Could CuB be the site of redox linkage in cytochrome c oxidase?

This paper explores the proton pumping function of cytochrome c oxidase [ferrocytochrome-c:oxygen oxidoreductase (EC 1.9.3.1)] based upon redox linkage at the "high-potential" CuB center. A model is proposed that is derived from a redox-linked ligand exchange mechanism previously described for the CuA site. Qualitative analysis of this mechanism indicates that such a mechanism is feasible. However, the relatively short distance between CuB and cytochrome a3 implies that the uncoupling electron transfers are quite facile. In addition, the position of the CuB center with respect to the inner mitochondrial membrane argues against redox linkage at the CuB site.

The effects of p-hydroxymercuribenzoic acid modification and heat treatment on the CuA reduction potential of cytochrome c oxidase

p-Hydroxymercuribenzoic acid modification of cytochrome c oxidase converts the CuA center into a type 2 copper site while heat treatment of the oxidase in lauryl maltoside can transform CuA almost stoichiometrically (greater than 90%) to a blue type 1 copper site. These modifications of the protein have previously been shown to have a profound effect on the dioxygen reduction and proton pumping activities of the enzyme (Li, P. M., Morgan, J. E., Nilsson, T., Ma, M., and Chan, S. I. (1988) Biochemistry 27, 7538; Nilsson, T., Gelles, J., Li, P. M., and Chan, S. I. (1988) Biochemistry 27, 296; Sone, N., and Nicholls, P. (1984) Biochemistry 23, 6550). In this work, the intrinsic reduction potentials and the midpoint reduction potentials of the "CuA" site in both these modified oxidases have been measured under various conditions in order to clarify the intramolecular electron transfer pathways in these systems. The study reveals that the CuA intrinsic reduction potential decreases by almost 150 mV upon p-hydroxymercuribenzoic acid modification whereas it increases by 100 mV upon heat treatment. In addition, the redox interactions between CuA and the remaining metal centers are perturbed upon CuA modification. It is argued that these results bear on the role of CuA in the proton-pumping paradigm of cytochrome c oxidase.

Hyper-resistance to nitrogen mustard in Saccharomyces cerevisiae is caused by defective choline transport

The recessive hnm1 mutant allele is responsible for hyper-resistance to nitrogen mustard in Saccharomyces cerevisiae. Transformation with a single-copy HNM1 wild-type allele of such hyper-resistant mutants will restore wild-type sensitivity to nitrogen mustard. By contrast the presence of multi-copy vectors containing HNM1, in either a hyper-resistant hnm1 mutant or an HNM1 wild-type, will lead to a novel, mustard-sensitive phenotype unrelated to defects in DNA repair genes. Gene disruption of HNM1 revealed that this gene is non-essential for cells prototrophic for choline (CHO1) but lethal for cells with a cho1 genotype. Sensitivity to nitrogen mustard of wild-type HNM1, but not of hnm1 mutants, depends on the choline content of the growth medium, with cells grown in choline-free medium exhibiting the highest sensitivity. Sequencing of a 300 bp DNA fragment of HNM1 revealed the identity of this gene with the CTR locus, which is responsible for choline transport in Saccharomyces cerevisiae.

Cryosurgery in 50 cases of tongue carcinoma

From March 1975 to October 1985, 50 patients with primary tongue carcinoma were treated by cryosurgery. Forty-seven had squamous cell carcinoma, and 3 had other types of malignant tumors. The TNM clinical classification showed 12 patients with T1 lesions, 35 with T2, and 3 with T3. All patients were treated by cryosurgery in the outpatient clinic under local anesthesia. Three weeks after the primary tumors were controlled cryosurgically, 48 patients underwent radical neck dissections. All patients were observed for 3 to 10 years. After cryosurgery, the primary lesion disappeared in 45 (90%) patients; 5 were not controlled. The 3- and 5-year survival rates were 71.9% (23/32) and 72.3% (13/18), respectively. The recurrence rate in this series was 10% (5/50). Cryosurgery for tongue carcinoma was shown to be effective and safe.

