[Exertional hypoxemia evaluated by pulse oximetry in patients with interstitial lung diseases]

The pattern of change in arterial oxyhemoglobin saturation (SpO2) measured by pulse oximetry (PO) during exercise, including daily activities, was studied in 23 patients with interstitial lung disease (ILD), 19 of whom had idiopathic pulmonary fibrosis, 3 collagen vascular disease, and 1 BOOP. Hypoxemia, as detected by PO appeared without dyspnea at the beginning of exertion or at a mild workload. Exercise usually induced significant changes in the same fashion first in heart rate, then in SpO2, and then in dyspnea, but stair climbing had a different pattern. Workload at the lactate threshold (LT) and symptom-limited maximal exercise (SL) in a bicyclergometer incremental exercise test correlated well with distance walked in a 10-minute walking test (10-eMD) (p < 0.01). Similarly, the degree in desaturation in each exercise test was closely correlated (p < 0.01). Exertional hypoxemia was more prominent in patients with ILD than in those with chronic pulmonary emphysema. Nevertheless, dyspne changed less per change in SpO2 in ILD patients. We conclude that prolonged monitoring of SpO2 by PO will disclose the presence of exertional desaturation in ILD patients.

The growth hormone-releasing hormone-cyclic adenosine-3',5'-monophosphate signal pathway in somatotropes is practically intact during aging

To elucidate the mechanisms of the impaired pituitary response to growth hormone-releasing hormone (GHRH) in aged animals on a cellular basis, a reverse hemolytic plaque assay was performed on dispersed pituitary cells from young (8-month-old) and old (26-month-old) male F344 rats. The proportion of growth hormone (GH)-plaque forming somatotropes, i.e., actually functioning somatotropes, was reduced in old rats to 50-60% of that in young rats under both unstimulated and GHRH-stimulated conditions. The response of dispersed cells to GHRH, however, seemed to remain unchanged with age when expressed as a percent increase of plaque-forming cells from the basal value. The mean diameter of plaques, which reflects the average amount of GH secreted from a single cell, was not smaller in old rats under either the unstimulated or stimulated conditions. There was also no difference between the two age groups in the frequency distribution of the plaque size of functioning somatotropes. The stimulation by forskolin, a compound that directly activates membrane-bound adenylate cyclase and consequently provokes the cyclic adenosine-3',5'-monophosphate (cAMP) pathway for GH secretion in somatotropes, produced almost the same results as those by GHRH stimulation. It was concluded, therefore, that the impaired response of the pituitary gland to GHRH could be due mostly to a reduction in the density of functioning somatotropes rather than to impairments in steps of the GHRH-cAMP signal pathway in somatotropes .

Long-term infusion of kallikrein attenuates renal injury in Dahl salt-sensitive rats

We investigated whether long-term infusion of kallikrein would attenuate renal injury in salt-induced hypertension in Dahl salt-sensitive rats. A subdepressor dose of purified rat urinary kallikrein (700 ng/d IV) was infused by osmotic minipump for 4 weeks in male Dahl salt-sensitive rats fed a high salt (2% NaCl) diet. This dose did not affect the time-dependent elevation of blood pressure; however, urinary protein excretion was significantly decreased, and glomerular filtration rate was increased. These beneficial effects were reflected morphologically by an attenuation of glomerulosclerotic lesions and tubular injury seen in the hypertensive Dahl salt-sensitive rats. Kallikrein infusion increased urinary excretion of bradykinin and stimulated excretion of cyclic GMP, suggesting that the kallikrein-kinin-prostaglandin and nitric oxide axes were enhanced by rat urinary kallikrein infusion. The alterations induced by kallikrein infusion were potentiated by the concomitant administration of the angiotensin-converting enzyme inhibitor alacepril. These studies indicated that long-term replacement with rat tissue kallikrein attenuates renal injury in hypertensive Dahl salt-sensitive rats.

