A novel membrane glycoprotein involved in ascidian hemocyte aggregation and phagocytosis

Invertebrate hemocytes undergo several cellular defense reactions. To clarify the molecular mechanisms for cellular recognition between hemocytes and also between hemocytes and foreign materials, we established hybridoma clones producing monoclonal antibodies that inhibit hemocyte aggregation (i.e. a cellular reaction between hemocytes) in the solitary ascidian, Halocynthia roretzi. The antibody, A74, also inhibited phagocytosis of foreign materials by H. roretzi hemocytes. Immunocytochemistry of H. roretzi hemocytes using A74 antibody revealed the localization of the A74 antigen on the surface of hemocytes. The A74 antigen, which is referred to as A74 protein, was purified from a hemocyte membrane preparation by three chromatographies on phenyl-Sepharose, A74 antibody-immobilized Sepharose and Mono Q. The A74 protein was a glycoprotein with a molecular mass of 160 kDa; N-glycosidase or neuraminidase treatment resulted in a reduction of its molecular mass. The N-terminal amino acid sequence of A74 protein showed little similarity to other known proteins. Thus, the A74 protein is a novel membrane protein that plays an important role in ascidian cellular defense reactions.

[A clinical study of gastrointestinal flora in patients with, or without MRSA colonization in the upper-respiratory tract after introduction of preventive measures of hospital infection]

In early 1980's methicillin-resistant Staphylococcus aureus (MRSA) was reported as a major pathogenic organism of geriatric hospital infection in Japan. At the same time in the A geriatric hospital MRSA infection was prevalent. To decrease nosocomial infections some active preventive measures against hospital infection were taken since Oct. 1991. After introduction of preventive measures of hospital infection in geriatric ward (190 beds) nosocomial bacteremia and pneumonia were markedly decreased in comparison to the episode number before introduction of prevention. However several patients with MRSA colonization were observed every month. The aim of this clinical study was to clear how frequent MRSA was isolated from the gastric juice and stool. Any MRSA was not observed in 63 cultured stool, but just one MRSA was isolated in patients with MRSA colonization. On the other hand gram-negative organisms, which were E. coli, P. aeruginosa, P. mirabilis etc., were frequently observed in cultured stool. In conclusion, we considered frequency of MRSA colonization in gastrointestinal space was not so high but rather very low.

Sustained activation of blood coagulation in patients with cerebral thrombosis

Recent progress in the measurements of the hemostatic markers enables us to assess the detailed profiles of hemostatic activation in various diseases. To evaluate the degree of hemostatic system activation in patients with cerebral thrombosis, detailed coagulation studies were performed in 28 patients with acute-phase cerebral thrombosis and in 36 with chronic-phase cerebral thrombosis, together with 6 with chronic-phase cerebral hemorrhage and 37 age-matched healthy volunteers. In both acute-phase and chronic-phase cerebral thrombosis, plasma levels of thrombin-antithrombin III complex, plasmin-alpha 2-plasmin inhibitor complex and D-dimer were significantly higher, and antithrombin III and protein C were significantly lower than those in the normal group. Plasma fibrinogen concentration was significantly higher in chronic-phase cerebral thrombosis than that in chronic-phase cerebral hemorrhage. No significant difference was found in these variables between acute-phase and chronic-phase cerebral thrombosis. In addition, there was no difference in these parameters between chronic phase cerebral hemorrhage and normal subjects. These findings indicate that a sustained activation of coagulation and fibrinolysis is present in cerebral thrombosis, and it might contribute to the pathogenesis of cerebral thrombosis.

