Familial Alzheimer's disease-associated mutations block translocation of full-length presenilin 1 to the nuclear envelope

A polyclonal antibody, M5, to the hydrophilic loop domain of human presenilin 1 (PS1) was prepared. Western blot and immunoprecipitation analyses showed that M5 specifically recognized the processed C-terminal fragment, but not the full-length PS1. Epitope mapping analysis revealed that the essential sequence for recognition of the C-terminal fragment by M5 is DPEAQRR (302-308). The recognition of the C-terminal fragment by M5 in a processing-dependent manner was further confirmed by competitive enzyme-linked immunosorbent assay using the synthetic peptide L281 (281-311), which contains the putative processing site and the preceding amino acids to the site. Although L281 contains the epitope sequence for M5, the maximum inhibition was only 14%. Immunocytochemistry using M5 combined with hL312, which recognizes both full-length PS1 and the C-terminal fragment, allowed us to distinguish the localization of the processed C-terminal fragment from that of full-length PS1. Confocal microscopy demonstrated that the full-length form of wild-type PS1 is preferentially located in the nuclear envelope, while the processed C-terminal fragment is mainly present in the endoplasmic reticulum (ER). However, PS1 with familial Alzheimer's disease-associated mutations could not translocate to the nuclear envelope, and both the full-length and processed mutants were co-localized in the ER.

Efficacy of primary percutaneous transluminal coronary angioplasty for acute myocardial infarction in patients aged > or = 80 years

The therapeutic result of primary percutaneous transluminal coronary angioplasty (PTCA) in the elderly was assessed in 20 of 44 patients > or = 80 years old (range 81-92 years, mean age 84 +/- 3 years) with acute myocardial infarction who underwent primary PTCA and the results compared with 194 younger patients (< 80 years) who underwent primary PTCA during the same period. In-hospital prognosis, and long-term outcomes were investigated. Emergency coronary angiography was performed in 47.7% of the patients with acute myocardial infarction in the elderly group with 45.5% receiving primary PTCA. Primary PTCA was successful in 95.0% of the elderly group, showing no significant difference from the younger group. In-hospital mortality showed no significant difference between the elderly group and the younger group (5.0% vs 4.1%). However, the incidences of pump failure of the heart and bleeding complication requiring blood transfusion were higher in the elderly group during hospitalization. The 2-year survival rate for the elderly group was 82.5 +/- 9.3%, which was better than previous studies. These results suggest that primary PTCA has a good success rate in the elderly patients with acute myocardial infarction, and decreases the in-hospital mortality and improves the long-term outcome. However, this study was conducted retrospectively in a small group of patients. The efficacy of primary PTCA for the elderly remains to be clarified in a larger prospective trial.

Magnesium dynamics and relation to left ventricular function in acute myocardial infarction

The present study investigated the serial changes in serum magnesium (Mg) and erythrocyte concentration of Mg in patients with acute myocardial infarction (AMI) and the relationship between these changes and left ventricular ejection fraction (LVEF) at 1 month after the onset of infarction. The study group comprised 26 patients with AMI (mean age, 57.9+/-8.9 years). Serum Mg and erythrocyte Mg were measured on hospital days 1, 2, 4, 7 and 21. The change in erythrocyte Mg during the acute phase was calculated as a ratio: [(erythrocyte Mg at day 2)-(erythrocyte Mg at day 1)]/(erythrocyte Mg at day 1). The change in serum Mg was calculated similarly. The following results were obtained. (1) Serum Mg tended to increase from the onset of myocardial infarction (day 1: 1.86+/-0.19, day 2: 1.93+/-0.22, day 4: 2.17+/-0.23; day 7: 2.25+/-0.20; day 21: 2.12+/-0.15 mg/dl). (2) Erythrocyte Mg on day 2 and day 4 showed a significant decrease compared with day 1 (day 1: 2.45+/-0.40, day 2: 2.09+/-0.41, day 4: 2.07+/-0.37, day 7: 2.22+/-0.33, day 7: 2.34+/-0.28 mg/dl per 400x10(4)/mm3 cells). (3) A significant positive correlation was observed between the change in serum Mg and LVEF (r=0.55, p<0.05), and a significant negative correlation was observed between the change in erythrocyte Mg and LVEF (r=-0.57, p<0.05). Thus, it was concluded that an extracellular shift in intracellular Mg occurred during the first 2 days after the onset of myocardial infarction. This responsive increase in the extracellular Mg level may be an important factor for maintaining left ventricular function in patients 1 month after the onset of AMI.

