[Multiplanar transesophageal echocardiography in a case of hypernephroma]

A 78-year-old man admitted to our hospital with signs and symptoms of right ventricular failure, consisting of severe edema of the scrotum and the penis, ankle edema, hepatomegaly, and a history of asthenia associated with a recent weight loss. Two-dimensional echocardiography showed an intracavitary mass in the right atrium and a moderate pericardial effusion; the remaining structures were normal. To better define the origin of this mass, transesophageal echocardiography was performed. The mass extended from the inferior vena cava with no sites of attachment to the atrial wall. The mass was elongated, mobile, with a triangular termination near the tricuspid valve, without signs of right ventricular obstruction. An abdominal-pelvic CT scan demonstrated the origin of the mass at the superior pole of the left kidney extending through the renal vein and the inferior vena cava into the right atrium. The mass was surgically removed and the pathological examination revealed a renal cell carcinoma (hypernephroma) of the clear cells subtype. After surgery, the patient did well with the resolution of the picture of right ventricular failure.

Expression of proliferating cell nuclear antigen, Ki-67 antigen, estrogen receptor protein, and tumor suppressor p53 gene in cytologic samples of breast cancer: an immunochemical study with clinical, pathobiological, and histologic correlations

Sixty-six unselected breast cancers were analyzed in cytologic smears and histologic sections for the expression of Ki-67, proliferating cell nuclear antigen (PCNA), estrogen receptor protein (ERP), and p53 protein using a standard immunochemical method. The results, expressed as both positive cases and labelling index (LI), were compared with clinical and pathobiological variables. Ki-67 and PCNA immunostaining was seen in all cases, whereas ERP was detectable in 46/63 cases and p53 protein in 20/66 cases. The expression of these markers was generally lower in cytology than in histology, though the differences were not statistically significant. PCNA-LI and Ki-67-LI were closely correlated (P < 0.001), the mean PCNA:Ki-67 ratio being 0.92 +/- 0.57. Occasional discrepancies, however, were found. PCNA and Ki-67 expression was associated with an increase in histologic grade and a decrease in ERP content of tumors, whereas p53 was statistically associated with no clinical or pathobiological variables. The data suggest that proliferative activity and oncogene overexpression may be reliably evaluated in breast cancer by FNA cytology, though PCNA is not a suitable indicator for cell proliferation. The results do not resolve the issue as to whether immunostaining for p53 protein constitutes a dedifferentiation product of the tumor, or is a fundamental aspect of the malignant progression. Survival studies in a larger series of tumors are thus needed to elucidate this point.

Immunocytochemical detection of cell proliferation-related antigens in cytologic smears of human malignant neoplasms using PC10, reactive with proliferating cell nuclear antigen, and Ki-67. A comparative study

Cytospins of the MCF-7 cell line and 93 consecutive smears of human malignant neoplasms were immunochemically evaluated for the expression of proliferating cell nuclear antigen (PCNA) and Ki-67-related antigen. Results expressed as the labeling index (LI) were compared with histologic sections. The PCNA LI and Ki-67 LI were lower in cytologic smears than in histologic sections, though the differences were not statistically significant. A positive linear relationship was found between these markers in both cytologic and histologic samples. The PCNA LI was generally lower than the Ki-67 LI, but in seven malignant neoplasms, PCNA LI was greater than the corresponding values of the KI-67 LI. We conclude that cell proliferation can be reliably evaluated on cytologic preparations; PCNA may behave as a Ki-67-like reagent in some tumors, and PCNA may sometimes overestimate the cell growth fraction assessed by Ki-67 immunoreactivity.

Methodological aspects of the immunostaining of proliferating cell nuclear antigen (PCNA) in cytospin preparations of MCF-7 cell line

Cytospins of a human breast cancer cell line (MCF-7) were studied for the expression of PCNA, a cell cycle-related protein, using a variety of fixation and immunostaining procedures. The best fixative for PCNA was found to be buffered formaldehyde solution at 4 degrees C followed by methanol at 20 degrees C, whereas alcoholic fixatives decreased greatly the PCNA immunoreactivity. Air-drying procedures of cytospins prior to and after fixation greatly undermined the PCNA immunostaining. A modified immunoperoxidase method provided a stronger staining of the PCNA-reactive cells than the alkaline phosphatase anti-alkaline phosphatase (APAAP) technique. PCNA immunoreactivity could be maintained up to 2 mo, putting slides in methanol at -20 degrees C. In conclusion, our report indicates that PCNA is a labile antigen, which may critically be affected by temperature and air-drying procedures.