Immunophenotypes of Reed-Sternberg cells and their variants: a study of 68 cases of Hodgkin's disease

Utilizing a panel of monoclonal and polyclonal antibodies, routine paraffin sections in 68 cases of Hodgkin's disease were examined for the presence of immunoreactivity in Reed-Sternberg (R-S) and related cells by the avidin-biotin-peroxidase complex (ABC) technique. In 14 cases of lymphocyte-predominant Hodgkin's disease (LPHD), R-S cells and the polyploid lymphocytic and histiocytic (L & H) variants of R-S cells were immunoreactive for L26 and alpha 1-antitrypsin (alpha 1-AT) in 9 (64%) and 6 (43%), respectively, whereas the remaining antibodies were negative or rarely positive against L & H variants of R-S cells. R-S cells in 24 cases of mixed cellularity Hodgkin's disease (MCHD) were positive with alpha 1-AT in 63% of cases, positive with LN3 in 71% of cases and positive for BerH2 in 92% of cases. The lacunar cell type of R-S cells in 19 cases of nodular sclerosing Hodgkin's disease (NSHD) were reactive for alpha 1-AT in all cases, BerH2 in 18 cases (95%), and LN3 in 17 cases (89%). Pleomorphic variant of R-S cells in 11 cases of lymphocyte depleted Hodgkin's disease (LDHD) showed reactivity with alpha 1-AT in 9 cases (82%), BerH2 in 6 cases (55%), and LN3 in 9 cases (82%). The incidence of L26 in R-S cells was higher in LPHD than in other three subtypes, whereas the immunohistochemical finding of alpha 1-AT had reverse relevance to the result of L26. The incidence of BerH2 in MCHD and NSHD was higher than that of this antibody in the whole of Hodgkin's disease. R-S cells in NSHD and LDHD were highly positive to LN3, and detection rate of these two types was higher than that in the whole of Hodgkin's disease. No cases showed immunoreactivity with anti-T-cell antibodies (CD3, UCHL1 and DFT1), a marker for natural killer cell (Leu7), and a marker for interdigitating reticulum cell (S-100 protein). These results suggest that correlation between predominant staining pattern and R-S cells and variants thereof in each histological subtype of Hodgkin's disease are as follows: LPHD shows L26+, alpha 1-AT-, BerH2-; MCHD and NSHD show L26-, alpha 1-AT+, BerH2+; and LDHD shows L26-, alpha 1-AT+, BerH2+ or L26+, alpha 1-AT+, BerH2-.

[A case of multiple cerebral aneurysm which showed rapid growth caused by left atrial myxoma]

A 24-year-old woman was admitted complaining of right hemiparesis and episodes of syncope. Computed tomography demonstrated a low density area in the left putaminal region. Intravenous digital subtraction angiography (IVDSA) showed two aneurysms in the distal segment of the right middle cerebral artery. Cerebral emboli from a cardiac source was suspected, and cardioechography was performed. Myxoma was located in the left atrium. The patient was transferred to a cardio surgical unit, and the myxoma was successfully removed. After removal by operation of the cardiac tumor, follow-up third IVDSA was performed. One aneurysm of the distal segment of the right middle cerebral artery had grown larger. On the other hand, the other aneurysm had disappeared. Clipping of the enlarged aneurysm was performed. After the clipping operation of the enlarged aneurysm, a follow-up 4th IVDSA was performed. A new aneurysm of the proximal segment of the left cerebral artery was observed. A follow-up 5th IVDSA was performed, revealing that the new aneurysm was enlarging. No operation was performed, because the aneurysm was the fusiform type. At present, the patient is complaining of slight right hemiparesis and has returned to her job. Here we reported a case of cerebral aneurysm caused by left atrial myxoma.

Expression of kinA and accumulation of sigma H at the onset of sporulation in Bacillus subtilis

Induction of the Bacillus subtilis kinA gene, which codes for a major kinase of the phosphorelay pathway, required the spo0H gene, coding for the sigma H protein, but not the genes spo0A, spo0B, and spo0F at the onset of sporulation. Also, the levels of sigma H in spo0A, spo0B, and spo0F mutants were increased at the onset of sporulation, though induction of spo0H transcription in all of these mutants was appreciably inhibited. In addition, kinA expression was almost completely eliminated in a medium supplemented with excess glucose and glutamine, even though the usual stationary-phase-associated increase in sigma H was observed under these conditions.

