Effect of detergent on protein structure. Action of detergents on secondary and oligomeric structures of band 3 from bovine erythrocyte membranes.

With special interest in the mode of action of zwitterionic detergents on proteins, a variety of detergents were examined for their ability to disrupt the secondary and quaternary structures of an anion transport protein, band 3, and its cytoplasmic 38 kDa fragment from bovine erythrocyte membranes and for their effect on the binding of an anion transport inhibitor to band 3. Nonionic detergents and Chaps also acted as a nondenaturant in these instances, as well accepted for other proteins. Though deoxycholate and cholate inhibited the binding of an anion transport inhibitor to band 3, these detergents did not show any effect on the native structure of band 3. Zwitterionic detergents (Zwittergent 3-10, Zwittergent 3-12 and N, N-dimethyl-N-dodecyl glycine) were suggested to denature the water-soluble 38 kDa fragment at concentrations above the critical micelle concentration, but to be weak in disrupting interacting forces between hydrophobic membrane-bound domains of band 3. The results indicated that these zwitterionic detergents are similar in the mode of denaturing action to dodecyltrimethylammonium bromide rather than sodium dodecyl sulfate.

Determination of polypeptide chain molecular weights of human and bovine band 3 protein from erythrocyte membranes by low-angle laser light scattering combined with high-performance gel chromatography in the presence of sodium dodecyl sulfate.

Polypeptide chain molecular weights of human and bovine band 3 proteins which are glycoproteins of the erythrocyte membrane were determined as 101,000 +/- 2000 for the former and 107,000 +/- 2000 for the latter by using the low-angle laser light scattering technique combined with a high-performance gel chromatography column, an ultraviolet spectrophotometer and a differential refractometer in the presence of sodium dodecyl sulfate. The advantage of this method is that, unlike the sedimentation equilibrium technique, neither information on the binding to proteins of all ligands present nor the partial specific volume is required to evaluate the polypeptide chain molecular weight of proteins in a multicomponent system.

Effect of stilbenedisulfonate binding on the state of association of the membrane-spanning domain of band 3 from bovine erythrocyte membrane.

The membrane-spanning domain of bovine band 3, the anion transport protein of erythrocyte membrane, was purified in the presence of nonaethyleneglycol lauryl ether (C12E9) and the effect of a covalent attachment of 4,4'-diisothiocyanostilbene-2,2'-disulfonate (DIDS), a potent transport inhibitor, on the state of association of the domain isolated (the 58 kDa fragment) was studied via gel filtration, gel electrophoresis and sedimentation velocity experiments. It was indicated that the DIDS-unlabeled fragment in C12E9 solution forms heterogeneous aggregates which are larger in size than the dimer. This contrasted with the behavior that bovine band 3 is present as dimers or tetramers in the same medium (Nakashima and Makino (1980) J. Biochem. 88, 933-947). When DIDS was covalently attached, the fragment was present as a single molecular species which was indicated to be a dimer by molecular weight determination. The secondary structure of the fragment was not affected by DIDS. The change in the state of association caused by the DIDS-binding was also found in the presence of sucrose monolaurate (SE12), which was a more potent detergent for extraction of the 58 kDa fragment from membranes than C12E9. However, the complex with SE12 was extremely unstable.

Expression, purification, and characterization of the functional dimeric cytoplasmic domain of human erythrocyte band 3 in Escherichia coli.

The cytoplasmic domain of the human erythrocyte membrane protein, band 3 (cdb3), contains binding sites for hemoglobin, several glycolytic enzymes, band 4.1, band 4.2, and ankyrin, and constitutes the major linkage between the membrane skeleton and the membrane. Although erythrocyte cdb3 has been partially purified from proteolyzed red blood cells, further separation of the water-soluble 43-kDa and 41-kDa proteolytic fragments has never been achieved. In order to obtain pure cdb3 for crystallization and site-directed mutagenesis studies, we constructed an expression plasmid that has a tandemly linked T7 promoter placed upstream of the N-terminal 379 amino acids of the erythrocyte band 3 gene. Comparison of several Escherichia coli strains led to the selection of the BL21 (DE3) strain containing the pLysS plasmid as the best host for efficient production of cdb3. About 10 mg of recombinant cdb3 can be easily purified from 4 L of E. coli culture in two simple steps. Comparison of cdb3 released from the red blood cell by proteolysis with recombinant cdb3 reveals that both have the same N-terminal sequence, secondary structure, and pH-dependent conformational change. The purified recombinant cdb3 is also a soluble stable dimer with the same Stokes radius as erythrocyte cdb3. The affinities of the two forms of cdb3 for ankyrin are essentially identical; however, recombinant cdb3 with its unblocked N-terminus exhibits a slightly lower affinity for aldolase.

