Dopamine D2 receptor imaging in pituitary adenomas using iodine-123-epidepride and SPECT

Epidepride is a novel benzamide derivative with high affinity for D2 receptors. Epidepride, in its 123I-labeled form, can be used for SPECT imaging of striatal and extrastriatal dopamine D2 receptors. The present study evaluated the usefulness of epidepride and SPECT for in vivo imaging of dopamine receptors in pituitary adenomas.

METHODS

SPECT imaging was performed in 19 patients with pituitary adenomas (among them 9 patients had prolactinoma, 4 acromegaly, 4 clinically nonfunctioning pituitary adenoma, 1 Cushing's disease and 1 Nelson's syndrome) and 7 control subjects 180 min after intravenous bolus injection of 3.9 +/- 1.1 mCi [123I]epidepride. The ratio target/cerebellum minus 1, reflecting specific/ nonspecific binding was used as semiquantitative measure of D2 receptor binding.

RESULTS

Eight of nine prolactinoma patients demonstrated specific binding within the adenoma. The adenoma/ cerebellum ratio 3 hr p.i. showed a wide variation with values from 2.5-33. In three prolactinomas, binding was higher than in the striatum. Specific binding within the lower range of prolactinomas (adenoma/cerebellum ratios 2 and 4.8) could be demonstrated in two of four GH-secreting adenomas. All four nonfunctioning tumors showed specific binding. The adenoma/cerebellum ratio was within the lower range of prolactinomas (5.2-7.5) in three of these patients but extremely high in one (52.3). No specific tracer uptake could be demonstrated in patients with Cushing's disease or Nelson's syndrome. The striatum/cerebellum ratio 3 hr p.i. in pituitary adenoma patients was not significantly different from control subjects (17.3 +/- 5.5 versus 17.8 +/- 6.6; patients versus control subjects).

CONCLUSION

Epidepride appears to be an excellent ligand for in vivo imaging of dopamine D2 receptors in pituitary adenomas. Epidepride SPECT could serve as a predictor for response to dopamine agonist treatment.

The influence of growth hormone substitution therapy on erythroid and myeloid progenitor cells and on peripheral blood cells in adult patients with growth hormone deficiency

It has been reported that hypophysectomized rats exhibit normochromic, normocytic anaemia. Pancytopenia with impaired DNA synthesis in the bone marrow can be restored in these hypophysectomized rats by syngeneic pituitary grafts placed under the kidney capsule or treatment with growth hormone (GH). Until now, adults with hypopituitarism have received adequate replacement therapy with thyroxine, cortisol and sex steroids, but not with GH. We therefore investigated the effects of GH replacement therapy on the proliferation and differentiation of erythroid and myeloid progenitor and peripheral blood cells in 11 adult patients with growth hormone deficiency in a double-blind, placebo-controlled study for the first 6 months of therapy. The placebo group showed no changes during the first 6 months without therapy in either insulin-like growth factor I (IGF-I) levels, erythroid and myeloid progenitor precursor cells or peripheral blood cells. After commencement of GH therapy, IGF-I levels rose significantly during 24 months of therapy from 75.3 +/- 13.5 to 225 +/- 34.7 ng mL-1 (P < 0.001). Erythroid and myeloid progenitor precursor cells showed a steep and significant increase after 18 and 24 months of therapy (erythroid: from 10.7 +/- 3.5 to 261.4 +/- 79.8, P < 0.02, after 18 months and to 276.8 +/- 149.8 x 10(5) mononuclear cell colonies, P < 0.03, after 24 months; granulocyte-macrophage colony-forming units: from 39.7 +/- 9.8 to 316.9 +/- 124.6, P < 0.002, after 18 months and to 366 +/- 188.7 x 10(5) mononuclear cell colonies, P < 0.03, after 24 months), whereas the peripheral red and white blood cells exhibited only minimal non-significant changes. The principal regulators of erythropoiesis, such as erythropoietin, and parameters reflecting erythropoiesis in the peripheral blood, such as reticulocytes, remained almost unchanged throughout the whole study period. We therefore conclude that patients with GH deficiency do not have anaemia, but have haematopoietic precursor cells in the lower normal range, and that GH substitution therapy over a period of 24 months has a marked effect on erythroid and myeloid progenitor precursor cells but only negligible effects on peripheral blood cells in GH-deficient adults.

