Evaluation of current sterility tests for human live viral vaccines

Current sterility tests for human viral vaccines were evaluated. A total of 43 lots of bulk suspension of live viral vaccines (measles, mumps, rubella and oral poliomyelitis) produced by six manufacturers in Japan were evaluated for bacteriostatic and mycoplasmastatic activities. Some of them showed fairly high bacteriostatic and mycoplasmastatic activities, due to antibiotics added during vaccine production. It was concluded that the current sterility test for mycoplasmas is not reliable to detect viable mycoplasmas in live viral vaccines.

Hemorrhage and abnormal veins in acoustic neurinoma: MR findings

We reviewed the MR imaging findings of 57 acoustic neurinomas which were verified at surgery or diagnosed on the basis of neuroradiological and neurootological data. Two uncommon MR findings of acoustic neurinoma were found. First, hypointense areas were observed on T2-weighted images in five of the 12 tumors larger than 25 mm in diameter. These hypointense areas represented hemosiderin deposition secondary to occult intratumoral hemorrhage. Second, curvilinear or round signal voids were noted at the periphery of 11 large or medium-sized tumors, and these corresponded to "abnormal veins" seen on angiographic studies.

Participation of gap-junctional cell communication on the adaptive response in human cells induced by low dose of X-rays

To investigate the radioadaptive response of normal cells to low-dose radiation, we irradiated human embryonic (HE) cells and HeLa cells with low-dose X-rays and examined the changes in sensitivity to subsequent high-dose X-irradiation using the trypan blue dye-exclusion test. When HE cells were irradiated by 200 cGy, the growth ratio of the living cells 5 days after the irradiation decreased to 37% of that of the cells which received no X-irradiation. When the cells received a conditioning irradiation of 10-20 cGy 4 h before the irradiation of 200 cGy, the relative growth ratios increased significantly to 45-53%, and a peak was reached at a conditioning dose of 13 cGy to the cells. This conditioning effect was not observed in LeLa cells. When the HE cells were suspended in a Ca2+ ion-free medium or TPA added to the medium while receiving the conditioning irradiation of 13 cGy, the effect of the conditioning dose was not observed. This indicates that normal cells show an adaptive response to low-dose radiation and become more radioresistant. These results suggest that gap junctional intercellular communication may play a role in radioadaptive responses in human cells.

A human friendly reporting and database system for brain PET analysis

We have developed a human friendly reporting and database system for clinical brain PET (Positron Emission Tomography) scans, which enables statistical data analysis on qualitative information obtained from image interpretation. Our system consists of a Brain PET Data (Input) Tool and Report Writing Tool. In the Brain PET Data Tool, findings and interpretations are input by selecting menu icons in a window panel instead of writing a free text. This method of input enables on-line data entry into and update of the database by means of pre-defined consistent words, which facilitates statistical data analysis. The Report Writing Tool generates a one page report of natural English sentences semi-automatically by using the above input information and the patient information obtained from our PET center's main database. It also has a keyword selection function from the report text so that we can save a set of keywords on the database for further analysis. By means of this system, we can store the data related to patient information and visual interpretation of the PET examination while writing clinical reports in daily work. The database files in our system can be accessed by means of commercially available databases. We have used the 4th Dimension database that runs on a Macintosh computer and analyzed 95 cases of 18F-FDG brain PET studies. The results showed high specificity of parietal hypometabolism for Alzheimer's patients.