Effectiveness of a CD-ROM multimedia tutorial in transferring cognitive knowledge essential for laparoscopic skill training

BACKGROUND

Computer-assisted instruction (CAI) can benefit surgical education by improving efficiency, effectiveness, standardization, and access. This study compares knowledge gains for laparoscopic skill acquisition following a standardized tutorial delivered via CD-ROM versus live instructor.

METHODS

A standardized tutorial was written and subsequently converted to multimedia CD-ROM format by its author (JR). During a laparoscopic development course, experienced US-trained surgeons (n = 52) participated in the tutorial delivered live by the author. The CD-ROM tutorial replaced the instructor for the following groups: (1) experienced US-trained surgeons (n = 27); (2) US-trained surgical residents (n = 59); and (3) Greek surgeons (n = 63). A 51-item knowledge test was administered before and after tutorial instruction.

RESULTS

The mean increase in scores between pretest and posttest was significant (P <0.01) and of similar magnitude in each group, with nonsignificant posttest mean differences among US-trained groups.

CONCLUSIONS

The CD-ROM tutorial effectively transfers cognitive information necessary for skill development. Distance learning modes of this tutorial program may be feasible.

Bronchial brushing cytology features of primary malignant fibrous histiocytoma of the lung. A case report

BACKGROUND

Malignant fibrous histiocytoma (MFH) of the lung is rare. Early diagnosis is very important because of its poor prognosis. Long-term survivors of pulmonary MFH are patients who had surgical resection. When the patient can undergo surgery after a prompt diagnosis, the prognosis improves more than with other therapy. However, it is not easy to establish the diagnosis of thoracic MFH. In general, the small fragments from bronchial or percutaneous transthoracic fine needle aspiration (FNA) biopsies are inadequate for cytologic or pathologic analysis. Bronchial brushing cytology is greatly superior to FNA cytology because one can obtain a large amount of cells. Therefore, bronchial brushing cytology may play a useful role in diagnosis when endobronchial involvement is found.

CASE

A 65-year-old female was admitted with a cough, yellow sputum and exertional dyspnea. A chest roentgenogram showed a 12 x 12-cm mass in the left lung field. Bronchial brushing cytology revealed many fibroblastlike, histiocytelike, bizarre and multinucleated giant cells in a background of necrosis. Atypical mitotic figures were also found. The cytologic findings strongly suggested MFH. Although the pathologic findings from FNA biopsy showed storiform clusters structured by pleomorphic, fibroblastlike cells with bizarre nuclei and mitotic figures, the material was too small to diagnose it definitively. Six months later the patient died. An autopsy confirmed the diagnosis of MFH: the typical storiform clusters were composed of many fibroblastlike and histiocytelike cells that were positive for CD68 (PGM1) antibody.

CONCLUSION

Bronchial brushing cytology may be a useful method for early, definitive diagnosis of MFH. The presence of pleomorphic, spindle-shaped fibroblastlike and histiocytelike cells with the clusters showing a storiform pattern may permit the diagnosis of MFH.