Immunofluorescence analysis of antisense oligodeoxynucleotide-mediated 'knock-down' of the mouse delta opioid receptor in vitro and in vivo

We have previously used antisense oligodeoxynucleotides (ODN) to the cloned delta opioid receptor (DOR) to inhibit the antinociceptive response to spinally administered delta opioid receptor selective agonists in mice. Here we have examined the effect of DOR antisense ODN treatment on the level of DOR expressed in NG 108-15 cells and the spinal cord, through immuno-fluorescence microscopy, to determine the efficiency and selectivity of the antisense ODN-mediated "knock-down' of the DOR in these tissues. Antisense ODN, but not mismatch control, treatment resulted in a significant reduction in DOR immunoreactivity (-ir) in NG 108-15 cells and spinal cord. Thus, the inhibition of antinociceptive response to intrathecal delta selective agonists by DOR antisense ODN correlates with the loss of DOR-ir in the superficial layers of the dorsal horn of the spinal cord.

Differential distribution of two ATP-gated channels (P2X receptors) determined by immunocytochemistry

Several P2X receptor subunits were recently cloned; of these, one was cloned from the rat vas deferens (P2X1) and another from pheochromocytoma (PC12) cells differentiated with nerve growth factor (P2X2). Peptides corresponding to the C-terminal portions of the predicted receptor proteins (P2X1 391-399 and P2X2 460-472) were used to generate antisera in rabbits. The specificities of antisera were determined by staining human embryonic kidney cells stably transfected with either P2X1 or P2X2 receptors and by absorption controls with the cognate peptides. In the vas deferens and the ileal submucosa, P2X1 immunoreactivity (ir) was restricted to smooth muscle, whereas P2X2-ir was restricted to neurons and their processes. Chromaffin cells of the adrenal medulla and PC12 cells contained both P2X1- and P2X2-ir. P2X1-ir was also found in smooth muscle cells of the bladder, cardiac myocytes, and nerve fibers and terminals in the superficial dorsal horn of the spinal cord. In contrast, P2X2-ir was observed in scattered cells of the anterior pituitary, neurons in the hypothalamic arcuate and paraventricular nuclei, and catecholaminergic neurons in the olfactory bulb, the substantia nigra, ventral tegmental area, and locus coeruleus. A plexus of nerve fibers and terminals in the nucleus of the solitary tract contained P2X2-ir. This staining disappeared after nodose ganglionectomy, consistent with a presynaptic function. The location of the P2X1 subunit in smooth muscle is consistent with its role as a postjunctional receptor in autonomic transmission, while in neurons, these receptors appear in both postsynaptic and presynaptic locations.

Orphanin FQ/nociceptin-immunoreactive nerve fibers parallel those containing endogenous opioids in rat spinal cord

Antisera were developed that specifically recognize orphanin FQ/nociceptin, the 17 amino acid peptide reported to be the endogenous ligand for the orphan opioid receptor. Immunocytochemical localizations in rat spinal cord demonstrated that orphanin FQ /nociceptin-immunoreactivity (-ir) was abundant in superficial dorsal horn, lateral spinal nucleus and the region dorsal to the central canal, areas that also exhibit prominent enkephalin-and dynorphin-ir. Orphanin FQ/nociceptin-ir was not affected by dorsal rhizotomy, indicating that in spinal cord the peptide is produced by central rather than primary afferent neurons. thus, the distribution of orphanin FQ/nociceptin-ir appeared in neuronal circuits that parallel those containing enkephalin- and dynorphin-ir, with only modest co-existence of these peptides.

Anterior pituitary function in patients with newly diagnosed rheumatoid arthritis

Hormonal dysfunction involving the hypothalamic-pituitary-adrenal (HPA) axis, prolactin (PRL) secretion and sex hormone status has been supposed to contribute to the development or persistence of rheumatoid arthritis (RA). In addition, a reduced number of glucocorticoid receptors on circulating lymphocytes has been found in patients with RA. However, so far most studies have been performed in pre-treated patients. A combined test for total anterior pituitary reserve was performed in 10 patients with newly diagnosed untreated RA. Before and after stimulation with the respective hypothalamic releasing hormones, RA patients showed no difference in plasma concentrations of adrenocorticotrophic hormone (ACTH), cortisol, prolactin (PRL) and thyroid-stimulating hormone (TSH) when compared to healthy controls. In contrast, the growth hormone (GH) response to growth hormone-releasing hormone (GHRH) was blunted in RA patients. The hypothalamic-pituitary-thyroid/gonadal and adrenal axes seem to be unaltered in RA. However, if one considers the presence of chronic inflammation, normal plasma ACTH and cortisol concentrations must be considered as inappropriately low. The observed blunted GH release could be mediated by cytokines (e.g. IL-1), which are known to be elevated in RA.

