[Determinants of patient satisfaction and intention to continue service utilization: analysis of a survey of outpatients at general hospital]

The patient-perceived quality of hospital ambulatory service and its relationship to patient satisfaction and intention to continue utilization of the service were assessed using a questionnaire which was mailed to 1,695 outpatients of a general hospital in Tokyo (response rate, 77.2%). Patient satisfaction and satisfaction and intention of continuing service utilization were each assessed and both for physicians and for the hospital. The quality of hospital outpatient service was evaluated for 36 items, and 9 patient evaluation scales were extracted by factor analysis: i.e., "treatment results", "physician competence and explanation", "physician warmth and commitment", "reputation of hospital and physician", "services by nurses and non-clerical staff", "services by clerical staff", "medical costs and barriers", "hospital environment" and "accessibility to medical care". These scales, with the exception of "accessibility of medical care", had high internal consistency. Accessibility was then decomposed into 4 independent scales-"waiting time", "outpatient clinic hours", "availability of services when needed" and "transportation convenience". The effects of a total of 23 variables, consisting of 12 patient evaluation scales, sex, age, education, income, clinical departments (4 dummy variables), "frequency of service utilization", "perceived severity of disease" and perceived necessity for medical care intervention" on patient satisfaction and patient intention to continue utilization of services were assessed by multiple regression analysis (forced entry method). The results indicated that patient assessment of "treatment results", "physician competence and explanation", "physician warmth and commitment" and "reputation of hospital and physician are important determinants of patients satisfaction and intention to continue using hospital outpatient service.

Assessment of the effects of occupational and environmental factors on all faster and slower large myelinated nerve fibers: a study of the distribution of nerve conduction velocities

To assess the effects of occupational and environmental factors on all faster and slower large myelinated peripheral nerve fibers, we measured the distribution of nerve conduction velocities (DCV) in men exposed to local vibration, lead, thallium, styrene, mixed solvents, and alcohol as well as in diabetic patients. The results indicated that conduction velocities of faster large myelinated nerve fibers are more sensitive to most toxic chemicals and physical factors than those of the slower fibers. Further studies are needed to investigate which of the DCV and the conventional peripheral nerve conduction velocity is a more sensitive indicator of the subclinical effects of these factors and whether zinc and copper antagonize the effects of lead on the DCV.

Assessment of central, peripheral, and autonomic nervous system functions in vibrating tool operators: neuroelectrophysiological studies

To evaluate the effects of vibrating tool operation (i.e., combined stressors of local vibration, noise, cold climate, and heavy work) on the central, peripheral, and autonomic nervous systems, the short-latency somatosensory and brain stem auditory evoked potentials (SSEP and BAEP), the distribution of sensory median nerve conduction velocities (DCV), conventional median nerve conduction velocities (NCV), and the electrocardiographic R-R interval variability (CVRR) were measured in three groups of male vibrating tool operators and age-matched male healthy adults. Two components of the CVRR reflecting parasympathetic activity (C-CVRSA) and sympathetic activity (C-CVMWSA) were also examined. In the first group of vibrating tool operators (15 chain saw operators), all parameters of DCV (V10-V90 velocities) and sensory and motor nerve conduction velocities of NCV were significantly slowed. All peak latencies of SSEP were significantly prolonged, while no significant differences were found in the interpeak latencies of SSEP. The N9 peak latency of SSEP was significantly related to total working days. In the second group of the operators (12 chain saw and 8 brush saw operators), the I-V interpeak and V peak latencies of BAEP were significantly prolonged in the 12 chain saw operators; the I-V interpeak latency of BAEP was significantly correlated with the working years in the 8 brush saw operators. In the third group of vibrating tool operators, i.e., 13 operators with a history of vibration-induced white finger (VWF group) and 11 operators without VWF (non-VWF group), both the CVRR and C-CVRSA were significantly reduced in the VWF group; only the CVRR was significantly reduced in the non-VWF group. Similarly, the faster velocities of DCV (V70, V80, and V90 velocities) were significantly slowed in both the VWF and non-VWF groups. In conclusion, it is suggested that vibrating tool operation affects the faster sensory and motor nerve fibers, the parasympathetic activity, and the auditory pathway from the acoustic nerve to the brain stem.