[Small adenocarcinoma of the lung under long-term observation]

A 68-year-old man presented with symptoms of common cold at our hospital on March 8, 1995. Ground glass opacity (GGO) was detected in the right S 4 a by high resolution computed tomography (HRCT) during a routine examination. Except for mild traction of the nearest pleura, the lesion itself demonstrated little change on HRCT images for 2 years. HRCT images disclosed slight enlargement of the lesion over a long-term period of follow-up observation. Exactly 25 months after the first examination, HRCT scans demonstrated an area of centralized dense concentration. Right middle lobectomy was performed 30 months after the lesion was first detected. Pathologic findings from the resected specimen revealed Noguchi's small adenocarcinoma of the lung (type B classification: localized bronchioloalveolar carcinoma with collapse of alveolar structure). The lesion was scanned 8 times with HRCT during the follow-up period. The change to GGO with centralized density and spicula was observed in detail, and thought to be evidence of a progression from type A to type B. We concluded that a set of fixed settings should be utilized for repeated HRCT examinations of small peripheral lesions exhibiting GGO.

Suppression of cellular immunity by surgical stress

BACKGROUND

Suppression of cellular immunity is one of the host responses to surgical stress. In cancer patients this immunosuppression may accelerate the growth and metastasis of residual cancer cells, so it is desirable to restrict immunosuppression by surgical stress to a minimum. However, the extent and duration of immunosuppression caused by operations on gastrointestinal cancer, as well as the mechanisms involved, have not been determined.

METHODS

To clarify these points, we investigated immunocyte function and measured the blood levels of hormones, cytokines, and acute phase reactants from before to after operation in 20 patients with stage I gastrointestinal cancer.

RESULTS

In patients exposed to surgical stress, peripheral blood lymphocyte numbers and function were suppressed until at least 2 weeks postoperatively. This immunosuppression was mainly due to a decrease of helper-inducer T cells, cytotoxic T cells, natural killer cells, and interleukin-2 receptor-positive cells, as well as an increase of suppressor T cells. In addition, hypersecretion of cortisol and overproduction of immunosuppressive acidic protein were observed.

CONCLUSIONS

Cellular immunosuppression by surgical stress was mainly due to an increase of lymphocyte subsets that depress cellular immunity coupled with a decrease of the subsets that promote it. Overproduction of cortisol and immunosuppressive acidic protein in response to surgical stress may play an important role in the development of immunosuppression.

Physiological role of endothelin-1 in nonworking muscles during exercise in healthy subjects

Endothelin-1 (ET-1) is a potent vasoconstrictor peptide produced by vascular endothelial cells. However, the role of ET-1 in exercise-induced physiological responses is still to be investigated. The purpose of the present study was to investigate in healthy volunteers whether the ET-1 plasma concentration in nonworking muscles is changed by exercise and to investigate the physiological role of ET-1 during exercise. Bicycle ergometer cardiopulmonary exercise tests were performed in 36 healthy men (mean age, 22.5 years). Blood samples for measuring ET-1 were drawn from the cubital vein during rest and immediately after the exercise test. The ET-1 change ratio was calculated as ET-1 immediately following exercise/ET-1 during the resting state. Cardiac output (CO) was measured during the exercise test by the impedance method. Arterial venous oxygen difference (AVO2D) when CO reached 10L/min or 15L/min was calculated as AVO2D = VO2/CO. Results were as follows: (1) the ET-1 change ratio correlated inversely with exercise time at the anaerobic threshold (r = -0.37, p = 0.03) and peak exercise time (r = -0.35, p = 0.04); (2) the ET-1 change ratio tended toward an inverse correlation with deltaVO2/deltawork rate (r = -0.29, p = 0.09); (3) the ET-1 change ratio correlated positively with AVO2D when CO reached 10L/min (r = 0.42, p = 0.02) and tended toward a positive correlation with AVO2D when CO reached 15 L/min (r = 0.32, p = 0.08). These results indicate that an increase in ET-1 in nonworking muscles may participate in the exercise-induced redistribution of blood flow and in increasing the blood flow to working muscles.