The effects of prolonged substitution of recombinant human growth hormone on renal functional reserve in growth hormone-deficient adults

Twelve growth hormone (GH)-deficient adults with normal renal function were recruited for a 6-month, double-blind, placebo-controlled study on the effects of prolonged recombinant human growth hormone (rhGH) substitution therapy on renal functional parameters. RhGH was administered at a dose 0.125 IU/kg per week sc the first 4 wk and 0.25 IU/kg per week thereafter. At baseline and after 6 months of therapy, GFR and RPF were measured by the use of iothalamate and para- aminohippurate clearance techniques before and after an intravenous infusion of amino acids (AA) to determine the renal functional reserve capacity (RFRC). At baseline, GFR and RPF were similar in the GH-deficient patients and a group of normal, healthy controls (GFR, 117 +/- 10 mL/min; RPF, 567 +/- 57 mL/min, and filtration fraction, 22 +/- 1.6% in the patient group and GFR, 117 +/- 10 mL/min; RPF, 509 +/- 54 mL/min; and filtration fraction, 24 +/- 1.3% in the control group). GFR increased significantly in the control and patient group after AA infusion; the RFRC, however, was significantly larger in healthy individuals (GFR post-AA infusion, 141 +/- 10 mL in GH-deficient patients and 182 +/- 20 mL/min in controls). Thereafter, six patients received placebo therapy for 6 months and GFR as well as RFRC remained constant (GFR, 107 +/- 9 and 106 +/- 12 mL/min before AA infusion and 132 +/- 14 and 134 +/- 5 mL/min after AA infusion at baseline and after 6 months, respectively). Four patients of the placebo group then continued with rhGH therapy for another 6 months. They and six patients who had rhGH therapy from the beginning form the rhGH treatment study group. During rhGH treatment, plasma insulin-like growth factor activity increased significantly from 93 +/- 17 to 229 +/- 23 ng/mL. Baseline GFR and RPF as well as RFRC were unaltered by the 6 months of rhGH replacement therapy (basal GFR, 124 +/- 7 mL/min before and 123 +/- 9 mL/min after 6 months of rhGH therapy; GFR after AA infusion, 145 +/- 9 mL/min at baseline and 144 +/- 8 mL/min after 6 months of therapy). Kidney size as evaluated by ultrasonography was normal at baseline when compared with that in age- and sex-matched controls (10.3 +/- 0.2 versus 9.9 +/- 0.1 cm) and was unchanged after 6 months of therapy (10.3 +/- 0.3 cm). It was concluded from this study that rhGH substitution for 6 months at a dose of 0.25 IU/kg per week in GH-deficient patients with normal renal function has no adverse functional effects on the kidney.

The kappa-opioid receptor is primarily postsynaptic: combined immunohistochemical localization of the receptor and endogenous opioids

Antisera were raised against a synthetic peptide corresponding to the carboxyl terminus of the kappa-opioid receptor (KOR1). Specificity of the antisera was verified by staining of COS-7 cells transfected with KOR1 and epitope-tagged KOR1 cDNAs, by recognition by the antisera of proteins on Western blots of both transfected cells and brain tissue, by the absence of staining of both brain tissue and transfected cells after preabsorption of the antisera with the cognate peptide, and on the strong correlation between the distribution of KOR1 immunoreactivity and that of earlier ligand binding and in situ hybridization studies. Results indicate that KOR1 in neurons is targeted into both the axonal and somatodendritic compartments, but the majority of immunostaining was seen in the somatodendritic compartment. In sections from rat and guinea pig brain, prominent KOR1 staining was seen in the ventral forebrain, hypothalamus, thalamus, posterior pituitary, and midbrain. While the staining pattern was similar in both species, distinct differences were also observed. The distribution of preprodynorphin and KOR1 immunoreactivity was complementary in many brain regions, suggesting that KOR1 is poised to mediate the physiological actions of dynorphin. However, the distribution of KOR1 and enkephalin immunoreactivity was complementary in some regions as well. These results suggest that the KOR1 protein is primarily, but not exclusively, deployed to postsynaptic membranes where it mediates the effects of products of preprodynorphin and possibly preproenkephalin.