[Differences in antitumor effect of various BRMs by intratumoral administration: induction of immunosuppressive acidic protein]

The antitumor effects of biological response modifiers (BRM) in a new experimental mouse model, the "double grafted tumor system", were analysed. BALB/c mice received simultaneous inoculations of Meth-A fibrosarcoma cells on right flank (10(6) cells) and left flank (2 x 10(5) cells) on day 0, and BRMs were injected intratumorally into right tumor on day 3, 4 and 5. The growth of the left-flank tumor was the real target for the evaluation of a given drug after 21 days. PSK (a protein-bound polysaccharide preparation), IL-1 and Cepharanthin, cured not only the right, but also the left, non-treated tumor in a double grafted tumor system. OK-432 (a Streptococcus preparation) and BCG cured the right tumor and inhibited the growth of the left tumor. Lentinan (a polysaccharide preparation) inhibited neither the right nor the left tumor. Immunosuppressive acidic protein (IAP) in serum was increased transiently soon after intradermal injection of PSK, OK-432 and TNF in BALB/c mice. But Lentinan did not induce IAP. IAP in serum was gradually increased after intradermal inoculation of Meth-A tumor in BALB/c mice. At 21 days after tumor inoculation, IAP in serum reached a maximum level (300 micrograms/ml). The serum IAP level of Meth-A-bearing mice as well as that of normal mice increased after the intratumoral injection of PSK. At 21 days after tumor inoculation, IAP in PSK-treated mice returned to normal level. The biochemical differences between PSK-induced IAP (early, inflammatory IAP) and Meth-A-induced IAP (late, tumor-induced IAP) was investigated by crossed immunoaffino electrophoresis (CIAE). Inflammatory IAP was rich in biantennary sugar chain, and tumor-induced IAP was rich in tri-tetraantennary sugar chain.

Pharmacokinetics of diltiazem and its metabolites in dogs after oral administration of a multiparticulate sustained-release preparation

Pharmacokinetics of diltiazem and its six metabolites were compared after oral administration in dogs of a multiparticulate sustained-release diltiazem preparation (HER-SR, QD) and a conventional diltiazem preparation (HER, TID). The plasma concentration of diltiazem, its two active basic metabolites (M1, N-monodesmethyl diltiazem; M2, deacetyl diltiazem), and four acidic metabolites [A1, (+)-(2S,3S)-2-(4-methoxyphenyl)-3-acetoxy-4-oxo-2,3,4,5,-tetrahydro-1,5- benzothiazepin-5-acetic acid; A2, 3-deacetyl-A1; A3, O-demethyl-A1; A4, O-demethyl-3-deacetyl-A1] following several administration routes were determined using high-performance liquid chromatography with UV detector (UV-HPLC). Following the oral administration of HER to dogs, plasma concentrations were in the descending order of A2, diltiazem, M1, and M2. The absolute bioavailability of diltiazem was about 30%. Diltiazem conversion to its metabolites (M1, M2, A2) was 31.0, 2.1, and 14.6%, respectively. Following intraduodenal and mesenteric venous administration of diltiazem, M1 and A2 were produced mainly in the intestine and liver. Oral administration of HER-SR and HER to dogs resulted in almost-identical plasma concentrations of A2, diltiazem, M1, and M2 (descending order). Supported evidence was the effective absorption of diltiazem from all gastrointestinal tract regions and similar formation ratios of diltiazem basic metabolites (M1, M2) from the duodenum, ileum, and colon.