Detection of small-cell-lung-cancer cells in bone-marrow aspirates by monoclonal antibodies NCC-LU-243, NCC-LU-246 and MLuC1

We have used immunocytochemistry to identify tumor cells in bone-marrow aspirates of patients with small-cell lung cancer and we have compared the results with conventional histomorphology. The monoclonal antibodies (MAbs) used were NCC-LU-243 and NCC-LU-246 (cluster 1) and MLuC1 (cluster 6); 108 slides (52 patients) incubated with NCC-LU-246, 106 (51 patients) with NCC-LU-243 and 69 with MLuC1 (36 patients) were evaluated. Bone-marrow biopsies (83) were also obtained from 50 of these patients; 48/108 bone marrow aspirates were positive for cluster-1 antigen and 22/69 were positive for MLuC1. Immunocytochemistry with anti-NCAM MAbs detected bone-marrow localization in 38/83 bone-marrow aspirates compared with 9/83 bone-marrow biopsies, while MLuC1 was positive in 18/60 and bone-marrow biopsies in 6/60. Moreover, bone-marrow aspirates were positive for cluster-1 antigen in 7/17 patients with limited disease at diagnosis. Patients with positive bone-marrow biopsies had significantly shorter survival. No differences were found between patients with positive and those with negative marrow aspirates.

Detection of the neural cell adhesion molecule (NCAM) in serum of patients with small-cell lung cancer (SCLC) with "limited" or "extensive" disease, and bone-marrow infiltration

The neural cell adhesion molecule (NCAM) is a tumour-related antigen found on the surface of small-cell lung cancer (SCLC). NCAM exists in several molecular forms, including a soluble isoform. We have measured serum levels of NCAM using an enzyme immunoassay with 2 antibodies, NCC-LU-246 and NCC-LU-243, that react with different epitopes on the NCAM molecule. NCAM activity from 83 patients with active SCLC, either pre-treatment, progressing or in relapse was significantly higher than in 70 patients on follow-up. Overall, 40% of patients with active SCLC and 7% patients on follow-up had serum levels of NCAM > 2SD above controls; 61% of patients with relapsed SCLC had elevated levels of NCAM. Pre-treatment NCAM levels were significantly higher in 35 patients with "extensive" disease than in 19 patients with "limited" disease. Serum NCAM activity was also significantly higher in patients with tumour infiltration of the bone marrow. This difference could not be explained solely by the presence of "extensive" disease. Serum NSE levels in these patients were correlated with NCAM activity. The presence of raised serum NCAM in active disease and in patients in relapse suggests that this antigen could be used as a target for antibody-directed therapy of micrometastases.

Immunohistochemical identification of the uncoupling protein in human hibernoma

The expression of the uncoupling protein (UCP), a protein unique to brown adipocyte mitochondria, was studied in sections of a human hibernoma by means of immunohistochemistry. Multilocular, but not unilocular, adipocytes expressed the UCP in the tissue. Further, the immunostaining was not uniform in multilocular cells, because small adipocytes with finely multivacuolar or scanty lipid deposit showed more intense staining. This pattern is similar to that found in brown adipose tissue. Ultrastructural investigation confirmed that a majority of proliferating cells had the morphological characteristics of brown adipocyte. Results indicate that adipocytes in hibernoma may be very close to brown adipocytes both morphologically and immunocytochemically.

Expression of progesterone receptors in solid-cystic tumour of the pancreas: a clinicopathological and immunohistochemical study of ten cases

A role for sex hormones in the pathogenesis of solid-cystic tumour (SCT) of the pancreas is suggested by its predilection for young fertile women. Controversial data have been provided for the presence of progesterone receptors (PR) and/or oestrogen receptors (ER) in SCT. We report the immunohistochemical detection of PR in ten cases of SCT. Eight were from young women. The remaining two were from a post-menopausal woman and a young boy. All cases showed PR immunoreactivity in the large majority of neoplastic cells, whereas none exhibited ER positivity. In one tumour two types of cell populations were noted, the more anaplastic invasive-type being PR negative, whereas the more typical was PR positive. PR immunoreactivity in the absence of ER may simply reflect a lower sensitivity of ER antibody failing to reveal the biochemically detectable ER, or that the PR in cells of SCT are constitutively synthesized in an oestrogen-independent way, as in T47D breast carcinoma cell line, meningioma cells and some gastric cancer cells. Our findings support the hypothesis of a possible pathogenetic role of progesterone in SCT, independent of the patient's sex and age.