Distribution of neuropeptide receptors. New views of peptidergic neurotransmission made possible by antibodies to opioid receptors

The cloning of receptors for neuropeptides made possible studies that identified the neurons that utilize these receptors. In situ hybridization can detect transcripts that encode receptors and thereby identify the cells responsible for their expression, whereas immunocytochemistry enables one to determine the region of the plasma membrane where the receptor is located. We produced antibodies to portions of the predicted amino acid sequences of delta, mu, and kappa opioid receptors and used them in combination with antibodies to a variety of neurotransmitters in multicolor immunofluorescence studies visualized by confocal microscopy. Several findings are notable: First, the cloned delta opioid receptor appears to be distributed primarily in axons, and therefore most likely functions in a presynaptic manner. Second, the cloned mu and kappa opioid receptors are found associated with neuronal plasma membranes of dendrites and cell bodies and therefore most likely function in a postsynaptic manner. However, in certain, discrete populations of neurons, mu and kappa opioid receptors appear to be distributed in axons. Third, enkephalin-containing terminals are often found in close proximity (although not necessarily synaptically linked) to membranes containing either the delta or mu opioid receptors, whereas dynorphin-containing terminals are often found in proximity to kappa opioid receptors. Finally, a substantial mismatch between opioid receptors and their endogenous ligands was observed in some brain regions. However, this mismatch was characterized by complementary zones of receptor and ligand, suggesting underlying principles of organization that underlie long-distance, nonsynaptic neurotransmission.

Distribution and targeting of a mu-opioid receptor (MOR1) in brain and spinal cord

Opioid receptors regulate neuronal activity by both pre- and postsynaptic mechanisms. We recently reported that the cloned delta-opioid receptor (DOR1) is primarily targeted to axons, suggesting a presynaptic role. In the present study we have studied the distribution and targeting of another opioid receptor, the mu-opioid receptor (MOR1), by raising anti-peptide antisera to the C-terminal peptide of MOR1. The specificity of the antisera was determined by analysis of transfected cells, Western blots, and immunoisolation studies. Immunohistochemistry showed that MOR1 immunoreactivity was enriched in many brain areas including cerebral cortex, striatum, hippocampus, locus coeruleus, and the superficial laminae of the dorsal horn. Moreover, MOR1-expressing neurons seem to target this receptor preferentially to their somatodendritic domain as determined by double-labeling experiments with MAP2. However, discrete populations of neurons target MOR1 to their axons, including some primary afferent neurons that express DOR1. In many regions enkephalin-containing axons were complementary to MOR1, suggesting by their proximity that enkephalins may be physiologically relevant ligands for this receptor. Thus, these results provide a morphological basis for understanding pre- and postsynaptic functions mediated by MOR1.

delta-Opioid receptor immunoreactivity: distribution in brainstem and spinal cord, and relationship to biogenic amines and enkephalin

We have recently developed antisera which recognize epitopes of the cloned delta-opioid receptor (DOR; Dado et al., 1993). In the present report we have further characterized these antisera, and raised additional antisera in rats. We used these antisera to determine the distribution of DOR-like immunoreactivity (-Ll) in rat spinal cord and brainstem in relation to serotoninergic, noradrenergic, and enkephalinergic neurons. We found DOR-Ll in fibers and varicosities distributed throughout the spinal cord gray matter, with highest densities in the superficial dorsal horn, in autonomic regions, around the central canal as well as in the ventral horn motor nuclei. In the brainstem a dense innervation of DOR-immunoreactive (-IR) fibers was found in several nuclei such as spinal trigeminal nuclei, midline raphe nuclei, parabrachial nuclei, periaqueductal gray matter (PAG), interpeduncular nucleus, ans substantia nigra. A group of DOR-positive cells was seen in the laterodorsal tegmental nucleus. In addition, a few DOR-IR cell bodies were demonstrated in the parabrachial nuclei, interpeduncular nucleus, PAG, and superior and inferior colliculi as well as around the central canal in the spinal cord. All DOR-positive cells showed a punctuate staining pattern within the cytoplasm of the cell body and in primary dendrites. No plasma membrane staining of cells or dendrites could be demonstrated using the DOR antisera. Double-labeling experiments for DOR and 5-hydroxytryptamine (5HT, serotonin) revealed that some 5HT-IR neurons in the raphe complex were surrounded by DOR-IR fibers. In the spinal cord a high degree of coexistence was found between DOR and 5HT in nerve fibers and varicosities in the neuropil around the motoneurons and in lamina V of the dorsal horn. In autonomic regions of the spinal cord, a low degree of colocalization was seen between DOR and 5HT; in the superficial dorsal horn no coexistence was found. Tyrosine hydroxylase (TH)-positive neurons in the brainstem (in the A5 area, locus coeruleus, and A7 area) were apposed by DOR-positive fibers. However, no coexistence could be seen between DOR and TH in any part of the spinal cord. A close relation, but no coexistence, was observed between DOR- and enkephalin (ENK)-IR fibers in the spinal cord ventral horn; in the intermediolateral nucleus a low degree of colocalization was observed. Thus, a delta-opioid receptor may affect the activity of descending serotoninergic and noradrenergic neurons by means of modulating the release of neurotransmitters from afferents to these neurons.(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of elevated growth hormone concentrations on the phenotype and functions of human lymphocytes and natural killer cells