Are faster or slower large myelinated nerve fibers more sensitive to chronic lead exposure? A study of the distribution of conduction velocities

To determine which of the faster and slower large myelinated nerve fibers (alpha fiber group) are more sensitive to chronic lead exposure, the distribution of nerve conduction velocities (DCV) as well as conventional sensory nerve conduction velocity (SCV) were measured once a month for 20 and 11 months in two male lead workers with blood lead concentrations of 70 to 121 and of 63 to 85 micrograms/dl, respectively. Differences in the frequency beyond the "normal" ranges between conduction velocities of faster nerve fibers (V80, V90, or SCV) and those of slower fibers (V10 or V20) were analyzed by the McNemar test. In the two lead workers, the values below the lower normal limits for the V80 and V90 velocities were more frequent than those for the V10 and V20 velocities; similarly, lower values for the SCV were more frequent than those for the V10 and V20 velocities (P < 0.05). It was suggested that faster nerve fibers are more sensitive to chronic lead exposure than slower nerve fibers. These findings agree with our published data on the effects of local vibration, thallium, n-hexane, styrene, mixed organic solvents, alcohol dependency, and diabetes mellitus.

A mouse homolog of the Escherichia coli recA and Saccharomyces cerevisiae RAD51 genes

Analysis of mitotic and meiotic recombination in mammalian cells has been hampered by the complexity of the reactions involved as well as lack of mutants. Furthermore, none of the genes involved in the process has yet been identified. In budding yeast, Saccharomyces cerevisiae, the RAD51 gene is essential along with other genes of the RAD52 epistasis group for mitotic and meiotic recombination and DNA repair. The Rad51 protein is structurally similar to Escherichia coli RecA protein, which is required in homologous recombination and SOS responses in bacteria. Here we report the isolation of a mouse homolog of the yeast RAD51 gene. The amino acid sequence predicted from the gene shows 83% and 55% homology with those of the yeast RAD51 and the E. coli recA product, respectively. The mouse gene complemented a rad51 mutation of S. cerevisiae with sensitivity to methyl-methanesulfonate, which produces double-strand breaks of DNA. This gene is expressed in the thymus, testis, ovary, spleen, and intestine, suggesting that its product is involved in mitotic and meiotic recombination in addition to DNA repair.

Expression of group-II phospholipase A2 in malignant and non-malignant human gastric mucosa

The expression of Group-II phospholipase A2 (M-PLA2) was analysed immunohistochemically in malignant, non-malignant (including atrophic, hyperplastic, pseudopyloric metaplastic and intestinal metaplastic) and normal human gastric mucosae. M-PLA2 was consistently detected in the stem cell lineage, pseudopyloric metaplasia and the generative cells of hyperplastic foveolar epithelium and intestinal metaplasia (IM). In IM, the appearance of M-PLA2 was found to be closely related to the degree of development of the brush borders on columnar cells and was especially prominent at dense brush borders. Paneth cells of IM, particularly their secretory products, were strongly immunoreactive for M-PLA2. In gastric cancer, the expression of M-PLA2 was detected exclusively in cancer cells with a low grade of differentiation, and seemed to be intensified in the invading zone of the tumour. These observations suggest that the expression of M-PLA2 is associated with the proliferative kinetics and regeneration of human gastric mucosa, and may indicate a physiological relationship between its expression and metaplasia of small intestinal type. Moreover, the appearance of M-PLA2 may be related to the invasive ability of gastric cancer.