Cost effectiveness of radiofrequency catheter ablation versus medical treatment for paroxysmal supraventricular tachycardia in Japan

This study evaluated the cost of performing radiofrequency catheter ablation in Japanese patients with paroxysmal supraventricular tachycardia refractory to antiarrhythmic drug therapy in comparison with the cost of continuing pharmacologic treatment. Twenty patients (mean age 44 +/- 14 years) underwent successful ablation: 15 patients with Wolff-Parkinson-White syndrome and five with atrioventricular nodal reentrant tachycardia. The mean duration of symptoms was 77 +/- 60 months. The patients had been treated with 2.6 +/- 1.7 antiarrhythmic drugs before undergoing ablation. Charges derived from hospital bills were compared with the outpatient charges for the year before ablation. The mean hospital stay for the ablation procedure was 4.3 +/- 0.5 days. The mean total charge for ablation was 982,806 yen +/- 103,195, and 5.7 +/- 0.7 times the outpatient charges in the previous year. The majority of radical cure charges were the costs of the electrode catheters used in the ablation procedure. All patients had a successful outcome and required no additional antiarrhythmic drug therapy. If medical treatment were continued without ablation, the mean total life-expectancy charges were estimated at 7,064,726 yen +/- 3,116,621, 41.0 +/- 19.2 times the outpatient charges. The total life charges of medical treatment were significantly more than the total ablation charges (p < 0.001). This study suggests that radiofrequency catheter ablation is of clinical benefit in treating paroxysmal supraventricular tachycardia, and markedly reduces the cost of definitive therapy. This strategy appears to be more economical than pharmacologic treatment.

Vulnerability to oxygen radicals is more important than impaired repair in hepatocytic deoxyribonucleic acid damage in aging

BACKGROUND

Many previous reports have shown an age-related increase in DNA damage in hepatocytes. This change is thought to result from alterations in DNA repair capacity, DNA vulnerability to oxygen radicals, or both.

EXPERIMENTAL DESIGN

Single-cell gel electrophoresis (comet assay), which measures single-strand breaks/alkali-labile sites in the DNA of individual cells, was used to compare DNA repair capacity and vulnerability to damage in hepatocytes prepared from the livers of young (6 to 11 months) and old (26 to 29 months) male Fischer 344 rats. DNA damage was induced in a portion of the cells by exposure to 882 mM hydrogen peroxide. Comet images (migration distance of DNA (MDD) were assessed at the basal level (before exposure) and at 0, 1, 2, and 4 hours' incubation after exposure.

RESULTS

The mean basal values of MDD (MV-MDD) and the proportion of hepatocytes with highly damaged DNA (P-HDD) were found to be significantly higher in advanced age. When cells were challenged with hydrogen peroxide, MV-MDD did not differ significantly between the two groups. Interestingly, however, cellular distribution analysis revealed a larger subpopulation of cells with high DNA vulnerability to hydrogen peroxide in rats of advanced age. Furthermore, both MV-MDD and P-HDD were restored almost to basal level at 2 hours incubation after exposure in cells from young rats, while neither recovered even at 4 hours incubation in cells from old rats. This contrast suggests that there is a significant age-related decline in DNA repair capacity.

CONCLUSIONS

The low repair capacity in advanced age depends on a subpopulation of cells showing high DNA vulnerability to hydrogen peroxide. Therefore, an increase in the proportion of hepatocytes exhibiting high vulnerability to oxygen radicals is more important than the deterioration in DNA repair capacity in the age-related increase in DNA damage.