Small-vessel pathology and anastomosis following maxillofacial firearm wounds: an experimental study

This experiment was designed to provide a biological basis for early reconstruction of maxillofacial defects caused by firearms using free vascularized flap transfer. The pathologic changes of small-vessel injury, injury mechanism, and the feasibility for early anastomosis of these vessels in the maxillofacial region following high-velocity missile wounds were studied. Dogs' faces were wounded by a steel sphere, weighing 0.7 g and 1.03 g, with an initial velocity of 1,300 m/s or 1,500 m/s. Angiography and high-speed x-ray photography were used to record the effect of injury to blood vessels and other tissues. The pathologic changes in the small blood vessels in the wounds were studied by light microscopy (LM) and electron microscopy (EM). Anastomosis of small vessels in the wound was performed at different times after injury. There were temporary cavity effects and small vascular injury in the wounds. The pathologic changes of the small vessels included microthrombus formation, endothelial loss, breaks in the internal elastic layer, and necrosis. Degeneration of cells was found to end 3 cm from the wound edge. Anastomosis of the vessels performed 3 days after injury provided good short-term patency. These results suggest that the operation for repairing facial defects should be performed 3 days after injury.

Elastic fiber components and protease inhibitors in pinguecula

The nature of the abnormal elastotic materials seen in pingueculae and their insensitivity to elastase are poorly understood. The authors investigated their composition by immunoelectron microscopy using antibodies to elastic fiber components, serum and tissue components known to be associated with elastosis in other sites. The abnormal elastic fibers showed labeling for elastin, microfibrillar protein, and amyloid P where these components never co-localize normally, indicating the fibers are not simply immature but aberrant in organization. There was mild positivity for the serum protease inhibitor alpha-1 antitrypsin at the edges of the abnormal elastic tissue and marked positivity for lysozyme. The more superficial region of pingueculae had similar elastic constituents but no fiber formation and a paucity of elastic microfibrils. The subepithelial dense concretions showed strong staining for lysozyme, the first component to be identified in these aggregates. Amyloid P and lysozyme are characteristic components of dermal elastosis, postulated to have an inhibitory effect on elastolytic processes, indirectly affecting the control of elastogenesis. The greater prominence of nonfiber-forming aggregates in pingueculae may be related to their marked deficiency of elastic microfibrils compared with dermal elastoses. This difference speaks for more severe actinic cellular damage in the poorly protected conjunctival tissue.

Functional characterization of RNA-dependent DNA polymerase and RNase H activities of a recombinant HIV reverse transcriptase

The DNA polymerase and RNase H activities of HIV reverse transcriptase are both essential for HIV replication. Although the two activities are both catalyzed by a single polypeptide, they are physically separate; i.e., the DNA polymerase resides in the N-terminal domain whereas the RNase H is localized in the C-terminal domain. The present study was undertaken to characterize the enzymatic properties of these two activities and to determine whether the two catalytic sites are also functionally distinct. We have observed that EGTA specifically stimulates, whereas CaCl2 selectively inhibits, the RNA-dependent DNA polymerase activity but that neither compound has any effect on the RNase H activity of a recombinant HIV reverse transcriptase. The stimulation of the DNA polymerase activity by EGTA is dependent on the Mg2+ concentration; the greatest stimulation is observed at low Mg2+ concentrations. Similarly, the inhibition of DNA polymerase activity by Ca2+ is influenced by Mg2+ concentration. Ca2+ inhibition can be reversed by increasing Mg2+ concentrations, suggesting the possibility that CaCl2 inhibits the reverse transcriptase activity by competing for a metal-binding site on the enzyme. The pyrophosphate analogue phosphonoformate selectively inhibits the polymerase activity but not the RNase H activity of HIV reverse transcriptase. In contrast, the RNase H activity can be selectively inhibited by deoxyadenosine 5'-monophosphate, whereas the DNA polymerase activity is not inhibited. These results suggest that the DNA polymerase and RNase activities are not only physically separate but that they are also functionally distinct.