The effects of walking at the anaerobic threshold level on vertebral bone loss in postmenopausal women

The purpose of this study was to determine the optimal intensity of exercise necessary to prevent the postmenopausal bone loss on the basis of anaerobic threshold (AT). Thirty-three postmenopausal women were randomized to control (group C: n = 12) or two exercise groups (group H and group M). All women performed a treadmill exercise test, and the AT was measured by expired gas analysis. The exercise regimen consisted mainly of walking at a speed that kept the exercise heart rate above the AT (group H: n = 12) or below the AT (group M: n = 9). Exercise was performed for 30 minutes, three times a week for 7 months. The bone mineral density (BMD) of the lumbar vertebrae was measured using dual energy X-ray absorptiometry. The BMD level in group C decreased by 1.7 +/- 2.7%, but there was a significant increase of 1.1 +/- 2.9% in group H. In group M there was a decrease of 1.0 +/- 3.1% which did not differ from group C. In group C, serum osteocalcin and urinary hydroxyproline excretion were significantly increased, but no changes were seen in either of the exercise groups. Urinary calcium significantly decreased in the exercise groups. We conclude that short-term (7 months) exercise with intensity above the AT is safe and effective in preventing postmenopausal bone loss.

Low-dose dobutamine stress test for the evaluation of cardiac function using ultrafast computed tomography

High dose-dobutamine (DOB) has been previously used as a pharmacological stress test to evaluate wall motion abnormalities. As a result, recent stress echocardiography with low-dose DOB has been reported to be valuable for investigating stunned myocardium after thrombolysis. However, echocardiography requires an operator's skill and experience to evaluate wall motion abnormalities which are subjectively determined by the observer. In contrast, ultrafast computed tomography (UFCT) does not necessarily require extreme technical skill and experience. To evaluate the feasibility of stress UFCT with low-dose DOB, we scanned 10 normal subjects along the short-axis by 8-slice-multicine mode. After scanning at rest for baseline, we scanned during the administration of 4 and 8 micrograms/kg/min of DOB, respectively, for 5 min. Ejection fraction, contraction, and thickening were higher during 8 micrograms/kg/min of DOB than during 4 micrograms/kg/min of DOB and baseline, while the above values were higher during 4 micrograms/kg/min of DOB than during baseline (p < 0.01). It was possible to detect changes of cardiac function and wall motion due to low-dose DOB by UFCT. We therefore conclude that UFCT is a reliable modality for evaluating cardiac function and wall motion for low-dose DOB stress test because of its excellent spatial and contrast resolution.

Increased expression of membrane-associated phospholipase A2 shows malignant potential of human breast cancer cells

BACKGROUND

Recently, the authors reported that membrane-associated phospholipase A2 (M-PLA2) was one of the acute phase reactants and increased in serum of patients with various malignant tumors.

METHODS

M-PLA2 concentrations in tissue specimens from 78 breast cancers, 16 benign breast tumors, and 10 normal breast tissues were determined by a specific radioimmunoassay recently developed. Immunohistochemical staining was performed on all specimens by the avidin-biotin-peroxidase method.

RESULTS

Tissue levels of M-PLA2 concentration were significantly higher in breast cancer than in benign breast tumor or normal breast tissue (P < 0.01). Correlation analyses between the tissue concentration of M-PLA2 and clinicopathologic factors showed that tissue M-PLA2 levels were significantly higher in patients with skin or muscle invasion, vessel involvement, and distant metastasis than in those without. In addition, this enzyme concentration was significantly greater in scirrhous carcinoma than in papillotubular or solid-tubular carcinoma. No association was found between M-PLA2 concentration and steroid hormone receptor status. Immunohistochemically, M-PLA2 was preferentially stained in the invading zone of breast cancer tissues, especially in scirrhous carcinoma. Patients with breast cancer with low levels of M-PLA2 showed significantly longer overall survival and disease-free survival compared with those with high levels of this enzyme at the cutoff point of 50 ng/100 mg protein. The combination of estrogen receptor status with M-PLA2 concentration could be a powerful prognostic factor in predicting such survival rates.

CONCLUSIONS

M-PLA2 is closely related to the malignant potential of breast cancers, and the M-PLA2 contents in breast cancer tissues could be a new valuable prognostic factor, other than the hormone receptor, in delineating the status of human breast cancer.