[Normal CBF values by the ARG method using IMP SPECT: comparison with a conventional microsphere model method]

N-isopropyl-p[123I]iodoamphetamine (IMP) has been used as a flow tracer for SPECT, and measurement of cerebral blood flow (CBF) using IMP has been performed by conventional microsphere model method (MS method). Recently, the ARG method for measuring CBF by using IMP with one SPECT scan and one point blood sampling has been developed. This method was based on two-compartment model. In the present study, normal CBF values were measured in ten male healthy subjects (mean age +/- S.D.: 29.8 +/- 6.01, age range: 23-41) by the ARG and the MS methods. The mean CBF values (+/- S.D.) for the ARG method in which the Vd value was assumed to be 50 ml/ml were 41.7 +/- 9.4, 31.1 +/- 5.0, 40.7 +/- 9.7, 41.5 +/- 10.0, 38.2 +/- 9.2, 39.0 +/- 9.4, 41.9 +/- 10.6, 38.7 +/- 8.0 and 30.0 +/- 7.7 ml/100 ml/min in the cerebellum, pons, thalamus, basal ganglia, frontal, temporal, parietal, occipital lobe cortex and centrum semiovale, respectively. The mean CBF values for the MS method were 46.8 +/- 8.4, 37.5 +/- 5.6, 45.8 +/- 8.6, 46.5 +/- 8.9, 43.7 +/- 8.3, 44.4 +/- 8.7, 46.8 +/- 9.3, 44.3 +/- 7.3 and 36.3 +/- 8.1 ml/100 ml/min, respectively. The mean CBF values in the cerebral cortex region for the ARG method were lower than those previously reported by PET. This would be caused by low first-pass extraction fraction of IMP compared with oxygen-15 labeled water. The mean CBF values for the MS method were higher than those for the ARG method against previous studies. As reasons for this, errors in estimation of the SPECT brain counts at 8 min in the MS method were considered.

[Follow-up study of vestibular neuronitis]

A follow-up study of 26 patients with vestibular neuronitis is reported. The disease is characterized by an acute attack of severe vertigo with complete loss of unilateral caloric response. The following results were obtained: 1) The average period of spontaneous nystagmus was 136 days and the standard error was 39 days. 2) No correlation could be found between age and the period of spontaneous nystagmus. 3) Six patients showed direction reversal in their spontaneous nystagmus (recovery nystagmus), and their outcome was good. 4) On the most recent caloric test, 42% of the patients had bilateral normal responses, 27% displayed partial improvement on the affected side, and no reaction was observed in 31% of patients. We suggest that three types of clinical courses may occur in vestibular neuronitis: i) complete recovery of the function of the affected vestibular nerve, ii) partial recovery of vestibular function, and iii) no recovery of the affected vestibular nerve, but central nervous system compensates for the vestibular imbalance.

The clinical utility of visual evaluation of scintigraphic perfusion patterns for Alzheimer's disease using I-123 IMP SPECT

The authors examined the role of SPECT perfusion pattern in the diagnosis of Alzheimer's disease (AD) using I-123 IMP. They studied 93 patients who had memory and cognitive disorders, including 42 patients with a diagnosis of probable AD, classifying SPECT images into determined perfusion patterns. The probability of AD was 54% with bilateral temporal and/or parietal defects, 69% with bilateral temporoparietal defects with additional defects, 17% with no defects, and 11% with frontal defects only. The sensitivity of bilateral temporoparietal perfusion defects for AD was 95.2%, whereas the specificity was 56.9%. In the absence of bilateral temporal and/or parietal defects on visual evaluation of SPECT, the diagnosis of AD was unlikely, although it is not pathognomonic for AD, because this sign would be seen in various neuropsychiatric diseases causing memory and cognitive impairments. Visual evaluation of SPECT is of value in the diagnosis of AD among patients with dementia.

Functional neuroanatomy of visual object naming: a PET study

BACKGROUND

The ability to name objects depends partly on visual perception. We used positron emission tomography (PET) to measure activity-related changes in regional cerebral blood flow (r-CBF) in order to identify regions of the brain activated during visual object naming.

METHODS

Four right-handed volunteers were recruited. Following an intravenous injection of 15O-labeled water, r-CBF was measured during visual object naming, counting numbers, and resting. PET and MRI images were coregistered, the size of the brain was proportionally adjusted in each axis to Talairach's and Tournoux's atlas, and the comparison of stimulated versus resting blood flow images revealed activated brain regions.