The nature of Cux in cytochrome c oxidase

We report here extensive and accurate analyses of the copper, iron, zinc, and magnesium contents in bovine heart cytochrome c oxidase by direct current plasma atomic emission spectrometry. The precision of an individual measurement is within +/- 5%. The analyses confirm a stoichiometry of 5Cu/4Fe/2Zn/2Mg per dimer. Seven enzyme preparations treated by various methods are also analyzed to investigate the nature of Cux. It is shown that Cux is removable by either monomerization of the enzyme or subunit III depletion. This result suggests that Cux is associated with subunit III and that it plays a structural role in enzyme dimerization. EPR measurements indicate that Cux is heterogeneous and mostly reduced. In addition, we find Cux has no effect on the spectroscopic properties and electron transfer activity of the enzyme.

[Relation between cardiomyopathy and ventricular arrhythmias]

Ventricular arrhythmias (VA) with its relevant factors were studied in patients with cardiomyopathy and the relation between late potential (LP) and ventricular tachycardia (VT) was also evaluated. It is shown that the prevalence of VA was high in cardiomyopathy. However, its severity was not related to clinical symptoms, cardiac enlargement, cardiac function and level of plasma electrolytes. The relative risk and relative odds of LP positive were 7.33 and 20 times as high in patients with VT as in those without VT, respectively. The sensitivity, specificity, and accuracy of prediction to VT in LP positive patients were 66.2%, 90.9% and 80%, respectively. The patients with sustained VT and positive LP were more susceptible to sudden death. LP was useful to understand the mechanism and prognosis of VT.

Pseudoexfoliative fibrillopathy in the skin of patients with ocular pseudoexfoliation

In addition to its occurrence within the eye, pseudoexfoliative fibrillopathy has been reported in the conjunctiva and around a posterior ciliary artery. To determine whether it has a more diffuse extraocular distribution, we studied skin biopsy specimens ultrastructurally from one to three areas in 13 patients with classic pseudoexfoliation. A fibrillopathy closely resembling that in the eye was found in 11 of the 13 patients. Only one of the 13 control subjects, a 78-year-old man with advanced low-tension glaucoma, had a similar fibrillopathy. In the patients with pseudoexfoliation who were more than 70 years of age, the accompanying dermal elastosis made evaluation difficult, because the pseudoexfoliative nodules in the skin occur primarily along elastic fibers, and their morphologic characteristics appeared to be influenced by the elastotic process. These results suggest that pseudoexfoliation is a systemic process related closely to elastosis, and that further search for pseudoexfoliative fibers should be made in the elastic system of the deep tissues and internal organs.

[Effects of thyroxine on IgM production and beta-adrenergic receptor on lymphocyte in mice]

The effects of thyroxine (L-T4) on the IgM production of splenocytes in mice induced by sheep red blood cell (SRBC) were investigated by means of spectrophotometry of quantitative hemolysis (QHS). The maximum binding site number (Bmax) and affinity (Kd) of beta-adrenergic receptors (beta-Adr. R.) on splenic lymphocytes of mice under the different thyroid functional status during immune response were determined by radio-ligand combination method. The IgM production and Bmax of beta- Adr. R. of splenic lymphocytes were increased in "hyperthyroid mice" and decreased in "hypothyroid mice" as compared with the control (P less than 0.01) during the 3rd to 5th day after immunization with SRBC, but affinity of beta-Adr. R. was not changed (P greater than 0.05). It is suggested that L-T4 could increase the IgM production in lymphocytes induced by SRBC in mice. The underlying mechanism seems to involve an increasing Bmax of beta-Adr. R. on the immune cell, thus enhancing its sensitivity to catecholamine.

Salter's osteotomy for the management of joint capsule

Capsulotomy in primary Salter's osteotomy shaped by T or + and is difficult to tighten joint capsule. A new technique or L-shaped incision i.e., a L-shaped incision on the right hip and a reversed L-shaped incision on the left is designed to incise and sew the capsule. This technique can make the acetabulum fully exposed, and the capsule can be conveniently tightened with overlapping sutures. When it is combined with modified external fixation, redislocation after operation can be avoided.