Pharmacokinetic analysis of an oral sustained-release diltiazem preparation using multifraction absorption models

Application of multifraction absorption models to pharmacokinetic analysis of an oral sustained-release diltiazem preparation (HER-SR) was investigated. The plasma diltiazem concentrations after oral administration of the HER-SR preparation were analyzed using both the two-fraction absorption model and the two-step discontinuous absorption model. The two-fraction absorption model was suitable for the pharmacokinetic analysis of the HER-SR preparation, whereas the two-step discontinuous absorption model is often unsuitable for the analysis of sustained-release preparations which disintegrate into fractions with different release characteristics in the gastrointestinal tract. The two-step discontinuous absorption model is usually not applicable to plasma concentration data when the first peak is sharp. MFA-MULTI(V) was shown to be useful for the prediction of the bioavailability in each fraction of HER-SR. It was further demonstrated that a two-fraction absorption model is useful for the comparison of in vitro and in vivo release profiles or evaluating the influence of food on the absorption behavior of HER-SR. In addition, the application of a two-fraction absorption model to population pharmacokinetics of HER-SR was investigated.

Assessment of central, peripheral, and autonomic nervous system functions in lead workers: neuroelectrophysiological studies

To assess the effects of lead on central, peripheral, and autonomic nervous systems, the visual-, short-latency somatosensory-, and brainstem auditory-evoked potentials (VEP, SSEP, and BAEP), event-related potential (P300), distribution of nerve conduction velocities (DCV), and electrocardiographic R-R interval variability (CVRR), together with conventional median and radial nerve conduction velocities (NCV), were measured in the lead workers. The lead workers consisted of 22 gun metal foundry workers occupationally exposed to lead, zinc, and copper. In the lead workers with blood lead concentrations below 65 micrograms/dl, the latencies of the VEP (from the retina to the visual cortex), SSEP (from the brachial plexus to the brainstem), and P300 (which reflects cognitive function) were significantly prolonged when compared with the sex- and age-matched controls. All these latencies and the BAEP latencies (from the cochlear nerve to the brainstem) were significantly correlated with the indicators of lead absorption among these workers. The CVRR (especially, a component of parasympathetic activity) was significantly depressed in the lead workers. The slower (V10) velocity of the DCV, the motor, and sensory NCVs were also significantly slowed. These findings suggest that lead affects not only peripheral nerve but also the central and autonomic nervous functions at a subclinical level; zinc may antagonize the neurotoxic effects of lead.

Assessment of the distribution of nerve conduction velocities in alcoholics

To assess the effects of chronic alcohol ingestion on the faster and slower nerve fibers (alpha fiber group) in the peripheral nervous system, the distribution of nerve conduction velocities (DCV) and conventional maximal motor and sensory nerve conduction velocities (MCV and SCV) in the median nerve were measured in 23 male patients with severe alcoholic dependency (DSM-III-R), aged 30-64 (mean, 50) years, and in 23 age-matched healthy men. The DCV was expressed by the conduction velocities below which 10, 20,..., 80, and 90% of active fibers lie (V10, V20,..., V80, and V90 velocities). The V40 to V90 velocities of the DCV were significantly slower in the alcoholics than in the control subjects; the SCV and MCV in the alcoholics were also significantly slowed. These findings suggest that the faster large myelinated nerve fibers are more sensitive to chronic alcohol ingestion than the slower large myelinated nerve fibers.

Time-course of left atrial performance during coronary artery occlusion followed by reperfusion in anesthetized dogs by densitometric analysis of digital atrioventriculographic images