In vivo radiofrequency-based ultrasonic tissue characterization of the atherosclerotic plaque

BACKGROUND AND PURPOSE

The ultrasonic image can offer unique information on the composition of atherosclerotic plaque, ie, the relative content of lipids, fibrous tissue, and calcific deposits. To date, however, the echographic assessment of plaque structure is based on a subjective, qualitative evaluation of the bidimensional images. We evaluated the feasibility and accuracy of assessing, in vivo, the acoustic properties of arterial carotid plaques by means of a suitably modified echographic apparatus allowing direct access to the radiofrequency signal.

METHODS

In 15 patients undergoing carotid thromboendarterectomy, the ultrasonic findings in 70 discrete sites (within the plaque, n = 54; normal sites, n = 11; or intraluminal thrombi, n = 5) were correlated with the histological analysis (hematoxylin-eosin and Mallory trichrome stains) independently performed on the arterial samples. The pathological examination was carried out at a similar level of the insonation; the sites analyzed within the plaque were chosen because of their uniform echoic characteristics. In each ultrasonic region of interest selected from the echographic image, the integrated amplitude of the rectified radiofrequency signal was measured as the integrated backscatter index.

RESULTS

The intimal-medial layer of normal carotid wall (n = 11) exhibited values of -32.5 +/- 9.4 dB. The integrated backscatter index in fatty sites (n = 11, -40.3 +/- 5.4 dB) differed from that of fibrous (n = 12, -23.8 +/- 5.0 dB) and calcified (n = 26, -11.5 +/- 5.2 dB, P < .01 for all intergroup differences) sites. Intraluminal thrombotic sites (n = 5, -42 +/- 5.1 dB, P < .01) differed from fibrous and calcified subsets (P < .01) but overlapped (P = NS) with fatty sites. Histological sampling also showed two sites of intraplaque hemorrhage that exhibited very low backscatter values (-53 and -58 dB) and three fibrofatty sites showing backscatter values (-28, -28, and -32 dB) intermediate between the fibrous and the fatty subsets.

CONCLUSIONS

Quantitative analysis of integrated backscatter of the arterial wall is feasible in humans and provides an operator-independent assessment of plaque echoic structure. In particular, integrated backscatter is effective in distinguishing lipidic, fibrotic, and calcific components in human atherosclerotic plaques.

[An experimental model for the rational treatment of arrhythmias: a clinical study with quinidine]

Fourteen patients with supraventricular and/or ventricular ectopic beats selected by clinical, dynamic ECG and exercise test, underwent a basal continuous ECG recording (Holter) and then were given 400 mg of quinidine orally. The concentrations of the drug were determined in blood samples taken 30 minutes before, and 1, 2, 4, 6, 8, 12, and 24 hours after administration. On the same day patients were also monitored by continuous ECG recording (Holter). One week later, after a washout period, the same subjects were treated with 200 mg of quinidine orally 4 times a day for two weeks. On day 1, 2, 4, 7 and 14 quinidine was determined in plasma, and on day 7 and 14 a 24 hour ECG recording was also done. On the basis of pharmacokinetic parameters obtained from the acute test, the chronic levels of the drug were predicted. Predicted values were superimposable to those observed. Thus, the kinetics of single-dose quinidine is able to predict the steady-state levels after repeated dosing. During acute administration there was an increase in QTc interval and a decrease in ectopic beats. These effects correlated with a sigmoid pattern with acute quinidine levels. Concentrations producing 50% of the effect (EC50) could be calculated from these curves. In spite of similar steady-state blood levels of quinidine, some patients after chronic therapy did not respond to treatment (non responders). Non responders could be predicted by the acute test because they had greater EC50 values of QTc increase: patients with EC50 greater than 2 mg/L were all non responders.