Analysis of flow in a two-dimensional collapsible channel using universal "tube" law

This paper presents an extension of the previous analyses on the collapsible tube-flow problem using a simplified model based on a two-dimensional channel conveying a one-dimensional flow. The main objective of the paper is to exploit the static and dynamic behavior of the model, by comparing with available experimental data and examining the accuracy of calculated results obtained for different numerical resolutions. The main revision from the previous analyses is the incorporation of a universal "tube" law that is valid for a wide range of positive and negative transmural pressure. Most of the numerical results agree qualitatively with the experimental observations. Self-excited high-frequency oscillation with very small amplitude of the membrane wall is however, predicted to occur in a flow range where the slope of the pressure drop curve is positive. It is seen that the high-frequency oscillation is associated with the motion of the separation point of the flow.

Cognitive event-related potentials and brain magnetic resonance imaging in HTLV-1 associated myelopathy (HAM)

Auditory and visual cognitive event-related potentials (ERPs) were investigated in 14 patients with HTLV-1 associated myelopathy (HAM) and in 36 normal controls. In the HAM patients, the latencies of P300 and N200 by the auditory tone method were significantly delayed, and N100 by the auditory click method was significantly delayed in latency. No abnormal ERP components were observed with visual methods. While these auditory abnormal ERPs were present in the HAM patients, there was no evidence of visual abnormal ERPs. Abnormal lesions on the white matter were evident at magnetic resonance imaging (MRI) in 6 (75%) of 8 patients. There was no correlation between MRI lesions and the abnormalities of ERPs, but there was a significant correlation between bifrontal index on MRI and P300 amplitudes at Cz and Pz sites by auditory tone method. In one patient, atrophy of bilateral parietal lobes was seen on MRI and P300 latencies delayed using various methods. Therefore, the possibility that electrophysiological cognitive impairment in patients with HAM is related to brain atrophy rather than to white matter lesions requires attention.

Localization of the mRNA for bone matrix proteins during fracture healing as determined by in situ hybridization

The expression of the mRNAs for osteonectin (ON), osteopontin (OPN), osteocalcin (OC), and matrix Gla protein (MGP) was studied by in situ hybridization during the healing process of an experimental fracture in adult rat femora. At day 1 postoperatively, ON mRNA was detected in the proliferating periosteum. At day 3, ON, OPN, and OC mRNAs were detected in woven bone. From day 5, MGP and ON mRNAs were detected in the immature chondrocytes. From day 7, ON, OPN, and OC mRNAs were detected in the osteoblastic cells in newly formed endosteal trabecular bone. OPN mRNA was also detected in some of the osteocytes in trabecular bone. From day 14, OPN and MGP mRNAs were detected in newly formed periosteal hypertrophic chondrocytes, and the ON, OPN, and OC mRNAs were detected in osteoblastic cells in newly formed periosteal trabecular bone. Although the cell types that expressed each mRNA in fractured bones were similar to those in embryonic bones, the time course of these mRNA expression in fractured bones was different from that in embryonic bones. We considered that this system is useful to investigate the phenotypic change in osteogenic and chondrogenic lineage cells that appears during fracture healing at the molecular level.

["State of the art" of adjuvant chemo-endocrine therapy for breast cancer in Japan]

Breast cancer is a solid tumor moderately responsive to chemotherapy and/or endocrine therapy. Based upon meta-analysis covering 233 prospective randomized clinical trials, a consensus about adjuvant chemo and endocrine therapy has been reached according to prognostic factors, including nodal status, tumor size, estrogen receptor and histological grade. The preventive effect of tamoxifen against recurrence has been also proven in Japanese ACETBC (adjuvant chemoendocrine therapy for breast cancer) trials and KEIO BR1 trial. Several other prospective randomized trials have been run in Japan, and the results will be obtained within several years. The features of breast cancer in Japan are low incidence and good prognosis. In these circumstances, the accrual of a vast number of patients and multi-institutional collaboration are essential. The issues under investigation include best chemotherapy dosage and duration, identification of risk factors and the role of preoperative chemotherapy.