Local structural difference between human and bovine band 3 in the anion transport inhibitor-binding region.

We have examined molecular properties of inhibitor-complexed human and bovine band 3, an anion transport protein of erythrocyte membrane, in order to demonstrate the structural characteristics of the inhibitor binding region. Band 3 modified with DIDS (4,4'-diisothiocyano-2,2'-stilbenedisulfonate), a potent anion transport inhibitor, generated a positive circular dichroic band at a wavelength of 345 nm, corresponding to a DIDS chromophore. The dichroic spectra of human band 3-DIDS complex and its bovine counterpart differed markedly in their ellipticity. Under the conditions that H2DIDS (the dihydro-derivative of DIDS) cross-linked two chymotryptic fragments of human band 3, the reagent failed to cross-link the equivalent bovine fragments. The inhibitory effect of PLP (pyridoxal 5'-phosphate), a substrate and affinity label, on phosphate influx into red blood cells was more pronounced for human band 3 than for bovine band 3. The residue Lys-562 of human band 3 was found to be modified with PLP, while the corresponding residue of bovine band 3 was devoid of reactivity with PLP.

Inhibitory effect of microfibril wheat bran on azoxymethane-induced colon carcinogenesis in CF1 mice.

Microfibril wheat bran (MFW), a processed dietary fiber prepared by milling of coarse wheat bran (WB), is softer and has a more pleasant taste than WB. In this study, we examined the inhibitory effect of MFW on azoxymethane (AOM)-induced colon carcinogenesis in female CF1 mice and compared its effect with that of WB and cellulose (CL). The mice were fed a modified AIN 76 A diet supplemented with either MFW, WB, or CL at a final concentration of 20% (w/w). Six weekly s.c. injections of AOM (10 mg/kg body weight) were administered per mouse commencing 1 week after the start of the feeding period. Control mice were injected with saline only. Thirty-three weeks after the initial injection, the mice were sacrificed, examined for tumors, and the cecal contents were analyzed to determine the moisture content and the concentrations of short-chain fatty acids (SCFA). The average number of total tumors per mouse in the MFW (2.9 +/- 0.6, P = 0.017) and WB (5.3 +/- 1.3, P = 0.373) diet groups was lower than that of the CL diet group (7.5 +/- 1.3), though there was no significant difference in tumor incidence (94.7%, 90.0% and 94.7%, respectively) between the groups. More than 90% of the tumors in each group were adenocarcinomas. The incidence of adenoma and that of carcinoma in situ in the MFW diet group (5.3% and 0%, respectively) were also lower than those in the CL diet group (26.3 and 26.3%, respectively; P = 0.180 and P = 0.046, respectively). Analysis of the cecal contents revealed a significantly higher moisture content and significantly higher concentrations of SCFA, butyrate in particular, in the MFW and WB diet groups. The results of this study indicate that the source and texture of dietary fiber can influence tumor development in CF1 mice, and more specifically that MFW is a promising and useful dietary supplement with properties serving to protect against the development of colon cancer.

Peripheral or central administration of motilin suppresses LH release in female rats: a novel role for motilin.