Phyllodes tumor of the breast: problems of differential diagnosis and therapeutic approach from an analysis of 17 cases

Retrospective analysis of 17 cases of phyllodes tumor with a follow-up of almost 1 year revealed no close correlation between histological pattern and clinical course, since local relapse occurs even after histological findings of benign lesion in the primary tumor. Phyllodes and fibroadenoma patterns are often associated in the same patient and extensive surgery is not recommended owing to the fact that recurrences are observed both after subcutaneous mastectomy and after simple resection. We conclude that local control of the disease by wedge resection and strict follow-up may be the most rational approach.

Effect of plasma exchange in a patient with prolonged deep coma from thrombotic thrombocytopenic purpura

The clinical, laboratory and instrumental data of a patient with thrombotic thrombocytopenic purpura (TTP) are reported in detail, with reference to an articulated therapeutic regimen including plasma exchange, high-dose methylprednisolone and dipiridamole. Particular emphasis is placed on the dramatic improvement obtained with this treatment despite a very delayed diagnosis and prolonged, severe neurological involvement. A short discussion and review of the literature concerning the role of plasma-exchange in the treatment of TTP is reported.

Immunodetection of proliferating cell nuclear antigen assesses the growth fraction and predicts malignancy in endocrine tumors of the pancreas

Thirty-five endocrine tumors of the pancreas, 17 functioning and 18 nonfunctioning, were immunohistochemically studied for the expression of proliferating cell nuclear antigen (PCNA) using 19A2 and PC10 monoclonal antibodies. The proportion of PCNA-reactive cells (PCNA index) ranged from 0.2 to 27% in functioning tumors and from 0.1% to 55% in nonfunctioning tumors. PCNA index showed a statistically significant correlation with mitotic and Ki67 indexes. The median values of PCNA index identified three groups of patients: group A (PCNA < or = 2%), including 13 functioning and six nonfunctioning tumors; group B (PCNA between 2 and 5%), including three functioning and three nonfunctioning tumors; group C (PCNA > 5%), including one functioning and nine nonfunctioning tumors. All group A tumors were confined to the pancreas. In group B, the functioning tumors were limited to the pancreas, and the nonfunctioning tumors extended to extrapancreatic tissues. All group C patients had extrapancreatic extension of the disease. At follow-up, a PCNA index higher than 5% correlated to a decreased mean survival. Our data suggest that PCNA index is a reliable tool to assess the growth fraction, discern local from advanced diseases, and predict malignancy in pancreatic endocrine tumors.

Myocardial vitamin E is consumed during cardiopulmonary bypass: indirect evidence of free radical generation in human ischemic heart

Although a role for free radicals in myocardial damage during cardiopulmonary bypass for open heart surgery has been postulated, direct evidence of free radical production as well as consumption of tissue antioxidants such as vitamin E is still lacking. Twenty patients (age 26-66 yr, mean 48) undergoing elective open heart surgery with moderate hypothermia, and cold crystalloid cardioplegia, were studied. Cardiopulmonary bypass time was 61.4 +/- 31.2 min. The specimens of atrial tissue collection before and after cardiopulmonary bypass, were immediately frozen in liquid nitrogen. Mean vitamin E atrial content, measured by reverse phase HPLC, was 355 +/- 249 pmol/mg of dry weight basally, 135 +/- 85 pmol/mg (p < 0.05) at the end of the ischemic period and 405 +/- 288 pmol/mg after the reperfusion period (p < 0.01). Microscopic examination of right atrial biopsies ruled out differences in fibrosis or cellular damage as the cause of vitamin E changes. Although a great basal variability in atrial vitamin E content was observed, which was independent of age, sex and clinical status, a reproducible and substantial decrease in atrial vitamin E content after cardiopulmonary bypass occurred (mean reduction 45 +/- 17% and 55 +/- 22%, respectively, after ischemia and after reperfusion). This was directly related to the aorta cross-clamping duration and partially to the minimum temperature achieved. In conclusion, apart from the great variability observed in basal vitamin E tissue content, vitamin E was always reduced during cardiopulmonary bypass, suggesting an oxidative stress on the myocardium during open heart surgery.