RESULTS

In the subtraction of resting from naming, activation was observed in the bilateral primary visual cortex, bilateral fusiform gyrus, left lingual gyrus, bilateral inferotemporal cortex, bilateral inferior frontal gyrus, bilateral precentral gyrus, anterior cingulate gyrus, left parietal operculum, and left putamen. In the subtraction of counting from naming, most of the those areas were activated, but no significant activity was observed in the left lingual gyrus, left parietal operculum, or bilateral precentral gyrus (motor cortex). The areas activated with the paradigm included those dedicated to visual perception (primary and associate visual cortex), visual recognition (inferior temporal cortex), and phonological output (Broca's area).

CONCLUSION

Our results indicated that the major neural network from occipital lobe to frontal cortex, which is mainly involved in the ventral visual pathway, demonstrated activation in these tasks. Result of this study will serve as base line data for analyzing the findings in patients with impaired visual perception.

MR findings indicative of hemosiderin in giant-cell tumor of bone: frequency, cause, and diagnostic significance

OBJECTIVE

We studied the frequency, cause, and diagnostic significance of MR findings indicative of large amounts of hemosiderin in giant-cell tumor of bone.

MATERIALS AND METHODS

The clinical, MR, and histologic findings in 16 patients with giant-cell tumors of bone were reviewed. Eight tumors occurred in uncommon locations or in patients who were not in the usual age range; the other eight were more typical. Areas of decreased MR signal intensity considered to be caused by hemosiderin were identified. The number and distribution of RBCs within the tumor were studied histologically, and the presence of hemosiderin was determined on histologic sections made with iron stains.

RESULTS

In 10 cases in which MR images showed areas of low signal intensity, large amounts of hemosiderin were noted histologically. The low-signal-intensity areas were nodular, zonal, whorled, or diffuse and occupied at least one fifth of the tumor volume. On histologic examination, many erythrocytes were in direct contact with the tumor cells, and the hemosiderin was seen in both mononuclear and multinuclear tumor cells.

CONCLUSION

Hemosiderin is commonly seen on MR images of giant-cell tumors of bone (63%) and is probably related to the extravasated erythrocytes in the tumor and the phagocytic function of the tumor cells. This MR finding supports the diagnosis, even in giant-cell tumors in uncommon locations or in patients who are not in the typical age range.

The telemetric monitoring of heart rate, locomotor activity, and body temperature in mice and voles (Microtus arvalis) during ambient temperature changes

We have studied the physiological and behavioural responses in small rodents to ambient alterations. For this purpose, voles and mice were exposed to relatively low (12 degrees C) and high (35 degrees C) ambient temperatures, and heart rate (HR), locomotor activity (LA) and body temperature (BT) were recorded using telemetry system. The control HR (at 24 degrees C) of voles was lower than that of mice. The 'heat exposure' decreased HR to 85.0 +/- 3.3% in voles, and to 78.0 +/- 3.2% in mice compared with the mean HR of the same time in the control day. The 'cold exposure' increased the HR to 131.9 +/- 8.8% in voles, and 119 +/- 10.9% in mice. The decreasing rate of HR in heat exposure was smaller in voles than mice, and in cold exposure the increased rate was larger in voles than mice. Cold exposure decreased BT in both species; 96.1 +/- 0.5% in voles and 93.7 +/- 1.0% in mice. The LA was not changed significantly by heat exposure in either species, but was partially increased by cold exposure. These results demonstrate that telemetry was helpful for qualitative and quantitative behavioural studies in small rodents, and confirmed that the physiological and behavioural responses to ambient temperature changes differed between these animals.