Stimulatory effect of hormonal signaling factors on (Ca(2+)-Mg2+)-ATPase activity in rat liver plasma membranes: cross talk with regucalcin

The effect of hormonal signaling factors on (Ca(2+)-Mg2+)-ATPase activity in rat liver plasma membranes was investigated. The presence of inositol-glycan (10(-7)-10(-5) M), dibutyryl cAMP (10(-4) and 10(-3) M) or inositol 1,4,5-trisphosphate (IP3; 10(-6) and 10(-5) M) in the enzyme reaction mixture produced a significant increase in (Ca(2+)-Mg2+)-ATPase activity. These effects were completely inhibited by the presence of vanadate (10(-4) M), an inhibitor of the enzyme phosphorylation, and N-ethylmaleimide (5 x 10(-3) M), a SH group modifying reagent. Meanwhile, regucalcin, a Ca(2+)-binding protein isolated from rat liver cytosol, increased the enzyme activity by binding to the SH groups of (Ca(2+)-Mg2+)-ATPase in liver plasma membranes. The presence of regucalcin (0.25 microM) with an effective concentration completely inhibited the effect of inositol-glycan (10(-5) M) to increase (Ca(2+)-Mg2+)-ATPase activity, while the effect of dibutyryl cAMP (10(-3) M) or IP3 (10(-5) M) was not altered. The inositol-glycan effect was not modulated by the presence of dibutyryl cAMP or IP3. Now, the preincubation of the plasma membranes with regucalcin did not modify the effect of inositol-glycan on the enzyme activity, suggesting that regucalcin competes with inositol-glycan for the binding to the plasma membranes. The present results suggest that there may be a cross talk with regucalcin and hormonal signaling factors in the regulation of (Ca(2+)-Mg2+)-ATPase activity in liver plasma membranes.

Selective reduction of T cells bearing invariant V alpha 24J alpha Q antigen receptor in patients with systemic sclerosis

A novel subset of T cells characterized by the expression of an invariant T cell antigen receptor (TCR) encoded by V alpha 24J alpha Q gene segments was investigated in patients with systemic sclerosis (SSc). Polymerase chain reaction analysis demonstrated that the V alpha 24 TCR repertoire was selectively used in CD4-CD8- double-negative T cells both in patients and in healthy individuals, while almost all families of TCR V alpha were expressed in single-positive T cell fractions. The V alpha 24+ double-negative T cells were increased by approximately fivefold in patients. However, sequence analysis clearly showed significant differences in the V alpha 24 TCR repertoire dominating in patients and healthy donors. In healthy individuals, the invariant V alpha 24J alpha Q was expanded and comprised 20-50% of the total TCR-alpha, while their selective reduction was observed in SSc patients who also showed expansion of invariant V alpha 24 TCR other than V alpha 24J alpha Q. Analogous to murine invariant V alpha 14J alpha 281 TCR, these results suggest that T cells with invariant V alpha 24J alpha Q TCR would function as regulatory T cells, whereas T cells bearing other invariant V alpha 24 TCR in SSc patients could be autoaggressive T cells in nature.

Cyanamide-associated alcoholic liver disease: a sequential histological evaluation

This is the first study that we are aware of that followed the histopathological progression of the liver disease that was caused by the combination of both chronic alcohol use and cyanamide, an antidipsotropic agent. Two sequential liver biopsy specimens were obtained on 29 alcoholics who relapsed with varying histories of cyanamide treatment. Cyanamide induced ground-glass inclusions (GGIs) in the hepatocytes. Two groups were identified, depending on whether GGIs proliferated or regressed, which was, in turn, found contingent on the duration of cyanamide treatment and the drug-free period. Group 1 included 14 cases in which GGIs either emerged only in the second biopsy specimen or else were increased in the second specimen as compared in the initial specimen. Group 2 composed of 15 cases in which GGIs were either not observed in either specimen or decreased in the second specimen as compared in the initial specimen. Acidophilic bodies were sequentially increased in five cases (36%) of group 1 and in none of group 2. The severity of portal inflammation worsened in 10 cases (71%) of group 1 but in 2 cases (13%) of group 2, although the changes in fibrotic process did not differ between two groups. These differences could not be explained on the basis of the daily ethanol consumption and the length of relapses of the two groups. Thus, when cyanamide-treated alcoholics relapsed, the combined effect of cyanamide and alcohol produced the development of acidophilic bodies and portal inflammation along with the emergence of GGIs.