Purulent pericarditis due to group B streptococcus and mycotic aneurysm of the ascending aorta: case report

A 61-year-old female, with a history of uterine and cervical cancer treated with radical hysterectomy and 2 years of postoperative chemotherapy, presented to the emergency department with dyspnea on exertion. Computed tomography of the chest revealed a large pericardial effusion and a sacciform aneurysm of the ascending aorta. The patient subsequently underwent emergency pericardiocentesis with drainage of approximately 330 ml of a bloody and turbid effusion. Cultures from the effusion yielded group B streptococcus. Multiple organ failure and disseminated intravascular coagulation syndrome occurred in the acute phase, but gradually improved with continuous antibiotic therapy. On the 194th hospital day, in situ reconstruction of the ascending aorta was successfully performed using a synthetic graft. Although rarely reported, both purulent bacterial pericarditis and mycotic aneurysm can be life-threatening.

The impact of technology on the resolution of minimally invasive training and credentialing challenges of the 21st century

After the meteoric entry of minimally invasive surgery onto the general surgery scene 9 years ago, it currently stands at a crossroads with regard to the 21st century. Many challenges hamper safe and costeffective deployment of minimally invasive techniques. There must be a stabilization and reduction of complication rates associated with laparoscopic cholecystectomy. Common bile duct injuries are in fact two to three times higher for laparoscopic cholecystectomy than for the open procedure. This matter has been discussed only at local morbidity and mortality conferences or at national meetings. Patients are being injured. The surgical community has failed to police itself and the public knows it. This led in 1992 to New York State health officials setting standards of training and surgeon preparedness for performing laparoscopic cholecystectomy. If surgeons don't handle the problem, the politicians and the lawyers soon will.

Development of a new analytical method for the electrocardiogram using short-time first Fourier transforms

To detect the minute electric potential inside the QRS complex, a new frequency domain method was designed using short-time First Fourier Transforms (SFFT) and high-frequency sampling (oversampling). SFFT improved the frequency resolution by oversampling that was applied to this analysis. The electric potential data of 15,000 points received weighted, running average processing and was subtracted from the original waveform to reduce the low-frequency component. The data in a segment of 160 ms, including QRS, was processed by frequency analysis with the SFFT computation routine. The ECG of healthy individuals was analyzed by this method and its usefulness evaluated. The processing waves of the X-axis, Y-axis, and Z-axis of a representative normal subject were formed into 3 groups of peak electric potential. SFFT enabled the detection of the structure inside the QRS complex without signal averaging, and is considered capable of evaluating the process of excitement inside the QRS complex in the various heart diseases.

Some sulfur-containing metabolites of tri-n-butyltin chloride in male rats

In an attempt to elucidate metabolic destination of TBTO, sulfur-containing metabolites were investigated in the urine. Tri-n-butyltin chloride (TBTC), tri-n-butyltin oxide (TBTO), and their in vitro metabolites in rat liver microsomal enzyme systems, di-n-butyl(3-hydroxybutyl)tin chloride (T3OH), di-n-butyl(3-oxobutyl)tin chloride (T3CO), dibutyltin dichloride (DBTC), and monobutyltin trichloride (MBTC), were intraperitoneally administered to rats. In particular, administration of T3OH and T3CO gave higher amounts of mercapturic acid derivatives, such as N-acetyl-S-(3-oxobutyl)-L-cysteine (3CO-MA) and N-acetyl-S-(3-hydroxybutyl)-L-cysteine (3OH-MA), than TBTC or TBTO. On the other hand, DBTC and MBTC did not yield measurable amounts of 3CO-MA and/or 3OH-MA. The appearance of organotin metabolites in urine indicates that T3OH, T3CO, and hypothesized secondary metabolites, such as n-butyl(3-hydroxybutyl)(3-oxobutyl)tin chloride, n-butyl(3-hydroxybutyl)(4-hydroxybutyl)tin chloride, etc., are subject to the action of glutathione S-transferase to give mercapturic acid derivatives. These sulfur-containing metabolites (3CO-MA and 3OH-MA) were also found in control rat urine.