Auditory and colored visual P300 in patients with sequelae of subacute myelo-optico-neuropathy

To study the cognitive function in 13 patients with sequelae of subacute myelo-optico-neuropathy (SMON), event-related potentials (ERPs) were elicited with tones, clicks, and colored visual stimuli in different tasks. P300 latency was delayed, and P300 amplitude reduced or absent in 5 patients (38%), although neuropsychological assessment for dementia did not differ between patients and 21 age-matched normal controls. P300 and N200 latencies with the tone/tone auditory stimuli and N200 latency with the visual stimuli were significantly delayed, but the latencies of early components (N100 and P200) were not delayed. These findings suggest that SMON patients may have cognitive dysfunction to a slight degree.

Structure of cell wall mannan of Candida kefyr IFO 0586

We conducted a structural analysis of the antigenic cell wall mannoprotein (mannan) isolated from Candida kefyr (formerly Candida pseudotropicalis) IFO 0586. The result of two-dimensional homonuclear Hartmann-Hahn analysis of this mannan indicates that the molecule is constructed from alpha-1,2- and alpha-1,6-linked mannopyranose residues. Upon alkali treatment (beta-elimination reaction), this mannan released two alpha-1,2-linked mannooligosaccharides, biose and triose. The structure of the alkali-stable mannan (outer chain) moiety was investigated by acetolysis. The structures of the resultant oligosaccharides, biose and triose, from the outer chain moiety were found to be the same as those of the alkali-released ones. Further, the treatment of the parent mannan with an Arthrobacter GJM-1 exo-alpha-mannosidase gave a linear mannan consisting solely of alpha-1,6-linked mannopyranose residues. These results indicate that the mannan forms the long backbone of the alpha-1,6 linkage, with a large number of short alpha-1,2-linked oligomannosyl side chains forming a comblike structure. Moreover, we investigated the serological properties of this mannan by performing an inhibition assay of a slide agglutination reaction with mannooligosaccharides and polyclonal factor sera (Candida Check; Iatron). The result indicates that the factor 1 serum preferentially recognizes the alpha-1,2-linked oligomannosyl side chains in this mannan. On the other hand, the fact that the mannan does not contain an antigenic determinant(s) corresponding to factor 8 suggests that the epitope(s) of this factor resides in other molecules on the cell surface of this strain.

Candidiasis caused by Candida glabrata in the forestomachs of a calf

A female Japanese black calf suffering from diarrhoea was treated with six different antibiotics for 9 days. The diarrhoea worsened and the calf was killed when 17 days old. At necropsy, the mucosal surface of the forestomachs showed diffuse haemorrhagic necrosis and pseudomembrane formation. Candida glabrata infection was diagnosed histologically, immunohistochemically, and by isolation and examination of the yeast. The intensive antibiotic treatment was considered to have been a predisposing or exacerbating factor. This is the first report of C. glabrata infection of the bovine forestomachs.

Effects of midazolam and diazepam as premedication on heart rate variability in surgical patients

We have examined the effects of midazolam 0.06 mg kg-1 i.m. and diazepam 0.2 mg kg-1 orally as premedication on the spectral components of heart rate (HR) variability in 24 elderly patients aged 65-87 yr and 24 young patients aged 18-35 yr undergoing elective surgery. The low-frequency/high-frequency (LF/HF) ratio of HR variability increased after arrival in the operating room in elderly patients who received no premedication, but not in young patients. In elderly patients who received midazolam or diazepam, the LF/HF ratio did not increase. However, diazepam increased the low-frequency component and the total power of HR variability in both young and elderly patients. We conclude that cardiac sympathetic nerve activity increased after arrival in the operating room in the elderly, that midazolam or diazepam reduced this increase and that diazepam caused an increase in the total power of HR variability that has not been observed for other agents.