Relationship between core temperature and skin blood flux in lower limbs during prolonged arm exercise in persons with spinal cord injury

The purposes of the present study were to examine the response of the skin blood flux (SBF) in the paralyzed lower limbs of persons with spinal cord injury (PSCI) and to clarify the relationship between the SBF and core temperature during prolonged arm exercise. Eight male PSCI with lesions from T6 to L5 and six male control subjects (CS) participated in this study. The subjects rested for 60 min and then performed arm-cranking exercise at 20 W for 30 min at 25 degrees C. The tympanic membrane temperature (Tty) and SBF in the anterior thigh (SBFT) and in the posterior calf (SBFC) were continuously measured throughout the experiment. The SBFC did not change in either PSCI or CS during the experiment. The SBFT in four PSCI with high lesions (T6 to T12), remained unchanged during exercise. The SBFT in the other four PSCI with low lesions (T12 to L5, delta SBFT+) began to elevate markedly when the Tty exceeded a threshold temperature of 36.69 degrees C. The pattern of increase of SBFT in delta SBFT+ was similar to that in CS, although onset of the increase in SBFT was delayed and the peak of SBFT during exercise was significantly lower in comparison with the CS. We consider that these differences between the delta SBFT+ and CS were largely attributable to the lower Tty in the former group, which took a prolonged time to reach the threshold of 36.69 degrees C.

Immunohistochemical study of hepatic angiomyolipoma

An immunohistochemical study was performed on nine hepatic angiomyolipomas (AML) found in eight patients. Histologically, the tumors were fundamentally composed of the three heterogeneous tissue components of blood vessels, smooth muscle cells (SMC), and fat cells, although the proportions and distributions were quite variable from tumor to tumor and from area to area in the same tumor. Additionally, cellular pleomorphism and atypia with occasional bizarre giant cells were found in the SMC component. This histologic feature might lead to a mistaken diagnosis of malignant neoplasm, and pathologists should therefore be aware of the broad histologic spectrum of hepatic AML. However, the immunostaining patterns were basically the same in all nine tumors. All tumor components were negative for epithelial membrane antigen (EMA) and for cytokeratin. The spindle-shaped SMC component of the tumor was occasionally positive for vimentin, desmin and alpha-smooth muscle actin, whereas epithelioid SMC were negative for all three. Both the epithelioid and spindle-shaped SMC were occasionally positive for S-100 and neuron-specific enolase. All types of SMC in the tumor, whether spindle, epithelioid, intermediate or pleomorphic SMC, were strongly positive for HMB-45, a melanoma-specific monoclonal antibody. Fat cells were occasionally positive for S-100. Endothelial cells were positive for factor VIII-associated antigen. Among hepatic tumors HMB-45 reactivity is, so far as we know, found exclusively in the SMC of AML, and the HMB-45 reactivity of a hepatic tumor is thus clearly an important piece of information in the diagnosis of AML.

Magnetic resonance imaging of neurogenic tumors of the thoracic inlet: determination of the parent nerve

To investigate the value of magnetic resonance imaging (MRI) in determining the parent nerves of neurogenic tumors in the thoracic inlet, analysis of MR images was performed in nine patients with surgically resected neurogenic tumors in the thoracic inlet (two neurofibromas and one schwannoma of the vagus nerve, three schwannomas of the brachial plexus, and two schwannomas and one ganglioneuroma of the sympathetic nerves). These MR images were compared with surgical and pathologic findings. The multidirectional capability and excellent tissue contrast of MRI facilitated recognition of the location, shape, and extent of the tumors. MRI, which permitted an easy understanding of the spatial relation between the tumors and the subclavian vessels, scalenus muscles, and brachial plexus, was useful in determining the nerves of origin. Two neurofibromas, four of six schwannomas, and one ganglioneuroma were recognized to extend along the axes of the parent nerves on MR images. MRI is useful in determining the parent nerve of neurogenic tumors in the thoracic inlet and is helpful in planning surgical treatment of these tumors.