Instrumentational posterior fusion for atlanto-axial subluxation in a young child with Down's syndrome--case report

A 3-year-old girl with Down's syndrome and myelopathy caused by atlanto-axial subluxation (AAS) was treated by C-1 to C-2 posterior fusion with a one-piece cervical device (OPCD). Instrumentation was required because the posterior arch of C-1 was too tiny and fragile to tolerate wiring. Postoperative immobilization was another major problem in this mentally retarded young child, but a hard plastic cervical corset effectively restrained the neck. She had been confined to bed by severe quadriparesis, but became able to walk without assistance 8 months after surgery. We recommend OPCD instrumentation and postoperative immobilization using a hard plastic corset for the treatment of AAS associated with Down's syndrome in young children.

[A 78-year-old woman who had an onset of seizure and right hemiparesis at the age 77]

We report a 78-year-old woman who had an onset of convulsion and right hemiparesis at the age 77. She had been well until October 28th of 1990 when she suddenly developed a seizure starting in her right face with secondary generalization. She was admitted to Saitama Kyodo Hospital where neurologic examination revealed confusion with slight right hemiparesis; deep reflexes were exaggerated on the right side; otherwise neurologic examination was unremarkable. Cranial CT scan revealed an iso-density mass in the left motor area with extensive edema extending into left anterior frontal as well as parietal regions; by contrast enhancement, a homogeneous enhancement of the tumor was noted. She was treated with glycerol and phenytoin, and she became alert two days after her admission. The diagnosis of metastatic brain tumor was entertained; extensive malignancy survey was performed, however, no primary tumor was found. As neurosurgical procedure was refused, she was discharged on December 16th of 1990. She noted worsening of her right hemiparesis in the end of February, 1991, and she was admitted again on March 18th of 1991. On neurologic examination, she was disoriented to time and place; she was apparently demented. Her right hemiparesis was more advanced and she was unable to walk. Her hospital course was complicated by disturbance of consciousness and pneumonia, and she died on August 22nd of 1991. The patient was discussed in a neurological CPC. Opinions were divided between meningioma and a metastatic brain tumor. Other possibilities raised included malignant lymphoma and glioblastoma multiforme. As edema was very extensive on CT, many participants thought that it might be a metastatic brain tumor.(ABSTRACT TRUNCATED AT 250 WORDS)

Carboplatin-based combination chemotherapy for testicular cancer: relationship among administration dose of carboplatin, renal function and myelosuppression

Carboplatin (CBDCA), a derivative of cis-diamminedichloroplatinum, has low renal and neural toxicity. The dose-limiting factor of this agent is myelosuppression. We experienced various degrees of myelosuppression, when the dose of CBDCA was determined by the body surface area (BSA) in CBDCA-based combination chemotherapy for testicular cancer. Calvert demonstrated that the dose of CBDCA administered should be adjusted by renal function, because CBDCA was excreted through the glomerulus. We report the relationship among 3 factors; the administration dose of CBDCA, renal function and the degree of myelosuppression. We treated 6 patients with testicular cancer. A total of 22 courses of CBDCA-based combination chemotherapy was performed. The area under the curve (AUC) was calculated by the following formula, which was demonstrated in Calvert's study. CBDCA dose = AUC x (GFR + 25), GFR; glomerular filtration rate. The degree of myelosuppression was examined. All chemotherapy courses were divided into 2 and 3 groups according to BSA and AUC, respectively. WBC and Plt reduction rates and nadir counts were significantly correlated with AUC, and showed no significant relationship to the dose determined by BSA. This study revealed that the degree of myelosuppression was closely related with AUC, which reflects the renal function.