The left atrial (LA) function during coronary artery occlusion followed by reperfusion using densitometric analysis of digital atrioventriculographic images was evaluated. Eight anesthetized dogs underwent atrioventriculography at baseline, 10 and 60 min after left circumflex coronary artery (LCX) occlusion and 5, 30, 60, and 120 min of reperfusion. Time-density curves were obtained for LA and left ventricle (LV). The ratios of passive atrial video-densitometric change (VC) to total VC (Passive Ratio), and active VC to total VC (Active Ratio) were calculated. Left ventricular ejection fraction (LVEF), peak ejection rate (PER), and peak filling rate (PFR) were derived. Active Ratio, an index of atrial contraction, increased to 144%, and Passive Ratio decreased to 75% of baseline at 60 min of LCX occlusion. Two hours after reperfusion, both Active and Passive Ratios returned to control level. While LVEF reduced to 70%, PER to 67%, LV peak positive dP/dt to 88% of baseline at 60 min after occlusion, and remained depressed at 2 h after reperfusion. However, PFR, LV peak negative dP/dt and LV isovolumic pressure decay rate showed recovery at 2 h after reperfusion. There were significant correlations between PFR and Passive Ratio (r = 0.41), and between Active and Passive Ratios (r = 0.55). Thus, time-course of recovery of LV post-ischemic systolic and diastolic function was different. Return of LA function to control level during 2 h after reperfusion may be depend on recovery of LV diastolic function.

Radial and median nerve conduction velocities in workers exposed to lead, copper, and zinc: a follow-up study for 2 years

To evaluate the interactive effects of lead, zinc, and copper on the peripheral nervous system in man, we measured maximal motor and sensory conduction velocities (MCV and SCV) in the distal radial and median nerves in 19 gun metal foundry workers with asymptomatic increased absorption of these metals twice at a 12-month interval. The workers' initial blood lead (BPb) concentrations ranged from 16 to 64 (mean, 42) micrograms/dl. The principal findings in the present study indicated that (1) radial and median nerve conduction velocities were significantly slowed in the gun metal foundry workers; (2) indicators of lead absorption were inversely related to radial nerve conduction velocities, whereas indicators of copper and zinc absorption were positively correlated with the radial and median nerve conduction velocities; and (3) yearly changes in MCV in the radial nerve and in SCV in the median nerve were positively correlated with the changes in indicators of copper and zinc absorption. These findings suggest that zinc and copper antagonize the subclinical neurologic effects of lead. Also, the radial and median nerve conduction velocities provide important indicators of subclinical lead toxicity.

[A case report of Weber's syndrome associated with supranuclear vertical gaze palsy caused by the ipsilateral thalamomesencephalic lesion]

We report a rare case showing Weber's syndrome associated with supranuclear vertical gaze palsy caused by the ipsilateral lesion of the rostral interstitial nucleus of the medial longitudinal fasciculus (riMLF), which is regarded as the supranuclear control center of vertical gaze. To date, no literature concerning Weber's syndrome associated with the ipsilateral riMLF lesion was documented. The patient was a 53-year-old female, who suddenly developed unconsciousness and left-sided weakness. Neurological findings on admission revealed right third nerve palsy, severe supranuclear vertical gaze palsy, almost complete convergence palsy, left hemiparesis and hyperreflexia with positive Babinski's sign on the left side. There was no sign of pupillary disturbance or no abnormality of the horizontal movements of the left eye. The vestibulo-ocular reflex of the left eye was preserved. There was no sensory disturbance. Cranial MRI had the advantages in demonstrating unilateral ischemic lesions at the cerebral peduncle and the thalamomesencephalic junction involving the unilateral riMLF on the right side. Recent reports have demonstrated that supranuclear vertical gaze palsy is caused by the unilateral riMLF lesion. We confirm that the unilateral riMLF lesion causes supranuclear vertical gaze palsy in our case and that cranial MRI has the advantages in demonstrating the specific lesion.