Over the past decades, strong evidence has accumulated that growth hormone (GH) has immunostimulatory properties. Therefore, an investigation was conducted on 10 acromegalic patients and 9 age- and sex-matched healthy controls to determine whether plasma GH concentrations correlate with changes in several immune parameters, including serum concentrations of immunoglobulins, lymphocyte subsets, lymphocyte transformation with phytohemagglutinin (PHA), natural killer (NK) cell activity as well as phagocytic and metabolic burst activity. While NK cell activity, serum concentrations of immunoglobulins (IgG, IgM, IgA) and metabolic burst activity were within the normal range in both groups, a significantly enhanced phagocytic activity was observed in the acromegalic patients. Surface markers on T lymphocytes (CD3, CD4, CD8), B lymphocytes (CD19) and NK cells (CD16/56) were normal in both groups; however, in the acromegalic subjects, CD4+ and CD8+ cells showed a significant higher expression of transferrin receptors (CD71), indicating enhanced T-cell activity. The lymphocyte transformation response to PHA at the highest concentration tested showed a tendency to be elevated in acromegalics; however, the difference failed to be significant. Long-lasting and pronounced elevation of GH in acromegaly induces significantly enhanced phagocytic activity, but only negligible changes in most patients in lymphocyte phenotype and in the lymphocyte response to PHA.

Iodine-123-IBZM-SPECT: studies in 15 patients with pituitary tumors

Single photon emission computerized tomography (SPECT) using the Iodine 123 labeled dopamine D2 receptor antagonist S(-)Iodobenzamide [S (-)IBZM] was performed in 15 patients with pituitary tumors. Among them there were five prolactinoma patients with macroadenoma and two acromegalic patients with macroadenoma. Specific binding in the area of the adenoma was only observed in one subject, a macroprolactinoma patient, who was responsive to dopaminergic treatment. None of the other patients, among them one macroprolactinoma patient responsive to dopaminergic treatment showed specific binding in the area of the tumor. IBZM-binding in the striatum was found to be significantly lower in the group of pituitary tumor patients as compared to controls. The results show that D2 receptors in pituitary adenomas can be visualized using SPECT. However, the sensitivity of IBZM-SPECT appears to be too poor to visualize PRL- and GH- secreting macroadenomas in general.

Laser angioplasty: results of a prospective, multicenter study at 3-year follow-up

A prospective multicenter trial was initiated to evaluate the efficacy and safety of laser angioplasty. Laser recanalization was performed in 338 patients with arteriosclerotic femoropopliteal artery occlusions (average length, 8.5 cm). Neodymium-yttrium-aluminum-garnet lasers were used in combination with sapphire probe catheters. The initial recanalization rate was 85%. Complications were observed in 14% of the patients. Emergency surgery was required in 1.5%. The cumulative long-term patency rate of the successfully recanalized arteries was 80%, 70%, 62%, and 57% at 6 months, 1 year, and 2 and 3 years, respectively. The patency rates were not affected by the length of the occlusion and the long-term medication (platelet inhibition vs anticoagulation), but patients with a normal runoff had significantly better patency rates than those with reduced runoff (63% vs 52%, P less than .01). The study has shown that laser-assisted angioplasty is safe and at least as effective as conventional angioplasty.