Development of innumerable neuroendocrine tumorlets in pulmonary lobe scarred by intralobar sequestration. Immunohistochemical and ultrastructural study of an unusual case

We describe the microscopic, histochemical, immunohistochemical, and ultrastructural features of hundreds of neuroendocrine tumorlets occurring within a pulmonary lobe severely scarred by intralobar sequestration in a nonsmoking 49-year-old white man. To our knowledge, there have thus far been no descriptions or detailed analyses of neuroendocrine tumorlets arising within a pulmonary sequestration. The neuroendocrine tumorlets appeared in the form of minute aggregates--mostly microscopic, up to a maximum of 0.3 cm in greatest diameter--of small round and short spindle-shaped cells. They were organized in compact nests of fascicles and were supplied with round or elongated euchromatic nuclei and scant weakly eosinophilic cytoplasm. The neuroendocrine tumorlets were clustered around diseased bronchioles or embedded in a fibrotic pulmonary parenchyma with a distinctive infiltrative appearance. Sometimes they lay near an artery channel without an identifiable bronchiole or herniated into distal airways. Most of the neuroendocrine tumorlets were strongly argyrophilic on Grimelius staining. Immunohistochemically, there was reactivity for markers of epithelial and neuroendocrine differentiation together with evidence of orthotopic production of calcitonin, serotonin, and gastrin-releasing peptide and ectopic production of vasoactive intestinal peptide. Ultrastructurally, most of the neuroendocrine cells showed 100- to 120-nm dense-core membrane-bound secretory granules; mucus secretory cells were also present. We prefer the term neuroendocrine tumorlets over the generally used term carcinoid tumorlets, because the nature of these lesions is undefined and the relationship with neuroendocrine pulmonary neoplasms is not yet established.

[Brain death and prolonged fetal survival]

The Authors presents in detail a case of a 25-year-old primigravida that had fatal intracranial bleeding at the beginning of the 15th week of gestation, whose vital function are sustained for 49 days. Despite the insuccess to bring the pregnancy to a gestational period favorable to induce the delivery, they analyse the problems connected to the maternal maintenance and to the fetal growth.

Influence of selective autonomic decentralization on myocardial deoxyglucose uptake initiated by cardio-cardiac reflexes

The aim of this study was to evaluate the effect of autonomic reflexes as initiated by stimulation of the right recurrent cardiopulmonary nerve afferent axons on myocardial deoxyglucose uptake and to determine how such uptake can be modified by selective neural ablation. The afferent axon in the right recurrent cardiopulmonary nerve was stimulated 30 s/min for 1 h in five anesthetized open-chest dogs in which 14-C labeled deoxyglucose was i.v. injected at the beginning of the stimulation period. Three additional sham-operated dogs served as neurally intact controls. Concentrations of label and glucose were measured in plasma. Regional myocardial deoxyglucose concentration was measured by quantitative autoradiography, following the calibration of plasma samples autoradiographic density by beta counting. Stimulation of right recurrent cardiopulmonary nerve afferent axons in the intact nervous system preparation did not significantly enhance deoxyglucose uptake as compared to neurally intact controls. When the right cervical vagosympathetic complex was cut a similar uptake was observed. Following decentralization of the right stellate ganglion, uptake was markedly reduced, as well as when the right cervical vagosympathetic was cut and the right stellate ganglion decentralized.

CONCLUSIONS

Activation of afferent axons from cardiopulmonary receptors does not alter myocardial deoxyglucose uptake. Reduction in uptake occurs following unilateral stellate ganglion decentralization.

[A mathematical model of the vascular architecture and of the distribution of resistances in the coronary tree]

The architecture and resistance distribution of the coronary arteriolar tree downstream 100 mu diameter vessels are still largely unknown, due to technical difficulties in direct visualization. In this study we propose a mathematical model of the architecture and the single vessel resistance distribution of terminal arteriolar vasculature in the beating dog heart, based on the analysis of embolization-induced changes of total coronary resistance. Coronary embolization was performed by injecting several boluses of 15 mu (6 cases) and 25 mu (6 cases) plastic microspheres into the maximally vasodilated (adenosine infusion) left circumflex artery of the open chest dog. The relation between the number of plastic beads progressively injected to embolize 15 mu and 25 mu vessels and the resulting increase in total coronary resistance (occlusion function) was obtained in each experiment. If we consider a binary symmetric vascular tree with i) equal resistance for vessels of the same branching order and ii) optimal ratio between resistance of parent and daughter vessels at all branching sites, the simulation of embolization in such a system shows that the occlusion function of the terminal vessels N in the linear portion between 0 and N/2 occluded vessels has a slope S' which is 5.6 times lower than the slope S" between N/2 and 3/4 N occluded vessels and 3.6 times lower than the S' of the occlusion function of the preterminal vessels. The occlusion function in our experiments has a ratio S"/S' close to that predicted by the model and a ratio between the S' of the 25 mu and that of 15 mu experiments equal to 4.(ABSTRACT TRUNCATED AT 250 WORDS)