Distribution of acetylcholinesterase activity in the rat embryonic heart with reference to HNK-1 immunoreactivity in the conduction tissue

Acetylcholinesterase (AChE) activity was topographically investigated in the presumptive cardiac conduction tissue regions visualized by HNK-1 immunoreactivity in rat embryos, and AChE-positive cells were examined with the electron microscope. On embryonic day (ED) 14.5, when HNK-1 was most intensely visualized, AChE activity could not be detected enzyme-histochemically in the conduction tissue regions, except in the ventricular trabeculae and part of the AV node. On ED 16.5, however, the AChE activity was clearly demonstrated in some parts of the developing conduction tissue. One exception was the AV node region, where an AChE-positive area was in close proximity to an area showing HNK-1 immunoreactivity but did not overlap. Furthermore, AChE activity was demonstrated predominantly in the ventricular trabeculae, including cardiac myocytes, but was rather weak in the atrium. With the electron microscope, AChE reaction products were observed predominantly intracellularly in both developing conduction tissue cells and developing ordinary myocytes, and no reactivity was found in neuronal components. From ED 18.5 until birth, both AChE activity and HNK-1 immunoreactivity faded away in the conduction tissue. Thus, transient AChE activity in the embryonic heart seems to be different from the developing adult form and may be related to a morphogenetic function in embryonic tissues, as proposed by other authors.

Duration of dietary restriction: an important determinant for the incidence and age of onset of leukemia in male F344 rats

The effect of duration and age of initiation of dietary restriction (DR) on the spontaneous occurrence of leukemia was studied in male F344 rats. Four nutritional paradigms were employed: Group 1, ad libitum fed; Group 2, dietary restricted starting at 6 weeks of age; Group 3, dietary restricted from 6 weeks to 6 months of age; Group 4, dietary restricted starting at 6 months of age. The relative incidence (relative onset rate) of leukemia was highest in the rats of Groups 1 and 3 and lowest in the rats of Group 2. The age of onset was earliest in Group 1 followed by Groups 3, 4, and 2 in that order. The progression (duration from onset to death) did not differ significantly between the groups. These results indicate that the duration of DR correlates with the incidence and age of onset of leukemia but not with its progression. The age of initiation of DR is not as important a determinant as the duration of DR in regard to incidence and age of onset. The incidence and the age of onset of leukemia appear to relate to the total cumulative energy intake of the rat (i.e., age multiplied by mean daily energy intake).

Effects of DX-9065a, an orally active, newly synthesized and specific inhibitor of factor Xa, against experimental disseminated intravascular coagulation in rats

We investigated the protective effects of DX-9065a, an orally active, newly synthesized and specific inhibitor of factor Xa, against two kinds of experimental disseminated intravascular coagulation (DIC) in rats. Endotoxin-induced experimental DIC was induced by a 4-h sustained infusion of endotoxin at a dose of 100 mg/kg. Thromboplastin-induced experimental DIC was induced by a bolus injection of thromboplastin at a dose of 150 mg/kg. The rats were orally administered DX-9065a at 10, 30 or 100 mg/kg 30 min before endotoxin or thromboplastin injection. In both DIC models, DX-9065a showed a protective effect against DIC, at all doses and in all parameters, including fibrin/fibrinogen degradation products (FDP), fibrinogen level, prothrombin time, activated partial thromboplastin time, platelet count and the number of renal glomeruli with fibrin thrombi. When DX-9065a was orally administrated at 100 mg/kg without endotoxin or thromboplastin, no significant changes were seen in hemostatic parameters except PT and APTT, and no fibrin thrombi or abnormal bleeding were seen in renal specimens. These findings suggest that the new oral anti-Xa drug, DX-9065a, has an effect in reducing the severity of DIC. However, further dose-finding and safety studies of this drug have still to be assessed.