[Femoropopliteal laser recanalization--a multicenter study]

Laser-assisted angioplasty was performed in four different hospital centers, following the same treatment protocol and using an Nd-YAG laser with a sapphire-probe catheter. The initial recanalization rate of 259 femoro-popliteal occlusions with a mean length of 7.5 cm was 84%. Dissections or perforations were observed in 10%. An emergency surgical intervention was required in 1.1%. The long-term patency rate of the successfully recanalized arteries was 74% after 2 years. The cumulative cure rate of all 259 patients was 62%.

[A case of prepuberty periodontitis--a classification based on laboratory results]

The rare entity of periodontitis in a 4 1/2-year old child and subsequent changes over a 4-year follow-up period will be presented. Various examinations (among other immunological tests, biochemical differentiation of dermal fibroblasts, and ultrastructural skin biopsies) were made to identify whether this was a case of genuine prepuberty periodontitis or of periodontitis secondary to a general disease. On the basis of the results the case was diagnosed as Ehlers-Danlos Disease Type VIII, although at the same time signs of impaired granulocyte function were observed.

N-hydroxy-N-arylacetamides. V. Differences in the mechanism of haemoglobin oxidation in vitro by N-hydroxy-4-chloroacetanilide and N-hydroxy-4-chloroaniline

1. Autoxidation of N-hydroxy-4-chloroaniline(I) in buffer pH 7.4 was rapid and yielded 4,4'-azoxybischlorobenzene, 4-chloronitrosobenzene, 4-chloronitrobenzene, and 4-chlorophenyl nitroxide. In contrast, autoxidation of N-hydroxy-4-chloroacetanilide(II) was very slow, since in ether and water 78 and 92%, respectively, had decomposed in six months. 2. Haemoglobin(HbO2)-catalysed autoxidation of (I) occurred at a molar ratio of haemoglobin-Fe2+ to (I) of less than 0.25 and was accompanied by ferrihaemoglobin(HbFe3+)-formation and oxygen consumption. Coupled oxidation of HbO2 with (I) occurred at a molar ratio of greater than 0.2 and was accompanied by liberation of oxygen and the formation of HbFe3+, haemoglobin-4-chloronitrosobenzene complex, HbO2, desoxyhaemoglobin, 4-chloronitrosobenzene, 4-chloronitrobenzene, 4-chloroaniline, 4,4'-azoxybischlorobenzene, and 4-chlorophenyl nitroxide. At an equimolar ratio of 10(-3) M haemoglobin-Fe2+ to (I), 96% HbO2 was converted into HbFe3+ (50%) and haemoglobin-4-chloronitrosobenzene complex in the initial fast phase of the reaction, but only 34% of the bound oxygen was liberated, the rest was sequentially reduced to water. (I) completely disappeared, and 4-chloronitrosobenzene was the major metabolite, mainly bound to haemoglobin. 3. Chemical oxidation of (II) by PbO2 in benzene produced acetyl 4-chlorophenyl nitroxide, whose spontaneous decomposition gave 38% 4-chloronitrosobenzene, 33% N-acetoxy-4-chloroacetanilide, 10% 4-chloroacetanilide, and 8% 4-chloronitrobenzene. Its spontaneous decomposition in water also followed second order kinetics, K = 350 l mol-1 sec-1 and yielded N-(2-acetylamino-5-chlorophenyl)-p-benzo-quinoneimine-N-oxide in addition. 4. In the coupled oxidation of 10(-3) M haemoglobin-Fe2+ with 10(-3) M (II), 75% HbFe3+ was formed after 1 h, but only one third of the equivalent of oxygen was released, and two thirds were reduced to water. Concentration of (II) decreased by 5% only, indicating that one mol of (II) had catalysed the oxidation of 15 equivalents of haemoglobin-Fe2+. The identity of the product pattern formed with HbO2 with that produced by chemical one-electron oxidation indicated that oxygen bound to haemoglobin also functions as an acceptor for electrons from (II) as from (I), but the different redox potentials can explain why the secondary aromatic nitroxide was catalytically active and the primary nitroxide was not.