Crystal structure solution and refinement of the semisynthetic cobalt-substituted bovine erythrocyte superoxide dismutase at 2.0 A resolution

The semisynthetic Co-substituted bovine erythrocyte superoxide dismutase (SOD) has been crystallized in a new crystalline form and the structure determined at 2.0 A (1 A = 0.1 nm) resolution. The crystals belong to space group P2(1)2(1)2(1) with cell constants: a = 51.0, b = 147.6, c = 47.5 A, and contain one dimeric molecule of 32,000 M(r) per asymmetric unit. The structure has been solved by molecular replacement techniques using the Cu,Zn bovine enzyme as a search model, and refined by molecular dynamics with the crystallographic pseudo-energy term, followed by conventional crystallographic refinement. The R-factor for the 18,964 unique reflections in the resolution range from 10.0 to 2.0 A is 0.176 for a model comprising 2188 protein atoms and 200 solvent molecules; the root-mean-square deviation from the ideal bond lengths is 0.010 A, and the average atomic temperature factor is 26.5 A2. The dimeric molecule of the enzyme is composed of two identical subunits related by a non-crystallographic 2-fold axis. The subunit has as its structural scaffolding the conventional SOD-flattened antiparallel eight-stranded beta-barrel, with three external loops. The co-ordination geometry of the metal center in the active site is fairly well preserved when compared with the native Cu,Zn bovine enzyme. Co2+ is in tetrahedral co-ordination, while the Cu2+ ligands show an uneven distortion from the square planar geometry. The least-squares superposition of the metals ligands and the catalytically important Arg141 of the native and Co-substituted enzyme yields a root-mean-square value of 0.401 A, the largest deviation occurring at the Co2+ ligand Asp81. An additional copper ligand, compatible with a water molecule, is observed at 2.38 A from Cu2+ in the active-site channel, at the supposed binding site of the O2- anion substrate. Several ordered water molecules have been observed on the protein surface and in the active-site channel; their structural locations coincide remarkably with those of related water molecules found in the crystal structure of the phylogenetically distant superoxide dismutase from yeast.

Crystal structure of yeast Cu,Zn superoxide dismutase. Crystallographic refinement at 2.5 A resolution

The structure of Cu,Zn yeast superoxide dismutase has been determined to 2.5 A resolution. The enzyme crystallizes in the P2(1)2(1)2 space group with two dimeric enzyme molecules per asymmetric unit. The structure has been solved by molecular replacement techniques using the dimer of the bovine enzyme as the search model, and refined by molecular dynamics with crystallographic pseudo-energy terms, followed by conventional crystallographic restrained refinement. The R-factor for 32,088 unique reflections in the 10.0 to 2.5 A resolution range (98.2% of all possible reflections) is 0.158 for a model comprising two protein dimers and 516 bound solvent molecules, with a root-mean-square deviation of 0.016 A from the ideal bond lengths, and an average B-factor value of 29.9 A2. A dimeric molecule of the enzyme is composed of two identical subunits related by a non-crystallographic 2-fold axis. Each subunit (153 amino acid residues) has as its structural scaffolding a flattened antiparallel eight-stranded beta-barrel, plus three external loops. The overall three-dimensional structure is quite similar to the phylogenetically distant bovine superoxide dismutase (55% amino acid homology), the largest deviations can be observed in the regions of amino acid insertions. The major insertion site hosting residues Ser25A and Gly25B, occurs in the 2,3 beta-turn between strands 2b and 3c, resulting in the structural perturbations of the two neighbouring strands. The second insertion site, at the end of the 3c beta-strand in the wide Greek-key loop, hosts the Asn35A residue, having an evident effect on the structure of the loop and possibly on the neighbouring 5,4 beta-turn. The salt bridge Arg77-Asp99 and the disulphide bridge Cys55-Cys144 stabilize the loop regions containing the metal ligands. The stereochemistry of the two metal centres is conserved, with respect to the bovine enzyme. The Cu2+ ligands show an uneven distortion from a square plane, while Zn2+ co-ordination geometry is distorted tetrahedral. The imidazole ring of the His61 residue forms a bridge between Cu and Zn ions. A solvent peak compatible with a fifth ligand is observed 2.0 A away from the copper in the active site channel, which is filled by ordered water molecules that possibly contribute to the stability and function of the enzyme. The charged residues responsible for the electrostatic guidance of the substrate to the active site (Glu130, Glu131, Lys134 and Arg141) are fairly conserved in their positions, some of them showing different interactions in the four chains due to the intermolecular contacts between the dimers.(ABSTRACT TRUNCATED AT 400 WORDS)