Motilin is secreted in a clear episodic pattern during fasting or during the interdigestive phase, but feeding promptly stops this secretory pattern, and plasma concentrations of motilin decrease. We have previously determined that fasting markedly suppresses pulsatile luteinizing hormone (LH) secretion in female rats in the presence of oestrogen. In the present study, we wished to learn if motilin may mediate the fasting-induced suppression of LH secretion by determining the effects of motilin administration on LH release and on food intake. Intravenous (i.v.) injection of motilin (37 nmol/rat) suppressed LH release and significantly decreased mean LH concentrations both in ovariectomized (OVX) and oestradiol-implanted ovariectomized (OVX+E2) rats. Food intake was significantly increased by i.v. motilin injection in OVX rats, but not in OVX+E2 rats. It is likely that motilin inhibits LH release via inhibition of the gonadotrophin-releasing hormone (GnRH)-releasing mechanism at the hypothalamic level, because motilin (3.7 nmol/rat) also suppressed LH secretion when centrally administered, and because LH release in i.v. motilin-treated rats increased in response to exogenous GnRH. These results suggest that motilin may be a peripheral signal for the suppression of LH secretion through central sensors.

Intracerebroventricular administration of melanin-concentrating hormone suppresses pulsatile luteinizing hormone release in the female rat.

Melanin-concentrating hormone (MCH) has been reported to be involved in the regulation of feeding behaviour in rats and mice. Because many neuropeptides that influence ingestive behaviour also regulate reproductive function, the present study was designed to determine if central administration of MCH changes pulsatile secretion of luteinizing hormone (LH) in the rats. Wistar-Imamichi strain female rats were ovariectomized and implanted with oestradiol to produce a moderate inhibitory feedback effect on LH release. The effects of i. c.v. injections of MCH on LH release were examined in freely moving animals. Blood samples were collected every 6 min for 3 h through an indwelling cannula. After 1 h of sampling, MCH (0.1, 1 or 10 microg/animal) or vehicle (saline) was injected into the third cerebroventricle. Because MCH is also reported to affect the hypothalamo-pituitary-adrenal (HPA) axis, which in turn, can influence reproductive function, plasma corticosterone concentrations were determined in the same animals at 30-min intervals during the first and last hours and every 12 min during the second hour of the 3-h sampling period. When expressed as per cent changes, mean plasma LH concentrations after MCH administration were significantly lower in the animals injected with all doses of the peptide compared with vehicle-treated animals; LH pulse frequency was significantly lowered by 1 microg of MCH. Per cent changes in mean plasma corticosterone levels were not significantly affected by MCH administration. These results in oestradiol-treated ovariectomized rats indicate that central MCH is capable of inhibiting pulsatile LH secretion. We have previously shown that 48-h fasting suppresses pulsatile LH release in the presence of oestrogen. Take together, these results raise the possibility that MCH could play a role in mediating the suppression of LH secretion during periods of reduced nutrition.

Proteolytic digestion of band 3 from bovine erythrocyte membranes in membrane-bound and solubilized states.

Bovine band 3 in membrane-bound and solubilized states was digested with chymotrypsin, trypsin, and papain. Bovine band 3 in red blood cells was fragmented by the proteases in a 5 mM NaH2PO4-Na2HPO4 buffer containing 0.3 M glucose, pH 8.0, but not in a 5 mM NaH2PO4-Na2HPO4 buffer containing 0.15 M NaCl, pH 8.0, in which human band 3 is cleaved by chymotrypsin and papain. When compared with the known data for human band 3, however, major fragments of bovine band 3 derived from intact cells, inside-out vesicles and unsealed ghosts were similar to those of human band 3, except that tryptic fragments were formed on the extracellular attack. The results suggest that bovine band 3 adopts a quite similar molecular arrangement in the membrane to in the human case. However, it was strongly suggested by molecular weight evaluation of fragments that the only detectable water-soluble 38,000-39,000 dalton fragment does not account for the entire hydrophilic pole of the band 3 molecule exposed in the cytoplasmic region of the membrane. When isolated band 3 was treated with the enzymes in a 2% solution of nonaethyleneglycol n-dodecyl ether, the major product was indistinguishable on sodium dodecyl sulfate-gel from the water-soluble fragment of the cytoplasmic domain origin of band 3. This fragment lost its resistance to further enzymatic degradation when treated with dimethylmaleic anhydride, thus band 3 oligomers were converted into their monomers. The chymotryptic 38,000 dalton water-soluble fragment obtained in nonaethyleneglycol n-dodecyl ether solution was a subfragment of a 50,000 dalton piece which was produced in a 2% solution of deoxycholate after chymotrypsin treatment of band 3.