Spinal traumas: some postoperative complications in experimental animals

Animals with severe spinal traumas show paraplegic syndrome and various somatic and autonomic dysfunctions. Of the various dysfunctions those related to hypothermia, bladder problems, and autophagia are of serious nature. The condition of animals with these complications deteriorates rapidly, and the animals are sacrificed for histological and pathological analyses. The findings show that the postoperative complications are related to the degree of severity of the trauma, and that 50-80% animals are lost due to these complications. Most of these animals are lost during the first two weeks after surgery, and the remaining at later stages. Transplantation of neural tissue at the site of lesion does not ameliorate these postoperative complications and improve the survival rate of the animals.

Specificity of ganglioside binding to rat macrophages

The binding specificity of rat alveolar macrophages (AM phi) for sheep erythrocytes (E) coated with gangliosides GM1, GM2, GM3, GD1a, GD1b or GT1b was analyzed in a rosette assay by studying the inhibitory effect of gangliosides, various carbohydrates, IgG, C3b-like C3, and fibronectin in this assay. The uptake of gangliosides by E was calculated from radioactivity measurements using 3H-labeled gangliosides. The different gangliosides were taken up by E at 37 degrees C to a similar extent. Uptake of 3H-labeled GM2 correlated linearly to its concn in the incubation medium. Erythrocytes pretreated with the same molar concn of GM2, GD1a, GD1b or GT1b were bound to AM phi to the same degree reaching a maximum of about 90% rosette forming cells. A mean of 17.8% AM phi-bound GM3-coated E. Treatment of E with asialo-GM2 (GA2) or GM1 did not induce significant rosette formation. A dose-dependent inhibition of rosette formation was observed when AM phi were preincubated at 0 degree C with GM2, GM3, GD1a, GD1b or GT1b, but not with GM1 or GA2 Of the tested carbohydrates, sialyl-lactose had a strong inhibitory effect, while lactose was completely ineffective. N-acetyl-neuraminic acid, N-glycolyl-neuraminic acid and N-acetyl-galactosamine were slightly inhibitory. A series of other carbohydrates including highly negatively charged compounds, as well as fibronectin, IgG or C3b-like C3 did not show significant inhibition. Our data indicate the expression of a receptor on rat AM phi recognizing carbohydrates containing sialic acid at or near the non-reducing terminus.

Ganglioside receptor of rat macrophages. Modulation by enzyme treatment and evidence for its protein nature

Previous experiments have shown that rat macrophages (M phi) bind specifically sheep erythrocytes (E) coated with various gangliosides (EG). To study the nature of this receptor-like structure, M phi were treated with proteinases, and their capacity to bind EG and/or E was analyzed in a rosette assay. Within 10 min of incubation with appropriate doses of enzymes, a clear enhancement of EG-binding activity was observed. In addition, enzyme-treated M phi bound uncoated E. Inhibition studies with gangliosides and carbohydrates, and enzyme treatment of E showed that this binding is mediated by the same M phi ganglioside receptor. The kinetics of the modulation of binding activity of M phi during trypsin treatment were similar for both E and EG. At optimal enzyme concentration a triphasic effect was noted. Enhancement of EG-binding and appearance of E-binding activity after 10-20 min was followed by a reduction of rosette-forming cells (RFC) with a minimum at about 1 hr and then by an increase of both E-RFC or EG-RFC up to 5 hr. Simultaneous incubation of M phi with trypsin and cycloheximide abrogated the second rise of binding activity and abolished binding on prolonged incubation. When these cells were washed and further incubated in fresh medium, they regained their initial E- and EG-binding capacity after 4-5 hr incubation. Taken together, these results are consistent with the idea that rat M phi bear a ganglioside receptor-like structure which seems to be a membrane protein and which is modulated by enzyme treatment.

Antigenic heterogeneity of rat macrophages. A monoclonal antibody reacting only with alveolar but not with other types of macrophages

Hybridoma antibodies were produced by fusing spleen cells from mice immunized with rat alveolar macrophages (AM) with P3 x 63Ag8/653 myeloma cells. Some of the hybridomas were processed to achieve monoclonality. Reactivity was tested in an indirect membrane immunofluorescence assay. One of the monoclonal antibodies, called VEP6 antibody, reacted with rat AM but not with peritoneal or splenic macrophages and not with peripheral blood monocytes of this species. It was also unreactive with cells from thymus, bone marrow, non-adherent spleen cells, granulocytes and erythrocytes, but it reacted with thrombocytes. Corynebacterium parvum activated AM were slightly less reactive then 'resident' AM, as determined in a fluorescence activated cell sorter. The VEP6 antigen was studied in polyacrylamide gel electrophoresis after immunoprecipitation from 125I-surface-labelled-macrophage NP40-lysates. Four specific radioactive bands were seen in the precipitates corresponding to molecular weights of 31, 33, 35 and 37,000. A slurred band was seen in this molecular weight range when immunoprecipitates of surface labelled thrombocytes were analysed. This study confirms the heterogeneity of macrophages by showing that certain antigens may be expressed only on a subpopulation of macrophages.