Effects of exercise training on the recovery of the autonomic nervous system and exercise capacity after acute myocardial infarction

This study investigated the effects of aerobic exercise training on the early phase of the recovery process following acute myocardial infarction (AMI) in terms of the autonomic nervous system, cardiac function and exercise capacity. Twenty-eight patients in the first week after the onset of AMI were assigned randomly to either a training group or a control group. The training group performed aerobic exercise for 2 weeks. Cardiopulmonary exercise testing was performed 3 times during the 3 months after the onset. Heart rate variability, plasma norepinephrine (NE) levels, and cardiac index (CI) during exercise were measured. In the training group, plasma NE level and deltaCI (peak CI-rest CI) were significantly improved from 1 to 3 weeks after the onset, and the high frequency of heart rate variability and peak oxygen uptake were significantly increased up to 3 months after the onset. In the control group, the plasma NE level and the deltaCI during the 1-3 weeks post-AMI, the high frequency of heart rate variability and the peak oxygen uptake showed a tendency to improve up to 3 months after the onset. These results indicate that sympathetic nervous activity improves soon after the onset of AMI, in conjunction with improvement in cardiac function, and that this improvement is not affected by exercise training. In contrast, the recovery of parasympathetic nervous activity requires a longer period, along with the recovery of exercise capacity, which is facilitated by even short-term aerobic exercise training.

[Endobronchial ultrasonography for lung cancer]

We assessed the usefulness of endobronchial ultrasonography in the diagnosis of lung cancer. We performed a needle-puncture experiment on 45 normal tissue specimens to determine the luminar structure of the tracheobronchial wall. In addition, we compared the ultrasonographic determination of tumor invasion in 24 lung cancer patients with the histopathological findings. The cartilaginous portions of the extrapulmonary bronchi and the intrapulmonary bronchi exhibited a five-layered structure. Starting on the lumen side, the first layer (hyperechoic) was a marginal echo, the second (hypoechoic) was the submucosal tissue, the third (hyperechoic) was the marginal echo on the inner side of the bronchial cartilage, the fourth (hypoechoic) was bronchial cartilage, and the fifth (hyperechoic) was the marginal echo on the outer side of the cartilage. In the membranous portions, the first layer (hyperechoic) was a marginal echo, the second (hypoechoic) was smooth muscle, and the third (hyperechoic) corresponded to the adventitia. Comparisons between the ultrasonograms and the histopathological findings in 24 lung cancer patients revealed that depth diagnosis was the same in 23 lesions (95.8%) and different in 1 lesion (4.2%). We describe the usefulness of endobronchial ultrasonography in the diagnosis of peribronchial lymph nodes and peripheral pulmonary lesions.

Use of mobile low-bandwith telemedical techniques for extreme telemedicine applications

BACKGROUND

Telemedicine is traditionally associated with the use of very expensive and bulky telecommunications equipment along with substantial bandwidth requirements (128 kilobytes per second [kbps] or greater). Telementoring is an educational technique that involves real-time guidance of a less experienced physician through a procedure in which he or she has limited experience. This technique has been especially dependent on the aforementioned requirements. Traditionally, telemedicine and telementoring have been restricted to technically sophisticated sites. The telemedicine applications through the existing telecommunication infrastructure has not been possible for underdeveloped parts of the world.

STUDY DESIGN

Telemedicine and telementoring were applied using low-bandwidth mobile telemedicine applications to support a mobile surgery program in rural Ecuador run by the Cinterandes Foundation and headed by Edgar Rodas, MD. A mobile operating room traveled to a remote region of Ecuador. Using a laptop computer equipped with telemedicine software, a videoconferencing system, and a digital camera, surgical patients were evaluated and operative decisions were made over low-bandwidth telephone lines. Similarly, surgeons in the mobile unit in Ecuador were telementored by an experienced surgeon located thousands of miles away at Yale University School of Medicine.