Effects of repeated photic exposures on the monkey macula

The posterior pole of the eyes of rhesus monkeys was exposed to the light of an indirect ophthalmoscope. The tissue changes caused by repeated (three to five) photic injuries were compared with those produced by a single photic insult. The ophthalmoscopic and angiographic examinations showed a progressive involvement of the foveal area after multiple exposures to light. Histopathologic study showed that after one exposure the retinal pigment epithelium appeared focally atrophic. Plaques of proliferated retinal pigment epithelium could also be seen, and on the anterior surface of these plaques a layer of relatively cuboidal hypopigmented retinal pigment epithelial cells was present. With multiple exposures, focal areas of total absence of retinal pigment epithelium were seen in these eyes. The eyes that received only one exposure showed partially regenerated photoreceptor outer segments. After repeated photic exposures, the photoreceptor outer segments failed to regenerate even 6 to 8 months after the last exposure. In one eye exposed five times for 60 minutes, areas of total absence of photoreceptor cells could be seen, and the inner nuclear layer was directly apposed to Bruch's membrane. These experimental exposures to the light of an indirect ophthalmoscope were 60 to 120 minutes long and were not comparable to clinical exposures of the ophthalmoscope in patient examination. Our observation highlighted the cumulative effects of repeated light injury to the retinal pigment epithelial and photoreceptor cells and also showed the similarity between this animal model of photic maculopathy and the changes present in the eyes of human patients with atrophic agerlated macular degeneration.

Selective effects of tocainide in canine acute myocardial infarction

We examined the in vivo electrophysiologic effects of tocainide in canine acute myocardial infarction. We compared the effects of tocainide in infarcted and non-infarcted zones. The left anterior descending coronary artery of 8 dogs was ligated and bipolar ventricular electrograms were recorded from a needle electrode placed transmurally in the infarcted zone and from electrodes in the non-infarcted zone. Conduction intervals were measured from the onset of the limb lead QRS to the major deflection of the recorded electrograms in the infarcted and non-infarcted zones. Effective refractory periods were also determined. Measurements were made before, during and after intravenous infusion of tocainide in therapeutic doses 2 hours after infarct. Tocainide prolonged conduction intervals by 26-31% in the infarcted zone at peak (P less than 0.001), but by only 6% in the non-infarcted zone. Similarly, tocainide prolonged the effective refractory period by 27% (P less than 0.001) on the infarcted, but by 8% the non-infarcted zone. Tocainide had very slight effects on QRS duration. The present study shows that tocainide had selective effects in the infarcted zone on both conduction and effective refractory period. These selective effects may explain its antiarrhythmic effects in acute myocardial infarction.

Active opioid binding protein from rat brain--a glycoprotein containing alpha-methyl-D-mannoside residues

Active opioid binding protein was partially purified from rat brain by Vicia bungei Ohwi lectin (VBL). Mannose also existed in opioid receptors since the binding between opioid binding protein and VBL is specific, via alpha-methyl-D-mannoside (MeMan) residues. Since the active opioid binding protein purified by VBL chromatography was enriched about 200-folds. VBL can be used as effective purification tool which is much better than wheat germ agglutinin (WGA), a lectin commonly used in purifying opioid receptor.

Alterations of coronary vascular responses to noradrenaline, acetylcholine and isoprenaline during acute myocardial ischaemia in dogs

1. The reactivity of coronary arteries to noradrenaline (NA), acetylcholine (ACh) and isoprenaline (Iso) during acute myocardial ischaemia was studied in anaesthetized, open-chest dogs. 2. The left anterior descending coronary artery (LAD) was cannulated and perfused via an extracorporal circuit at constant flow. Ischaemia was produced by decreasing the perfusion blood flow of the LAD to 50% (moderate ischaemia) and 27% (severe ischemia) of normal. A dose of each agent which had no significant myocardial effects was chosen. Heart rate was held constant by ventricular pacing during ACh administration. 3. Under normal conditions, the infusion of NA, ACh and Iso into the LAD produced significant decreases in coronary vascular resistance (P less than 0.01). However, under either moderate or severe ischaemic conditions intracoronary NA resulted in a marked increase in coronary vascular resistance (P less than 0.01), which was completely blocked by phentolamine, an alpha-adrenoceptor blocker; intracoronary ACh and Iso did not have a significant effect on coronary vascular resistance (P greater than 0.05). 4. These results indicate that coronary arterial responsiveness to some intrinsic vasoactive substances, such as NA and ACh, is altered during acute myocardial ischaemia. This may be important in the pathophysiology of myocardial ischaemia.