A ganglioside-dependent cellular binding mechanism in rat macrophages

A rosetting assay was performed with rat alveolar and peritoneal macrophages and sheep red blood cells (SRBC) treated with gangliosides. SRBC incubated with GM2, GD1a, and a mixture of bovine brain gangliosides (BBG) showed binding to rat macrophages. The extent of binding was dependent on the concentration of gangliosides. Binding induced by GM2 was stronger than that induced GD1a and BBG. GM1 and GA2 did not induce rosette formation. Inhibition studies with gangliosides, sialyllactose, lactose, and neuraminic acid suggested that the macrophage binding site recognizes neuraminic acid in conjunction with neighboring carbohydrates showing highest affinity for GM2. Sodium azide, sodium fluoride, ethylenediaminetetraacetate, cytochalasin B, and colchicine did not inhibit rosette formation. The percentage of peritoneal macrophages binding ganglioside-treated SRBC was lower than that of alveolar macrophages. Proteose-peptone-stimulated peritoneal macrophages, however, showed an increase of rosette formation. Around 30% of adherent spleen cells also had binding activity for GM2-treated SRBC. Peripheral blood mononuclear cells did not bind ganglioside-treated SRBC. Phagocytosis of GM2-treated SRBC attached to alveolar macrophages could not be observed. It is suggested that macrophages may express recognition sites for certain gangliosides that might be important in cell-cell interaction.

A ganglioside-dependent cellular binding mechanism in rat macrophages

A rosetting assay was performed with rat alveolar and peritoneal macrophages and sheep red blood cells (SRBC) treated with gangliosides. SRBC incubated with GM2, GD1a, and a mixture of bovine brain gangliosides (BBG) showed binding to rat macrophages. The extent of binding was dependent on the concentration of gangliosides. Binding induced by GM2 was stronger than that induced GD1a and BBG. GM1 and GA2 did not induce rosette formation. Inhibition studies with gangliosides, sialyllactose, lactose, and neuraminic acid suggested that the macrophage binding site recognizes neuraminic acid in conjunction with neighboring carbohydrates showing highest affinity for GM2. Sodium azide, sodium fluoride, ethylenediaminetetraacetate, cytochalasin B, and colchicine did not inhibit rosette formation. The percentage of peritoneal macrophages binding ganglioside-treated SRBC was lower than that of alveolar macrophages. Proteose-peptone-stimulated peritoneal macrophages, however, showed an increase of rosette formation. Around 30% of adherent spleen cells also had binding activity for GM2-treated SRBC. Peripheral blood mononuclear cells did not bind ganglioside-treated SRBC. Phagocytosis of GM2-treated SRBC attached to alveolar macrophages could not be observed. It is suggested that macrophages may express recognition sites for certain gangliosides that might be important in cell-cell interaction.

The human thyrocervical trunk: configuration and variability reinvestigated

Reinvestigation of the configuration of the human thyrocervical trunk revealed, that in the presently investigated specimens the dorsal scapular artery is a direct branch of the subclavian artery in approximately 75% of the cases, whereas in the remaining 25% it is derived from the thyrocervical trunk, either directly or via the transverse cervical artery (Nomina anatomica 1977). The internal thoracic artery participates in the thyrocervical trunk in more than 10% of the observed cases. Thus, both dorsal scapular and internal thoracic artery have to be considered as facultative branches of the thyrocervical trunk. According to our results, the subclavian artery must be considered as the most common site of origin of the dorsal scapular artery. This vessel may be replaced by another artery in about one fourth of the cases. A survey of studies on the origin of the dorsal scapular artery clearly demonstrates that it is not warranted to give an overall numerical proportion for the main modes of branching. As yet no satisfactory explanation for the high degree of variability of these subclavian branches has been given. Especially the widely held notion of differences related to race, which is based on Adachi's (1928) work, has turned out to be invalid. Interpretation of variability may rather be based, as a general concept, on the late acquisition of a thyrocervical trunk in phylogeny as well as in ontogeny.