Appearance of a regenerating (reg) gene protein in pancreatic islets of remission BB/Wor//Tky rats

Remission of diabetes, i.e. significant amelioration from absolute insulin-dependency, has been sometimes observed in diabetic BB/Wor//Tky rats which were treated with insulin. In remission BB/Wor//Tky rats, plasma glucose levels improved to near normal level and insulin content was also preserved as much as that between diabetic and non-diabetic rats. In this process, we hypothesized that autoimmune insulitis was suppressed and remaining islet B-cells was restored from severe destruction by recovering in number and/or function. While, recently, a novel regenerating (reg) gene, identified in the regenerating pancreatic islets of surgical models, is reported to be related to the replication of pancreatic B-cells in vitro. Based on these findings, we histologically investigated whether the reg protein could be actually expressed or not in the islets from remission BB/Wor//Tky rats. As expected, reg protein was observed in the islets from remission BB/Wor//Tky rats mainly in accordance with pancreatic B-cells. Thus, the present findings suggested that the regeneration of pancreatic B-cells represented by the expression of reg protein might be, at least in part, relevant to remission induced by insulin therapy in spontaneously occurring Type 1 diabetes in BB/Wor//Tky rats.

Morphological properties of human thyroid tumor cells in collagen gel culture and metastatic or invasive ability

Using normal human thyroid cells and tumor cells, the reconstruction of various diseased cells in collagen gel as well as the relationship between the morphology of colonies in collagen-embedded culture and the biological behavior (benignity, malignancy, metastasis, and invasion) of the original tumors were studied. In collagen gel culture, normal thyroid cells reorganized follicle-like constructions, and follicular adenoma cells showed in vivo-like constructions. However, two different types of colonies were observed in cultures of cells from papillary carcinomas. One was the branching type with many outgrowths projecting to three dimensions and the other was the spherical type without any outgrowths. These spherical colonies were observed in all cases of papillary carcinoma, but varied from one case to another. Metastasis and invasion were detected during pathological examination in cases with a high ratio of spherical colonies. Our results indicate that cells from highly metastatic and invasive thyroid cancer form spherical colonies in the collagen gel culture, and that this collagen culture is a useful method for studying the heterogeneity of tumor cells as well as the metastasis and invasive ability of tumor cells in vitro.

The possible involvement of protein phosphatase 1 in thrombin-induced Ca2+ influx of human platelets

Protein phosphatase 1 is considered to be involved in thrombin-induced platelet activation (Murata et al., Biochem Int 26:327-334, 1992). To clarify the mechanism, we examined the effects of protein phosphatase 1 and 2A inhibitors (calyculin A, tautomycin, okadaic acid) on Ca2+ influx. In the presence of 1 mM Ca2+, thrombin- (0.1 U/ml) induced platelet aggregation and ATP release were inhibited by calyculin A, while this inhibitory effect was abolished in the absence of Ca2+ (EGTA 1 mM). Furthermore, thrombin-induced Mn2+ influx but not intracellular Ca2+ mobilization was inhibited by calyculin A in a dose-related manner. Calyculin A also blocked the ongoing Ca2+ influx when added 3 min after thrombin stimulation. Similar inhibitory effects were observed with okadaic acid and tautomycin in the same potency sequence as the reported one for protein phosphatase 1 (calyculin A > tautomycin > okadaic acid). These results suggest that the anti-platelet effects of phosphatase inhibitors are due to the inhibition of Ca2+ influx and that protein phosphatase 1 plays a key role in the regulation of receptor operated Ca2+ channel of human platelets.

Cholera toxin inhibits lethal hit stage of natural killer cell-mediated cytotoxicity

Cytolytic process which was affected by cholera toxin (CT) resulting in the loss of natural killer (NK) cell activity was analyzed. Conjugate formation assay, membrane phospholipid methylation assay and serine esterase (granzyme A) release assay were used to determine the stage of the CT-induced inhibition of NK cell-mediated cytotoxicity. A human NK cell line YT cell-mediated cytotoxicity was completely abolished by CT pretreatment or addition of CT to the assay system. The conjugate formation assay revealed that the binding between YT cells and target cells was not affected by CT. The defined triggering stage which is coupled with membrane phospholipid methylation was not affected by CT treatment, either. On the other hand, the lethal hit stage which is represented by serine esterase (SE) release was completely inhibited by CT treatment of YT cells. Therefore, CT inhibits the stage after binding and triggering--i.e., lethal hit stage of NK cell-mediated cytotoxicity. The results also suggest that there exists a CT-sensitive negative cytotoxic signal transduction pathway as well as usual positive signal transduction pathway and these pathways might cross talk each other in the NK cell cytotoxic process.

