAX1 gene in a patient with X-linked congenital adrenal hypoplasia

We identified a DAX1 missense mutation, a substitution of arginine for leucine at codon 466 (Leu466Arg), in an infant with X-linked congenital adrenal hypoplasia (AHC). A heterozygous substitution, Leu466Arg, was also identified in his mother and sister. Since leucine at position 466 is well conserved among other orphan nuclear hormone receptor superfamilies and Leu466Arg was not detected among 50 normal Japanese control individuals, the mutation is most likely responsible for X-linked AHC. It is interesting to note that Leu466Arg among all mutations ever reported is located at the most C-terminal region of the DAX-1 protein. Most mutations identified previously were located in the C-terminal presumptive ligand binding domain. Hence, the C-terminal end of the DAX-1 protein may play an important role in the biological function, such as in normal adrenal embryogenesis.

The prevalence of mitochondrial gene mutations in childhood diabetes in Japan

To investigate the prevalence of mitochondrial DNA mutations among Japanese children with IDDM as well as in those with NIDDM, a total of 155 patients with IDDM and 30 patients with NIDDM who were younger than 15 years of age at onset were studied for the following mtDNA mutations: 1) the A-->G mutation at position 3243 of mitochondrial leucine transfer RNA (3243 mutation); 2) the G-->A mutation at position 3316 of mitochondrial leucine transfer RNA (3316 mutation), and 3) The T-->C mutation at position 3394 of the mitochondrial NADH dehydrogenase subunit (3394 mutation). None of the 155 IDDM patients had the 3243 mutation. Although two of the 155 IDDM patients had homoplasmy of 3316 and five had 3394 mutations, these frequencies were not significant compared with healthy controls. None of the 30 NIDDM patients had the 3243, 3316 or 3394 mutation. The presence of these mutations even in control subjects suggests that the effect of the 3316 or 3394 mutation on mitochondrial function is relatively mild. It seems that 3316 and 3394 mutations contribute to the manifestation of diabetes together with other genetic and/or environmental factors.