Germination-specific cortex-lytic enzymes from Clostridium perfringens S40 spores: time of synthesis, precursor structure and regulation of enzymatic activity.

Germination-specific enzymes, an amidase and a muramidase, of Clostridium perfringens S40 were synthesized at the time of forespore formation during sporulation. The amidase had a unique precursor structure consisting of four domains: the N-terminal pre-sequence, the N-terminal pro-sequence, mature enzyme and the C-terminal pro-sequence. The N-terminal pre-sequence and the C-terminal pro-sequence were sequentially processed at the time of development of phase-bright spores, and the resulting inactive pro-enzyme was activated by cleavage of the N-terminal pro-sequence with a specific protease during germination. A possible mechanism for the regulation of activity of muramidase, which is produced as a mature form and does not need processing for activation, is presented.

Localization of germination-specific spore-lytic enzymes in Clostridium perfringens S40 spores detected by immunoelectron microscopy.

The localization of germination-specific spore-lytic enzymes, an amidase and a muramidase, in Clostridium perfringens S40 spores was examined by immunoelectron microscopy with respective antisera raised against the enzymes and a colloidal gold-immunoglobulin G complex. For both antisera, immunogold particles were visualized on the outside of the cortex of dormant spores, and they were not detected in germinated spores and decoated spores.

A rat model for the energetic regulation of gonadotropin secretion: role of the glucose-sensing mechanism in the brain.

Energy availability has been considered to regulate gonadal activity by modulating the release of gonadotropin-releasing hormone (GnRH)/luteinizing hormone (LH) at various reproductive phases, such as lactation and puberty in domestic as well as wild animals. Experimental models with rats and sheep have demonstrated that fasting or glucoprivation suppresses pulsatile LH release. From those experiments, the information on energy deficiency is considered to be detected by specific central sensors and conveyed to the hypothalamus to regulate LH release as well as food intake. Noradrenergic neurons, originating in the medulla oblongata and projecting to the hypothalamic paraventricular nucleus (PVN), is reported to be one of the pathways mediating the response of LH release to energy deficiency. The other component is considered to be an energy-sensing mechanism in the brain. Glucose or other oxidizable fuels may function as a metabolic signal to regulate LH release. Previous studies suggest the presence of a glucose-sensing mechanism in the rat hindbrain. From our previous results in the rat, the ependymocytes lining the wall of the cerebroventricle could possibly serve as a glucose sensor to regulate GnRH/LH release. Greater understanding of the nature of the energy-sensing mechanism in the brain will contribute to the nutritional manipulation of reproductive performance in domestic animals in various conditions.

[A case of a large thoracic epidural hourglass neurinoma, incidentally detected on routine chest roentgenogram--with respect to the surgical approach].

In case of the advanced extension into the thoracic cavity, it has been difficult to remove a large thoracic spinal hourglass tumor by conventional laminectomy, even adding costotransversectomy, due to high risk of injuring diverse important vessels and other organs by blind manipulation. A case of a large thoracic spinal hourglass neurinoma with advanced extension into the mediastinum is presented. A 49-year-old female was admitted for the further examination of the left mediastinal tumor, incidentally detected on routine chest roentgenogram, which was suspected as the part of spinal hourglass tumor. Her neurological examination was normal except hyperreflexia of bilateral lower extremities. Plain chest roentgenogram showed a left mediastinal mass behind the aortic arch and the descending aorta, which slightly enlarged in size, compared with its previous size in the chest film taken 3 years ago. Thoracic spine tomogram showed the destruction of the left pedicle of T4, the absorption of posterior aspect of the T4 vertebral body and the dilatation of the left intervertebral foramen between T4-T5. Myelogram showed the complete block of dye column at T4. Metrizamide CT scan revealed the large extradural hourglass tumor, which compressed the dural theca anterolaterally and extended through the dilated left T4-T5 intervertebral foramen into the left mediastinum and attached to the descending aorta. Two stage operation, the first for the removal of the left mediastinal tumor by transthoracic approach and the second for intraspinal canal tumor by posterior approach, was performed with success for this large thoracic spinal hourglass tumor.(ABSTRACT TRUNCATED AT 250 WORDS)

[Transthoracic approaches to the lesions of thoracic cord and thoracic vertebrae].