Reconstitution of SCID mouse with tonsillar cells from patients with IgA nephropathy

IgA nephropathy (IgAN) is characterized by a predominant IgA deposition to the renal mesangium. Immunological abnormalities are closely related to the occurrence and progression of IgAN. Many reports have indicated that tonsillectomy favours the clinical course of IgAN. To understand the role of tonsil glands in the occurrence and progression of IgAN, we injected tonsillar lymphoid cells from patients with IgAN into severe combined immuno-deficient mice (SCID). Tonsillar glands were obtained surgically from 3 patients with IgAN (experimental group) and from 7 patients with chronic tonsillitis without any manifestation of renal diseases (control group). Tonsils were homogenized and resultant cells cryopreserved. On the day of injection, cells were thawed and passed through Ficoll-Paque gradients to obtain mononuclear cells. Fifty million cells were injected intraperitoneally into the SCID mice. After 8 weeks, transferred cells successfully reconstituted SCID, as shown by the fact that human immunoglobulins were detected in the sera of both groups. Renal histopathological examination revealed there was no IgA deposition to the mesangial area in either group. These results indicate that tonsillar mononuclear cells alone may not directly relate to the occurrence of IgAN.

Significance of metabolic and blood pressure factors in relation to microangiopathy and macroangiopathy in patients with non-insulin-dependent diabetes mellitus

We are actively seeking methods to prevent and to limit the progression of angiopathy in patients with non-insulin-dependent diabetes mellitus (NIDDM). In the present study, we conducted a clinical and epidemiological survey to clarify the clinical factors responsible for the development and progression of diabetic microangiopathy (MI) and macroangiopathy (MA). A total of 107 patients (58 female and 49 male) were randomly selected from 145 NIDDM patients. Twenty-four patient variables were selected for analysis. We identified PWV, UAI, RETINOP, MCV-T, SCV-S, MCV-P, SBP, and DBP as responsible factors and carried out stepwise multiple regression analyses. The following explanatory variables were found to be significant: age > SCV-S (P < 0.0001) for the criterion variable PWV, BUN > HbA1c > MCV-P > HT-drug > HDL-C (P < 0.0001) for log(e) UAI, DM-thera > SBP (P < 0.0001) for RETINOP, MCV-P (P < 0.0001) for MCV-T, IRI > SBP > MCV-P > S-CR (P < 0.0002) for SCV-S, MCV-T > SCV-S > DM-thera (P < 0.0001) for MCV-P, DBP > HT-drug > BUN > MCV-P (P < 0.0001) for SBP, and SBP > PWV > sex (P < 0.0001) for DBP. In summary, responsible factors for MI and MA in NIDDM had metabolic and blood pressure factors in common. Moreover, MI was a responsible factor for MA, which becomes a responsible factor for MI because it is a responsible factor for blood pressure factors. Thus, all the responsible factors for MA represented by MI and PWV had metabolic and blood pressure factors in common. The results of this study suggest that metabolic and blood pressure factors must be controlled to prevent and to limit the progression of diabetic MI and MA in NIDDM patients.

Relationship between cardiac autonomic neuropathy and diabetic microangiopathies and macroangiopathy in patients with non-insulin-dependent diabetes mellitus

The relationship between cardiac autonomic neuropathy and diabetic microangiopathies and macroangiopathy was investigated in 103 patients with non-insulin-dependent diabetes mellitus. Cardiac autonomic nerve function was assessed by determining the uptake of [123I]metaiodobenzyl-guanidine into the myocardium. Cardioparasympathetic nerve function was assessed by comparing electrocardiographically the expiratory and inspiratory respiratory rate (RR) interval ratios, during a period of deep breathing, and the coefficients of variation of the RR intervals. Nerve conduction velocity measurements were used to assess diabetic somatic neuropathy, and measurement of pulse-wave velocity provided an indication of the extent of aortic sclerosis. The only correlations between the parameters of cardiac autonomic neuropathy and parameters of diabetic microangiopathies and macroangiopathy were between the expiratory to inspiratory RR interval ratio and both the conduction velocity of the tibial nerve and pulse-wave velocity, and between the heart to lung ratio (cardiac autonomic nerve function) and nephropathy. These correlations may have occurred by chance; alternatively they may indicate a difference in the onset mechanisms of cardiac parasympathetic and sympathetic neuropathies in diabetics.