Ocular survey of deaf-mute children

Through routine ocular examination of 279 Deaf-mute students in Lie De School in Guangzhou in 1988 by visual chart, Yu Zi Ping Pseudoisochromatic plate, portable slit lamp and direct ophthalmoscope, 100 persons (35.8%) were found to have ocular defects in one or both eyes. The incidence of ocular defects was higher than that of the normal populations. Among the ocular abnormalities, fundus defects occupied 28.6%, error of refraction, 17.9%. 17.9% of the eyes had the vision lower than 1.0 and the error of refraction was the main cause. Cases of hereditary syndromes were found: Usher syndrome, 2 cases; Goldenhar syndromes, 2 cases (brother and sister); Waardenburg syndrome, 1 case; von Recklinghausen's syndrome, 1 case. In comparing with the other articles, the ocular defect, visual disturbance, error of refraction, way of examination as well as types and characteristics of some syndromes were briefly discussed. The importance of special examinations for diagnosis, early correction of refractive error, avoidance of consanguineal marriage among deaf-mutes were emphasized.

[Electrophysiologic effects of sophocarpine on papillary muscle in guinea pig]

Sophocarpine prolonged the action potential duration of guinea pig papillary muscle in a dose-dependent manner. After the preparations were exposed to sophocarpine 50 mumol/L for 30 min, APD50 and APD90 were prolonged from 189 +/- 21 and 216 +/- 24 ms to 205 +/- 27 and 241 +/- 25 ms (P less than 0.01). Simultaneously, ERP was prolonged from 202 +/- 14 to 211 +/- 16 ms, although the ERP/APD90 ratio was not changed. Sophocarpine had no significant effects on other AP parameters. Propranolol did not block sophocarpine effects.

Amyloid P protein in pseudoexfoliative fibrillopathy

Amyloid P protein was demonstrated by immunostaining in all 14 samples of ocular and conjunctival pseudoexfoliative (PSX) material studied, although amyloid was not found by Congo red staining or ultrastructurally. Immunostaining of PSX aggregates for other common amyloid proteins, including amyloid A, prealbumin, and immunoglobulin light chains, was negative in most cases. In three eyes with advanced neovascular glaucoma there was irregular immunostaining of the PSX aggregates for 2-4 of these other amyloid proteins, besides diffuse staining of the iris and vitreous. Control cases of neovascular glaucoma without PSX disease showed minimal amyloid P, but similar tissue staining for prealbumin and immunoglobulin light chains, consistent with an origin from vascular leakage. The presence of amyloid P protein, a minor serum component, in PSX aggregates in all cases with or without evidence of vascular leakage, indicated a more specific association. Ultrastructural localization of the protein on the periphery of PSX fibers suggest it is not an intrinsic fiber component. Since PSX material has an immunological relation to elastic tissue, we propose that PSX fibers have peripheral binding sites for amyloid P protein, similar to those present on normal elastic fibers.

Association of elastin with pseudoexfoliative material: an immunoelectron microscopic study

Using immunoelectron microscopy, the presence of elastin and tropoelastin was demonstrated in pseudoexfoliative (PSX) material in all its classical sites on the lens capsule, ciliary non-pigment epithelium, iris epithelium and stroma, and conjunctiva. Some variability in binding affinity was seen in different sites, and labelling was more often on the periphery than the center of the PSX fibers. The elastin epitope on PSX material was more sensitive to processing than the remarkably stable epitope on mature elastic fibers. Since neither elastin nor a related component of PSX fibers, elastic microfibrillar protein, is a circulating protein, both are likely to be secreted by local ocular cells. Most of these local cells are not involved in elastogenesis normally, suggesting that an abnormal stimulus or defective regulation of matrix synthesis exists in this disease.