RESULTS

Five preoperative evaluations were conducted from Sucua to Cuenca, Ecuador, with excellent clinical correlation. Additionally, a laparoscopic cholecystectomy was successfully telementored from the department of surgery at Yale University School of Medicine to the mobile surgery unit in Ecuador. The telementored surgery was performed using a telephone line with a baud rate of 12 kbps.

CONCLUSIONS

Mobile, low-bandwidth telemedicine applications used in the proper technical and clinical algorithms can be very effective in supporting remote health care delivery efforts. Advantages of such applications include increased cost-effectiveness by limiting travel, expanding services to patients, and increased patient quality assurance.

Natural course of combined limb and palatal tremor caused by cerebellar-brain stem infarction

After infarction of the left superior cerebellar peduncle and dentate nucleus, a patient developed tremor of the left upper limb beginning on the twelfth day followed by palatal tremor appearing 10 months after infarction. Surface electromyogram revealed a difference in the frequency of the tremor in the upper limb and soft palate. When the palatal tremor appeared, brain magnetic resonance T2-weighted images revealed high signal intensity of the contralateral, right inferior olivary nucleus. Subsequently, when the amplitude of palatal tremor became less severe, the high olivary signal intensity subsided whereas the hypertrophy of the nucleus remained. This patient provides useful information on the pathogenesis of skeletal and palatal tremor with brain stem or cerebellar lesions based on the differences in the onset and frequency of tremors and morphologic changes in the inferior olive.

Specialty-related disparities of readmission in patients with chronic heart failure: the importance of hospital-clinic cooperation

OBJECT

The purpose of this study was to elucidate differences in readmission rates and late outcome in outpatients with chronic heart failure treated in different clinical settings.

PATIENTS AND METHODS

This study included 65 consecutive patients who were admitted to our CCU due to acute heart failure for the first time and discharged from our institution. After their discharge, 31 were cared for by a cardiologist in the outpatient clinic of our institution (group A) and the other 34 were cared for by a general practitioner in a clinic (group B). The various findings during the acute phase and the follow-up period were retrospectively compared between the two groups. In addition, the incidence of unexpected readmission and prolonged outcomes were compared between the two groups.

RESULTS

The patients in group B were older than those in group A, but no other differences were noted in patient characteristics. More patients in group A required more than one hospitalization within 6 months from discharge (group A, 35.5%; group B, 8.9%, p<0.01; follow-up period, 17.1+/-5.9 months). There was no difference in the survival rate between the groups.

CONCLUSION

We concluded that stabilized outpatients should receive comprehensive care from a general practitioner to avoid the need for readmission after discharge.

Chemical species of organotin compounds in sediment at a marina

A bottom sediment collected in a marina was analyzed for organotin species, and >20 organotin compounds including biodegraded ones were confirmed by comparison with the synthesized standards using gas chromatography (GC)/mass spectrometry and a GC/atomic emission detection system. Their structures were also determined in comparison with those in a technical grade of tri-n-butyltin chloride (TBTC). Eleven organotin compounds were found in the technical TBTC. Among them, unexpected organotin compounds, such as di-n-butyl(2-ethylhexyl)tin chloride and di-n-butyloctyltin chloride, were identified, although the levels were low. These compounds were also found in the sediment sample. The relationship between organotin compounds in the technical TBTC and those in marine products was also discussed.