[Proliferating cell nuclear antigen (PCNA) on human diseased thyroid cells]

Surgical materials obtained from 5 normal human thyroids and 19 diseased tissues (4 with Grave's disease, 4 adenomatous goiters, 3 follicular adenomas, 2 papillary carcinomas, 4 follicular carcinomas and 2 undifferentiated carcinomas) were investigated immunohistochemically using the avidin-biotin-peroxidase complex technique with anti-proliferating cell nuclear antigen (PCNA) antibody and epidermal growth factor receptor (EGFR) antibody. The results of this study suggested the following: (1) Labeling indexes of PCNA positive cell nuclei were shown in high grade malignant cases accompanied by capsular invasion and lymph node metastasis, in undifferentiated carcinoma cells, and in proliferative lesions of benign diseases. These results suggest that PCNA is indicative of proliferative ability in thyroid diseases. (2) On thyroid tumors, EGFR regions with strong positive staining showed many PCNA positive cell nuclei. EGF appears to have a significant association with proliferative ability in thyroid diseases.

Human early placental trophoblasts produce an epidermal growth factor-like substance in synergy with thyroid hormone

Previous studies have shown that human trophoblast is the site of epidermal growth factor (EGF) localization, reception and action and that thyroid hormone exerts similar effects on trophoblasts endocrine function as observed with EGF. Thus, the present study was designed to examine local production of an EGF-like substance in synergy with thyroid hormone by early placenta. Explants of normal early (7-8 weeks) placentas were cultured in a serum-free condition in the presence or absence of L-triiodothyronine (T3), with or without cycloheximide for 4 days. The conditioned media were dialyzed, lyophilized, acidified and chromatographed over a Sephadex G-75 column equilibrated with 1 mol/l acetic acid. EGF was measured by a specific RIA for human EGF. Fractionation of the serum-free conditioned media resulted in the elution of immunoreactive EGF with an apparent molecular weight of 9,000 which is larger than [125I] human EGF. The addition of T3 (10(-8) mol/l) resulted in increased secretion of immunoreactive EGF by placental explants. By contrast, the addition of cycloheximide (5 x 10(-5) mol/l) dramatically reduced the secretion of immunoreactive EGF. The similarity of the immunoreactive EGF material to authentic human EGF was supported by parallel displacement in human EGF-RIA. These results suggest that human early placental trophoblast is capable of producing an EGF-like substance and that thyroid hormone enhances the local production of the EGF-like substance. This suggests that an autocrine/paracrine control system, wherein EGF serves as the signal in regulating placental growth and function in synergy with thyroid hormone, exists in human early placenta.

Topology and subcellular localization of FtsH protein in Escherichia coli

FtsH protein in Escherichia coli is an essential protein of 70.7 kDa (644 amino acid residues) with a putative ATP-binding sequence. Western blots (immunoblots) of proteins from fractionated cell extracts and immunoelectron microscopy of the FtsH-overproducing strain showed exclusive localization of the FtsH protein in the cytoplasmic membrane. Most of the FtsH-specific labeling with gold particles was observed in the cytoplasmic membrane and the adjacent cytoplasm; much less was observed in the outer membrane and in the bulk cytoplasm. Genetic analysis by TnphoA insertions into ftsH revealed that the 25- to 95-amino-acid region, which is flanked by two hydrophobic stretchs, protrudes into the periplasmic space. From these results, we concluded that FtsH protein is an integral cytoplasmic membrane protein spanning the membrane twice and that it has a large cytoplasmic carboxy-terminal part with a putative ATP-binding domain. The average number of FtsH molecules per cell was estimated to be approximately 400.