[Influence of bone marrow fat on the determination of bone mineral content by QCT]

Single-energy quantitative CT (SEQCT) is thought to be suitable for long-term observation of changes in bone mineral content in individual patients. However, in patients with osteoporosis, an increase in bone marrow fat cannot be ignored. The relationship between bone marrow fat and bone mineral density (BMD) at different tube voltages of 80 kV and 120 kV was investigated using a set of solution phantoms that we devised, and was also studied in healthy volunteers. On the basis of the results obtained using the solution phantoms, the influence of bone marrow fat accounted for a decrease of 8.9 mg/cm3 in BMD value at 80 kV and of 10.8 mg/cm3 at 120 kV in the presence of 10 vol% fat. These findings suggested that the influence of fat was less at a lower tube voltage. The formulas used to estimate the true bone mineral and fat contents from the BMD values at low and high tube voltages were derived by eliminating the influence of beam hardening. Using these formulas, we studied healthy volunteers, and found that the difference between the true BMD value and the BMD value calibrated for beam hardening averaged 17.8 mg/cm3 at 80 kV and 22.6 mg/cm3 at 120 kV. Moreover, the estimated concentration of bone marrow fat in the volunteers averaged 25.0 vol%. In conclusion, because SEQCT performed at a low tube voltage is less influenced by bone marrow fat, it should be selected for assessment of the clinical response to therapy and for studying sequential changes. However, in patients with a low bone mineral content indicated by SEQCT, it would be worthwhile trying to estimate both true mineral and fat contents in bone using the formulas obtained in this study in order to differentiate decrease in bone mineral from interference by bone marrow fat.

Mechanistic analysis of renal protection by angiotensin converting enzyme inhibitor in Dahl salt-sensitive rats

OBJECTIVE

To investigate whether and how renin-angiotensin inhibition attenuates renal injury seen in salt-induced hypertension in Dahl salt-sensitive (Dahl-S) rats.

METHODS

Dahl-S rats fed a high-salt (4% sodium chloride) diet for 6 weeks were treated with the angiotensin converting enzyme (ACE) inhibitor alacepril or the angiotensin receptor antagonist losartan for 4 weeks. Functional and morphological alterations in the kidney were investigated.

RESULTS

Alacepril decreased systolic blood pressure (SBP). This SBP reduction was associated with the attenuation of cardiac and aortic wall hypertrophy and that of proteinuria and urinary N-acetyl-beta-D-glucosaminidase excretion. Kidney injuries, e.g. glomerular, arterial and tubular damage, were improved with alacepril treatment. Losartan decreased SBP to the same extent as alacepril, but neither renal function nor morphological structure was improved as was the case with alacepril. The response of the renal eicosanoid system to alacepril was inadequate, but cyclic GMP excretion, an indicator of nitric oxide formation, was significantly enhanced and lipid peroxidation in the kidney was decreased.

CONCLUSIONS

The beneficial effects of ACE inhibition on the renal injury in Dahl-S rats outrange those induced by the receptor antagonism. This might be due to multiple factors including an increased vasodepressor eicosanoid system, enhanced nitric oxide formation and possible inhibition of oxygen radical generation in the injured renal tissues.

Inhibitory effect of fatty acids on glucose and insulin uptake in the perfused rat hindquarter

To elucidate the effects of fatty acids on the uptake of glucose and insulin in the muscle, the effects of oleic and palmitic acids on the uptake of glucose and insulin were investigated in perfused hind-quarters of rats. In the absence of insulin, glucose uptake in the hindquarter was slightly, but not significantly, decreased by the addition of oleic and palmitic acids. In the presence of 100 or 500 microU/ml insulin, glucose uptake in the hindquarter (243 +/- 58 or 282 +/- 65 mumol/30 min) was significantly decreased by the addition of 1000 microM oleic acid and 500 microM palmitic acid (175 +/- 50 or 207 +/- 47 mumol/30 min). The decrease in insulin uptake rate, although not significant at 500 microU/ml insulin, is of similar magnitude to the decrease in glucose uptake. In the presence of 1000 microU/ml insulin, glucose and insulin uptake was not significantly altered by the addition of fatty acids. These results indicate that fatty acids directly inhibit the muscular glucose uptake via the decrease in muscular insulin uptake at a physiological concentration of insulin.