Twenty-nine missense mutations linked with familial Alzheimer's disease alter the processing of presenilin 1

1. Full-length form of human presenilin 1 (PS1) is processed and an N-terminal fragment (28 KD) and C-terminal fragment (19 KD) are generated. To elucidate the possible role of presenilin mutations in Alzheimer's disease (AD), the authors analyze the effects of AD-linked mutations on PS1 processing in cultured cells. 2. Complementary DNAs encoding genes for human PS1 harboring twenty-nine missense mutations linked with familial Alzheimer's disease (FAD) were introduced into PC12 cells. Human PS1 exogenously expressed in the cells was detected by immunoblotting using a monoclonal antibody that recognized the N-terminal region of human PS1. The amounts of full-length form (48 KD) and N-terminal fragment (28 KD) of PS1 was quantified by densitometrical analysis. 3. The ratio of the N-terminal fragment to total PS1 was reduced by twenty-nine mutations. The specific effects on PS1 processing varied according to mutation. 4. These results suggest that AD-linked missense mutations of PS1 are involved in neurodegeneration via inhibition of PS1 processing.

Assessment of usefulness of endobronchial ultrasonography in determination of depth of tracheobronchial tumor invasion

STUDY OBJECTIVE

We assessed the usefulness of endobronchial ultrasonography in the determination of the depth of tumor invasion of the tracheobronchial wall.

METHODS

We performed a needle-puncture experiment on normal tissue of 45 specimens to determine the laminar structure of the tracheobronchial wall. In addition, we compared the ultrasonographic determinations of tumor invasion from 24 lung cancer cases with the histopathologic findings.

RESULTS

The cartilaginous portions of the extrapulmonary bronchi and the intrapulmonary bronchi exhibited a five-layer structure. Starting on the luminal side, the first layer (hyperechoic) was a marginal echo, the second layer (hypoechoic) was the submucosal tissue, the third layer (hyperechoic) was the marginal echo on the inner side of the bronchial cartilage, the fourth layer (hypoechoic) was bronchial cartilage, and the fifth layer (hyperechoic) was the marginal echo on the outer side of the cartilage. In the membranous portions, the first layer (hyperechoic) was a marginal echo, the second layer (hypoechoic) was smooth muscle, and the third layer (hyperechoic) corresponded to the adventitia. Comparisons between the ultrasonograms and the histopathologic findings in 24 lung cancer cases revealed that depth diagnosis was the same in 23 lesions (95.8%) and was different in 1 lesion (4.2%). In the single case in which the findings were different, lymphocytic infiltration that protruded between the cartilage rings was mistakenly interpreted as tumor infiltration.

CONCLUSIONS

This method allows visualization of the laminar structure of the tracheobronchial wall, which is impossible with other diagnostic imaging methods.

Exercise-induced changes in plasma atrial natriuretic peptide and brain natriuretic peptide concentrations in healthy subjects with chronic sleep deprivation

Recent observations have shown that plasma levels of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) correlate with cardiac function or prognosis in heart failure patients. However, relatively little is known about changes in their plasma concentration during commonly occurring physiological states such as fatigue. Therefore, this study was designed to examine the physiological changes of plasma ANP and BNP concentrations using a chronic sleep-deprivation model. Bicycle ergometer cardiopulmonary exercise tests were performed in 10 healthy volunteers (mean age: 22.7 years). Blood samples for measuring ANP and BNP were drawn during the resting state and immediately after each exercise test. Cardiac output (CO) was measured during the exercise test by the impedance method. The study conditions were designed as follows: (A) a day following a period of normal sleep (control state) and (B) a day preceded by 1 month during which sleep lasted <60% of normal (chronic sleep-deprived state). Results were as follows. (1) Peak oxygen uptake and peak CO decreased during the sleep-deprived state compared with the control state. (2) There was no difference between peak heart rates measured during exercise under the 2 conditions. (3) Plasma ANP concentration during exercise increased significantly during the control state, whereas only a tendency toward increase was observed during the sleep-deprived state. (4) Plasma BNP concentration during exercise tended to increase in the control state compared with the resting state, whereas there was no difference in plasma BNP between after exercise and resting state in the sleep-deprived state. These results indicate that changes of ANP or BNP induced by exercise tended to be decreased by chronic sleep deprivation.