[Does a tracheal bifurcation shift upward due to increased intraabdominal pressure during laparoscopic surgery?]

To evaluate the influence of increased intraabdominal pressure on a position of tracheal bifurcation, we measured the distance from the tracheal bifurcation to the tip of the endotracheal tube which is fixed on a patient's mouth during a laparoscopic surgery. The distance decreased from 3.5 +/- 1.9 to 3.1 +/- 1.9 cm (P < 0.05) at mean intraabdominal pressure of 8.7 mmHg. This result suggests that the ventilation may become difficult due to the occlusion of the tip of the endotracheal tube by a tracheal bifurcation or due to inadvertent single lung ventilation under inappropriately deep intubation.

Control of ciliary activities of Schistosoma mansoni miracidia using Triton-extracted parasites

Extraction with 0.04% (w/v) Triton X-100 for 3 min removed the cell membrane from the locomotory cilia of Schistosoma mansoni miracidia while leaving the motile apparatus apparently intact. Immediately after Triton-extracted miracidia were treated by the reactivating solution containing ATP and magnesium ions (Mg2+) at pH 8.1, nearly 100% of Triton-extracted miracidia showed the ciliary beating and swam forward in a manner resembling that of a normal miracidium. In the standard reactivating solution (2 mM ATP, 2 mM Mg2+, pH 8.1), Triton-extracted miracidia swam at a speed of 580 microns/sec; the comparable value for live miracidia in dechlorinated tap water was 2,200 microns/sec. The swimming velocity of Triton-extracted miracidia was dependent on ATP and Mg2+ concentration, pH, and salinity. In a solution containing 0.9% NaCl, Triton-extracted miracidia were not reactivated. Among the nucleotides tested, only ATP was found to induce a significant amount of ciliary motility. In terms of divalent cation specificity, only Mg2+ was capable of producing normal motility. Barium and calcium ions (at 0.5 mM CaCl2) also were capable of activating ciliary motility but were less effective stimulants than Mg2+. However, in 1 mM CaCl2, no ciliary reactivation was observed and cilia became detached from the body surface of the miracidia. Vanadium inhibited ATP-reactivated ciliary beating of Triton-extracted miracidia.

Response of truncated glucagon-like peptide-1 and gastric inhibitory polypeptide to glucose ingestion in non-insulin dependent diabetes mellitus. Effect of sulfonylurea therapy

Gastric inhibitory polypeptide (tGIP) and truncated glucagon like peptide-1 (GLP-1) are potent gastrointestinal insulinotropic factors (incretin), are most released after a meal or ingestion of glucose in man and animals. To investigate whether sulfonylurea (SU) affects the secretion of incretin, the modulation of plasma GIP and tGLP-1 levels following glucose ingestion in non-insulin-dependent diabetic type 2 patients with or without SU therapy was studied. A 75-G oral glucose tolerance test (OGTT) was carried out on 9 healthy subjects (controls) and 18 patients with non-obese type 2, 9 of whom were treated by diet alone (NIDDM-diet) and the other 9 with SU (glibenclamide 2.5 mg or gliclazide 40 mg) once a day (NIDDM-SU). Plasma GIP was measured by radioimmunoassay (RIA) with R65 antibody, and GLP-1 was measured by RIA with N-terminal-directed antiserum R1043 (GLP-1NT) and C-terminal-directed antiserum R2337 (GLP-1CT). Following OGTT, plasma glucose, GIP, GLP-1NT, and GLP-1CT in type 2 patients increased more markedly than in controls, despite the lower response of insulin. However, there were no significant differences in plasma levels of these peptides between the NIDDM-diet and NIDDM-SU groups. Therefore, it is unlikely that SU is involved in the high response of GIP and GLP-1s to OGTT in type 2 patients.