Diversity of the neuropathies in patients with non-insulin-dependent diabetes mellitus

The relationships between cardiac autonomic neuropathies, diabetic somatic neuropathy, metabolic parameters, general parameters (such as age and duration of illness) and diabetic microangiopathy and macroangiopathy were investigated in 103 patients with non-insulin-dependent diabetes mellitus (NIDDM). Spearman's correlation coefficients were calculated for the comparisons of all the parameters of the neuropathies with all the other parameters. Variables were selected using a stepwise procedure and multiple regression analysis was carried out using these variables. The results of the regression analysis show that diabetic neuropathy is correlated with vascular parameters including blood pressure and pulse-wave velocity, as well as with parameters of sugar and lipid metabolism. The results confirm the diversity of the clinical characteristics of the neuropathies in patients with NIDDM and confirm that these neuropathies do not always occur in parallel.

Use of an alpha-glucosidase inhibitor to synchronize sugar absorption with delayed insulin secretion in a patient with non-insulin-dependent diabetes mellitus

The case of a 67-year-old women with non-insulin-dependent diabetes mellitus is described. Diabetes was first diagnosed when the woman was aged 55; a diet of 1440 kcal daily was recommended and 500 mg tolbutamide daily was prescribed. Hypoglycaemia was improved for a while but the blood-sugar concentration gradually increased until a tolbutamide dose of 2000 mg/day was needed. The patient eventually came to an out-patient clinic for diabetes control due to continuous hyperglycaemia. Her diabetes proved difficult to control, probably due, in part, to excessive eating and lack of exercise, despite appropriate education and glibenclamide treatment. After 15 months, an alpha-glycosidase inhibitor, at a dosage of 0.75 mg/day, was added to the treatment with glibenclamide at 7.5 mg/day and the glycosylated haemoglobin level was reduced to normal levels within 2 months. After a further 6 months the glibenclamide dose was reduced to 3.75 mg/day with no ill effects during the subsequent 4 weeks, up to the present day.

[A case of malignant oncocytoma of the parotid gland]

A case of malignant oncocytoma of the left parotid gland occurring in a 57-year-old man presenting with a painless lump is reported. The tumor was round, firm, mobile, well defined, and located in the left preauricular area. There was no evidence of facial weakness. At operation the left parotid gland was exposed to reveal a tumor arising from the superficial lobe, but involving the facial nerve. Superficial lobectomy was performed followed by reanastomosis using the great auricular nerve for the sacrificed facial nerve. Subsequently, the tumor recurred 13-months after the primary excision. The patient underwent radical neck dissection and was given supplementary radiation therapy. Because DNA-FCM of the tumor showed diploid-type with a large G2/M peak, we regarded radiation therapy as being potentially effective. Follow-up examinations performed two years later revealed no evidence of regional or distant metastases. The histologic examination of the original and the recurrent lesion showed large atypical cells, with abundant eosinophilic granular cytoplasm, which were often pleomorphic and highly-mitotic. Under ultrastructural examination, the cytoplasm contained numerous mitochondria of various shapes and sizes. These pathological findings were consisted with malignant oncocytoma.

Efficient production of the C-terminal domain of secretory leukoprotease inhibitor as a thrombin-cleavable fusion protein in Escherichia coli

We have developed a high-level production system for the C-terminal domain of secretory leukoprotease inhibitor (SLPI) to investigate its pharmacological activities. A gene for the C-terminal domain of SLPI, (Asn55-Ala 107)SLPI, was constructed from chemically synthesized deoxyoligonucleotides. It was fused to a gene for the N-terminal portion of human growth hormone via a DNA sequence encoding Leu-Val-Pro-Arg, which can be cleaved by thrombin. The fused gene was expressed in Escherichia coli under the control of a trp promoter, and the fusion protein was obtained as an inclusion body. After sulfonation of the cysteine residues, the sulfonated fusion protein was cleaved at the desired site by thrombin. Sulfonated (Asn55-Ala107) SLPI was refolded in Tris buffer containing reduced and oxidized glutathione. The resulting (Asn55-Ala107) SLPI was purified by cation-exchange chromatography and reverse-phase high performance liquid chromatography. The final yield was 50 mg/I culture. (Asn55-Ala107) SLPI was as active against elastase as, but had less trypsin inhibitory activity than, native SLPI. This system is suitable for the large-scale production of the C-terminal domain of SLPI, which is an elastase-specific inhibitor.