Regional myocardial deoxyglucose uptake following electrical stimulation of canine efferent sympathetic cardiopulmonary nerves

OBJECTIVE

The aim was to study the effect of stimulating individual acutely decentralised cardiopulmonary nerves on myocardial uptake of deoxyglucose.

METHODS

In 17 open chest anaesthetised dogs the efferent axons of individual decentralised cardiopulmonary nerves were stimulated intermittently throughout 1 h while haemodynamic variables were measured. Tritiated 2-deoxyglucose was injected intravenously at the beginning of stimulation. Atropine was given when a cardiopulmonary nerve with efferent parasympathetic axons was studied. Distribution of label was detected using a multiwire proportional chamber. It was compared to blood concentration of deoxyglucose to permit quantitative mapping of regional myocardial uptake during the stimulation of each nerve.

RESULTS

Neural stimulation of most of sympathetic efferent cardiopulmonary nerves increased deoxyglucose uptake in all myocardial tissue. Uptake was greatest in the left ventricle, less in the right ventricle, and least in the left and right atria. Regional myocardial uptake was also observed following individual cardiopulmonary nerve stimulation. Some nerves caused greater uptake than others. Cardiopulmonary nerves which are known to enhance inotropism when stimulated induced little increase of deoxyglucose uptake, whereas other nerves known to exert little positive inotropic effect induced considerable uptake. There was no correlation between haemodynamic changes and deoxyglucose uptake.

CONCLUSIONS

It appears that (1) efferent sympathetic axons in one cardiopulmonary nerve can preferentially increase deoxyglucose uptake in specific regions of the myocardium and (2) the mechanisms responsible for enhancement of glucose uptake may differ from those responsible for inotropic responses.

Release of contracting autacoids by aortae of normal and atherosclerotic rabbits

The aim of our study was to examine the release of various lipid and peptide contracting autacoids by aortae of normal and atherosclerotic rabbits. Leukotriene (LT) E4, an enzymatic derivative of LTC4, thromboxane (Tx) B2, and endothelin-1 (ET-1) were measured by radioimmunoassay techniques in aortic preparations of normal and cholesterol-fed rabbits. Intact aortae of normal rabbits incubated with the calcium ionophore A23187 for 1 h at 37 degrees C released LTE4 and TxB2 (22 +/- 3.5 and 14.8 +/- 2 pg/mg of tissue, respectively, mean +/- SEM, n = 33). Removal of aortic endothelium was associated with a significant reduction in LTE4 (44%) and TxB2 (58%) release. In aortic preparations from cholesterol-fed rabbits, the release of LTE4 was significantly enhanced (41 +/- 8 pg/mg of tissue, mean +/- SEM, n = 27) whereas TxB2 was not significantly altered. No detectable amounts of ET-1 were measured after 1 h of incubation. However, at 4 h, an endothelium-dependent release of ET-1 from normal aortae was demonstrated. In atherosclerotic aortae, ET-1 release was significantly higher than in controls (10 +/- 1.3 vs. 5 +/- 0.5 pg/cm2, mean +/- SEM, n = 16). We conclude that enhanced formation of vasoconstrictor autacoids may contribute to altered vasomotion of atherosclerotic blood vessels.