Dose response of plasma insulin and glucagon to intravenous n-butyrate infusion in sheep

n-Butyrate (0, 1, 2, 4, 8, 16, 32, and 64 mumol.kg BW-1.min-1) was infused i.v. for 30 min to investigate the physiological effects of n-butyrate on plasma insulin and glucagon responses in sheep. Blood n-butyrate concentrations during n-butyrate infusion increased (P < .01) with increasing infusion rates. At the greater infusion rates of n-butyrate, plasma glucose concentrations increased (P < .01) during infusion, and then they decreased (P < .05) to less than the preinfusion values. Plasma insulin concentrations increased (P < .01) dose-dependently during n-butyrate infusion at rates of > or = 2 mumol.kg BW-1.min-1. Plasma glucagon concentrations increased (P < .05) during n-butyrate infusion at rates of 32 and 64 mumol.kg BW-1.min-1. It is possible that, in sheep, n-butyrate may have a physiological role in controlling insulin secretion; however, it does not seem to have a role in glucagon secretion.

An adult case of lymphangiomatosis of the mediastinum, pulmonary interstitium and retroperitoneum complicated by chronic disseminated intravascular coagulation

Pulmonary lymphangiomatosis is a rare clinical and pathological entity which is distinct from lymphangiomyomatosis and from pulmonary lymphangiectasis. We report a case of a 20 year old man with diffuse lymphangiomatosis involving the mediastinum, lungs and retroperitoneum. The patient's intrathoracic lymphangiomatosis produced restrictive and obstructive impairment of his pulmonary function, but did not result in chylothorax or chylopericardium, which are two common manifestations of the disease. The patient's clinical course was remarkable for the concomitant development of chronic disseminated intravascular coagulation (DIC). Lymphangiomatosis involving both the mediastinum and pulmonary parenchyma is rare, and DIC is a very unusual complication of lymphangiomatosis.

[Two cases of superficial siderosis of the central nervous system. Findings of the cerebrospinal fluid, magnetic resonance imaging and positron emission tomography]

Two cases (case 1, a 45-year-old man; case 2, a 68-year-old man) of superficial siderosis of the central nervous system are presented. Main neurological symptoms were anosmia, sensorineural deafness, dysarthria, ataxia, and pyramidal tract signs. Lumbar puncture revealed bloody cerebrospinal fluid (CSF) in both cases. In case 1, the CSF became watery clear after administration of hemostatic medicines. T2-weighted magnetic resonance images showed cerebellar atrophy and marginal hypointensity of the brainstem, cerebellum, and the entire spinal cord. T2-weighted images of the cranial nerves showed hypointensity of the VIII nerves which were clinically impaired as compared with normointensity of the VII nerves which presented no clinical symptom. These findings may reflect difference in the degree of hemosiderin depostion between the VII and VIII nerves. While case 1 had a borderline score of WAIS-R (IQ79), case 2 showed overt dementia (performance IQ65). Positron emission tomography showed that cerebral blood flow and cerebral oxygen metabolism were reduced in the basal temporal lobes in both cases.

Genetic association of the very low density lipoprotein (VLDL) receptor gene with sporadic Alzheimer's disease

A specific isoform of apolipoprotein E has been associated with the accelerated rate of disease expression of sporadic Alzheimer's disease (AD) and late-onset familial AD (FAD). An earlier age at onset has also been demonstrated in familial AD patients with mutations in the amyloid precursor protein (APP) gene (APP717 and APP670/671)13 carrying the APOE epsilon-4 allele compared to those who do not, but not in familial AD patients with APP692 or 693 mutations, or in chromosome 14-linked familial AD patients. Hypothesizing that receptors for apoE-containing lipoproteins act as a potential risk factor for AD, we performed an association study using a polymorphic triplet (CGG) repeat in the gene for the VLDL receptor (VLDL-R), a receptor for apoE-containing lipoproteins. The frequency of the 5-repeat allele was significantly higher in all of the Japanese sporadic AD patients (P < 0.02) than in the Japanese controls. Moreover, the odds ratio was significantly increased in the AD patients homozygous for the 5-repeat allele (OR = 2.1, 95% CI = [1.1-4.2]). Multiple logistic regression analysis reveals that the relative risk conferred by the presence of two copies of the 5-repeat allele and at least one copy of the APOE epsilon-4 allele is 8.7 (95% CI = [2.9-25.8]). Our results suggest that the VLDL-R gene is a susceptibility gene for AD.