Enhancement of amyloid beta 42 secretion by 28 different presenilin 1 mutations of familial Alzheimer's disease

Families bearing mutations in the presenilin 1 (PS1) gene develop early onset familial Alzheimer's disease (FAD). Further, some PS1 mutants enhance secretion of the longer form of amyloid beta protein (Abeta42). We constructed cDNAs encoding human PS1 harboring 28 FAD-linked mutations, and examined the effects of the expressed PS1 mutants on Abeta42 secretion in beta amyloid precursor producing COS-1 cells. All the mutants significantly enhanced the ratio of Abeta42 to total Abeta compared with wild-type PS1. However, the increase in Abeta42 ratio in cells with each PS1 mutation did not correlate with the reported age of onset of FAD caused by that mutation. These results suggest that increased Abeta42 secretion is important for the development of Alzheimer's disease (AD), but may not be the only factor contributing to the onset of AD.

Magnesium dynamics and sympathetic nervous system activity in patients with chronic heart failure

This study was undertaken in patients with heart failure to investigate the relation between plasma norepinephrine (NE) concentration and Mg dynamics. The study subjects comprised 16 patients with chronic heart failure (mean age 64.9+/-10.0 years). Cardiopulmonary exercise testing was performed on all patients, and anaerobic threshold (AT), peak oxygen uptake (peak VO2) and peak exercise time were measured. Resting and peak values of plasma NE concentration and serum and erythrocyte magnesium concentration were also measured. The results were as follows: the serum Mg concentration was increased significantly immediately after exercise (p<0.01), and the erythrocyte Mg concentration showed a tendency to decrease (p<0.1). The resting plasma NE level was inversely correlated with AT (p<0.05, r=-0.57), peak VO2 (p<0.05, r=-0.55) and peak exercise time (p<0.01, r=-0.62). When the plasma NE concentration at rest was analyzed in 2 groups of patients, ie, those with higher than average and those with lower than average concentrations, the resting erythrocyte Mg concentration was significantly lower in the high-NE group (2.2+/-0.3 mg/dl) than in the low-NE group (2.7+/-0.5 mg/dl) (p<0.05). The data indicate that patients with chronic heart failure associated with high NE levels at rest who showed low exercise tolerance have intracellular hypomagnesemia, which may be caused by Mg migration from intracellular to extracellular spaces.

Dynamic changes of QT dispersion as a predictor of myocardial ischemia on exercise testing in patients with angina pectoris

The difference between the maximum and minimum QT intervals on the standard 12-lead ECG (QT dispersion) may be a significant predictor of serious arrhythmias. Dynamic changes in QTd were determined during exercise-induced ischemia in 15 patients with effort angina (> or = 75% coronary stenosis) and 10 normal individuals. Treadmill exercise testing was performed according to Bruce's protocol and the rate-corrected QT dispersion (QTcd) was calculated using Bazett's formula. The resting QTcd before exercise was similar in the angina patients and the controls. After the first stage of exercise, QTcd was significantly increased in the angina patients (p = 0.035), while it remained near baseline in the controls. Five minutes after completing exercise, QTcd was significantly greater in the angina patients than in the controls (p = 0.011). Furthermore, QTcd values after the first stage of exercise were significantly correlated with the maximum ST depression observed on completing exercise in the angina patients (r = 0.714, p = 0.0028). Because QTd may represent the heterogeneity of ventricular repolarization, its significant exercise-induced increase in the angina patients suggests that myocardial ischemia caused repolarization disorders. The significant correlation between QTcd values after the first stage of exercise (before significant ST depression) and the maximum ST depression on completing exercise suggests that an increase in QTcd preceding ischemic ST depression may predict myocardial ischemia. In addition, even daily activities not causing significant ST changes may increase QTcd and the risk of serious arrhythmia in angina patients.