Epidural dumbbell-shaped chordoma mimicking a neurinoma

The authors present a case of cervical chordoma which manifested in a 5-year-old boy as a dumbbell-shaped epidural tumor without bone destruction. Both CT and MRI demonstrated tumor features suggesting this diagnosis, which was confirmed by histology.

Enhanced liver injury in acatalasemic mice following exposure to carbon tetrachloride

The hypothetical involvement of hydrogen peroxide (H2O2) in carbon tetrachloride (CCl4)-induced acute liver injury and the potential preventive effect of catalase on hepatotoxicity have been studied in acatalasemic (C3H/AnLCsbC2b) mice and compared with normal (C3H/AnLCsaCsa) mice. A single intraperitoneal injection of CCl4 (20% in olive oil/g body weight) caused increases in serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels in both mouse groups, but the extents of increases did not show significant differences between the two mouse groups until 12 h. The variation in increases of serum AST and ALT levels in acatalasemic and normal mice turned to be distinctly different from 12 h. At 18 h (peak point for ALT) and 24 h (peak point for AST), the serum enzyme levels in acatalasemic mice were nearly two-fold higher than those in normal ones, the difference being statistically significant (p < 0.01). The liver malondialdehyde (MDA) level in acatalasemic mice was also higher than that in normals at 18 h (p < 0.05). The extent of the centrilobular necrosis was histologically more severe in acatalasemic mice. The catalase activity in livers of acatalasemic mice was one-third to one-fifth those of normal mice (p < 0.05) before and after treatment. The decreased catalase activity in acatalasemic mice might increase tissue or cellular levels of H2O2 during the later phase of the acute liver injury. From these findings, we conclude that H2O2 breakdown in liver would account for the difference in the later stages of the acute liver damage between the two groups of mice, and catalase is important in inhibiting hepatotoxicity of CCl4 in the later stage.

Involvement of neurohumoral factors in the pressor mechanism of NG-nitro-L-arginine

The mechanism of the NG-nitro-L-arginine (L-NNA)-induced pressor response was examined in pentobarbital-anesthetized dogs. The pressor effect of L-NNA (50 mg/kg, i.v.) was significantly and equally diminished by pretreatment with either hexamethonium (25 mg/kg, i.v.) or phentolamine (5 mg/kg, i.v.). The intracisternal administration of L-NNA (1 mg/kg), which did not cause changes in cardiovascular parameters when administered systemically, produced a significant pressor response and tachycardia. Furthermore, significant suppression of L-NNA-induced pressor responses was observed after treatment of dogs with captopril (5 mg/kg, i.v.) or a non-peptide angiotensin II receptor antagonist, losartan (10 mg/kg, i.v.), or bilateral occlusion of renal veins. The inhibitory effects of hexamethonium and losartan were additive. These results suggest that, in addition to vasoconstriction due to the inhibition of endothelial nitric oxide production, increased activity of the sympathetic nervous and renin-angiotensin systems contributes significantly to the development of pressor responses produced by the intravenous injection of L-NNA in anesthetized dogs.

Hardness of denture reline materials polymerized with different techniques

Two kinds of hard type self-cured denture reline materials were polymerized using three different techniques: (1) on a surface of glass plate, (2) under water, (3) under water with some hardening agent. Hardness of specimens were measured longitudinally during three weeks periods of storage in water at 37 degrees C. Results of our study indicated that the specimen cured with the special hardening agent showed the higher hardness than those cured only in water. Most of the hardness changes took place during first three days of the experiment period.