Surface-coil magnetic resonance imaging of the internal auditory canal and the inner ear. Preliminary report

Parasagittal surface-coil magnetic resonance imaging of the internal auditory canal and the inner ear was performed. We used T2-weighted fast spin-echo sequences to visualize the inner ear and the individual nerves in the internal auditory canal with high contrast in a short acquisition time. Computer-assisted quantitative measurement of the nerves was performed to estimate the cross-sectional areas and the diameters of the nerves. The average diameters of the facial nerve, the cochlear nerve, and the vestibular nerve of normal-hearing individuals were, respectively, 1.1 +/- 0.2 mm (mean +/- SD), 1.2 +/- 0.2 mm, and 1.5 +/- 0.2 mm. In the cerebellopontine angle, the average diameter of the eighth nerve was 1.8 +/- 0.2 mm. Two patients with unilateral and bilateral hearing loss were also presented. In the patient with unilateral deafness, the cochlear nerve of the diseased side was not identified and the eighth cranial nerve diameter was smaller than that of the normal side. In the patient with bilateral deafness, fibrosis of the inner ear and atrophy of the eight nerve were demonstrated in the ear with posttraumatic deafness. The present method may represent a new approach to the assessment of pathologic processes involving the inner ear and the nerves in the internal auditory canal.

Structural and thermotropic properties of calcium-dimyristoylphosphatidic acid complexes at acidic and neutral pH conditions

Two kinds of calcium-dimyristoylphosphatidic acid (DMPA) complexes at acidic and neutral pH conditions were prepared in the following ways. The complex at pH 4 was obtained by adding Ca2+ to DMPA dispersion in pure water. On the other hand, the complex at pH 7.4 was obtained by adding Ca2+ to DMPA dispersion in the presence of NaOH. The stoichiometries of Ca2+ ion to DMPA molecule are 0.5-0.67 and approximately 1 for the complexes at pH 4 and 7.4, respectively. Static x-ray diffraction shows that the hydrocarbon chains of the Ca(2+)-DMPA complex at pH 4 at 20 degrees C are more tightly packed than those of the complex at pH 7.4 at 20 degrees C. Furthermore, the complex at pH 4 at 20 degrees C gives rise to several reflections that might be related to the ordered arrangement of the Ca2+ ions. These results indicate that the structure of the complex at pH 4 is crystalline-like. In the differential scanning calorimetry (DSC) thermogram, the complex at pH 7.4 undergoes no phase transition in a temperature range between 30 and 80 degrees C. On the other hand, in the DSC thermogram for the complex at pH 4, a peak appears at 65.8 degrees C in the first heating scan. In the successive second heating scan, a transition peak appears at 63.5 degrees C. In connection with the DSC results, the structural changes associated with these phase transitions were studied with temperature-scan x-ray diffraction. In the first heating scan, although a peak appears at 65.80C in the DSC thermogram, the hydrocarbon chain packing gradually converts from an orthorhombic lattice to a hexagonal lattice near 52 degree C, and successively the chain melting phase transition occurs near 670C. In the second heating scan, the hydrocarbon chains are packed in a hexagonal lattice over the whole temperature range and the chain melting phase transition occurs near 63.5 degree C. Therefore,the Ca2+-DMPA complex at pH 4 has a metastable state. The metastable state transforms to a stable state by maintaining the complex at pH 4 for about 90 h at 200C.