Experiences of transthoracic approaches to the thoracic cord lesions were reported. Since 1983, we have performed six transthoracic approaches to the thoracic lesions; one thoracic OPLL, one dumbbell-shaped neurinoma, two thoracic soft disc, one epidural metastatic tumor to thoracic vertebrae. From the viewpoint of surgical anatomy, the thoracic vertebrae show a physiological kyphosis and the subarachnoid space of the ventral site is narrower than that of the dorsal site. Due to such anatomical characteristics, the thoracic laminectomy for decompression is not so effective as in the cervical or lumbar region and a relatively small mass lesion can bring a paraplegic state. The lesion of the ventral site of the thoracic cord has been regarded as no man's land because of poor results of posterior approaches. Instead of posterior approaches, anterior or anterolateral approaches with transthoracic route have been adopted. In the present paper, we used transthoracic anterolateral approaches for four patients and anterior sternum-splitting approach for two patients. The operative procedures of the approaches were described in detail. By these approaches, we could treat four patients with favourable results but the result of thoracic OPLL was poor. The cause of this poor result seemed to depend upon the intraoperative compression of the thoracic cord. For the troublesome complication, we described the postoperative cerebrospinal fluid leakage into thoracic cavity with respiratory disturbance. Several devices to prevent such troublesome complication were discussed.

[A case of intracerebral and subarachnoid hemorrhage of unknown origin with preceding headache].

We report a case of a 31-year-old female with multiple intracerebral hemorrhage and subarachnoid hemorrhage. She presented with headache one week before hemorrhage, and a CT scan performed at that time showed no abnormal findings. Neurological examination on admission revealed mild disturbance of consciousness, papilledema, and mild left hemiparesis. CT scans demonstrated intracerebral hemorrhage in the right caudate head and left frontal subcortex, and diffuse subarachnoid hemorrhage. Cerebral angiogram and laboratory examination revealed no abnormal findings. Erythrocyte sedimentation rate, C reactive protein and antiphospholipid antibody were within normal ranges. The patient underwent removal of hematoma by craniotomy. One week after the operation, a subcutaneous hematoma in the area of the craniotomy was found. Cerebral angiography demonstrated an aneurysm of the right superficial temporal artery, which was remote from the craniotomy. This aneurysm was surgically removed and examined. Histopathological examination revealed the presence of a pseudoaneurysm but no inflammation. Although primary angitis of the central nervous system was suspected to be the cause of this disease, a definite diagnosis could not be obtained.

[Another mishap with Mera-F Circuit: a break in the socket].

Troubles with the inspiratory limb have been noted with the reuse of the Mera-F Circuit. However, to our knowledge there have been no reports of the mishap in socket that is made of polycarbonate material. The case we present is a mishap due to the fracture of socket with the reuse of the circuit under general anesthesia. After the operation, the breaks were discovered in four of six other circuits reused. Although the cause of the break is unknown, it is speculated that enflurane or ethylene oxide gas may impair the polycarbonate material. Clinically, we recommend that Mera-F Circuit should be inspected carefully before its reuse.

[A case of advanced gastric remnant carcinoma with Virchow's metastasis treated with neoadjuvant chemotherapy (low dose CDDP + 5-FU) followed by surgical resection].

The patient was a 64-year-old woman. At hospitalization she had gastric remnant carcinoma with Virchow's and paraaortic lymph node metastases, extensive local infiltration and obstructive jaundice. The lesions were considered nonresectable, and the patient was placed on neoadjuvant chemotherapy consisting of low-dose CDDP and 5-FU, which resulted in the disappearance of Virchow's and paraaortic lymph node metastases. She was considered to have a partial response (PR) and underwent lower esophageal resection, total remnant gastrectomy and splenectomy. Eight months after surgery, however, she died of disseminated carcinomatosis of bone marrow. Since this therapy was associated with only slightly adverse events (< or = Grade 1), this treatment modality appears to be safe. However, further studies will be necessary to identify what type of recurrence is responsive to this therapy and to evaluate its effect on patient survival.