Dextrorotatory isomer of sotalol: electrophysiologic effects and interaction with verapamil

The dextrorotatory isomer of sotalol (d-sotalol) has class III antiarrhythmic properties with known action potential duration (APD) prolonging effects, and is largely devoid of beta-adrenergic blocking activity. We studied its electrophysiologic effects and the mechanism of its APD prolonging effects in sheep Purkinje fibers by means of standard microelectrode techniques. At all concentrations (10(-6) to 10(-4) mol/L), d-sotalol had no effect on Vmax. At 10(-6) mol/L, d-sotalol had no effect on APD. A concentration-dependent effect of 10(-5) to 10(-4) mol/L d-sotalol was found on APD. At peak effect, APD was prolonged by 56% and 49% at 50% (APD50) and 90% (APD90) of repolarization (p less than 0.01). Early afterdepolarizations (EADs) were noted at high concentration of d-sotalol (10(-4) mol/L). These EADs were increased in number by epinephrine. To assess the mechanism of APD prolongation, verapamil (2.0 X 10(-6) mol/L) was added before and after d-sotalol treatment. In the presence of verapamil, no APD prolongation was observed even at the highest d-sotalol concentration (10(-4) mol/L). Next, during APD prolongation at the highest d-sotalol concentration, we added verapamil, noticing a remarkable shortening of APD. In addition, d-sotalol-induced EADs disappeared with addition of verapamil. Thus (1) verapamil blocks d-sotalol-induced APD prolongation and EADs and (2) this may be consistent with a mechanism via slow inward current.

Specific cytotoxic activity of T lymphocyte clones derived from a patient with gliosarcoma

Eleven lymphocyte clones were established from the peripheral blood lymphocytes of a patient with gliosarcoma by means of autologous tumor stimulation and the limiting-dilution technique with recombinant interleukin-2. Ten of the 11 clones were cytotoxic against the autologous tumor cell line GI-1. Seven of the 10 clones were also cytotoxic against allogeneic brain-tumor lines and HeLa cells, one clone was cytotoxic against several target cells, and two clones were specifically cytotoxic against GI-1 and allogeneic brain-tumor cells. One of the 11 clones was not cytotoxic against any target cells tested. Lymphokine-activated killer cells induced by recombinant interleukin-2 alone exhibited cytotoxic activity against all target tumor cells tested. Surface phenotypic analysis revealed that all lymphocyte clones expressed CD3 antigen, some expressed CD4 antigen, and others expressed CD8 antigen. These clones seemed to be antigen-specific cytotoxic T lymphocyte clones. Analysis with these antigen-specific cytotoxic T lymphocyte clones may be useful in the elucidation of tumor-specific or tumor-associated antigens on autologous tumor cells.

Leiomyoepithelioma of iris pigment epithelium

A 4-year-old boy had a jet-black, nodular lesion growing in his right iris. Detailed clinical and histopathologic studies of this unusual tumor showed the lesion to be derived from the anterior iris pigment epithelium. The tumor cells appeared to be benign and exhibited characteristics of both pigment epithelium and smooth muscle. We have called this tumor "leiomyoepithelioma of iris pigment epithelium."

Lectin binding to pseudoexfoliative material and the ocular zonules

Lectin staining of pseudoexfoliative material on the lens capsule, zonules, and iris showed the presence of the beta-D-galactose (1-3) galactosamine sequence, alpha-D-galactosamine, beta-D-galactose, beta-(1-4)-D-glucosamine, and terminal sialic acid. Mono and difucosyl binding sites were also found. The likelihood that the lectins were binding to two different galactosamine-containing moieties was supported by their different distributions in the photoreceptors. These affinities suggest a complex carbohydrate composition in pseudoexfoliative material, with both O-linked sialomucin-type and N-linked oligosaccharide chains.