A comparison of the effects of adrenaline and noradrenaline on human heart: the role of beta 1- and beta 2-adrenoceptors in the stimulation of adenylate cyclase and contractile force

The stimulant effects of adrenaline and noradrenaline on contractile force and adenylate cyclase, mediated through beta 1 and beta 2-adrenoceptors, are analysed in isolated atrial and ventricular myocardium of man. The tissues were obtained from patients without advanced heart failure undergoing heart surgery. Usually, both adrenaline and noradrenaline stimulated adenylate cyclase predominantly through ventricular and atrial beta 2-adrenoceptors. Because the relative density of beta 2-adrenoceptors is usually smaller than that of beta 1-adrenoceptors, stimulation of one beta 2-adrenoceptor leads to the production of up to 10 times more cyclic AMP molecules than does stimulation of one beta 1-adrenoceptor. Adrenaline and noradrenaline maximally enhance contractile force through both atrial and ventricular beta 1-adrenoceptors. Adrenaline can also maximally enhance contractile force through atrial beta 2-adrenoceptors. In the ventricle, adrenaline increases force via beta 2-adrenoceptors by up to 60% of its maximal beta 1 response. Noradrenaline can increase atrial and ventricular contractile force through beta 2-adrenoceptors but only at high concentrations. Unexpectedly, in atria from patients treated with the beta 1-selective antagonist atenolol, contractile responses to adrenaline are markedly and selectively augmented through activation of beta 2-adrenoceptors. In atria from atenolol-treated patients equi-inotropic concentrations of adrenaline and noradrenaline acting through beta 2 and beta 1-adrenoceptors, respectively, cause similar increases of cyclic AMP and of cyclic AMP-dependent protein kinase activity.

Partial purification and some properties of rat brain inositol 1,4,5-trisphosphate 3-kinase

An enzyme which catalyses the ATP-dependent phosphorylation of inositol 1,4,5-trisphosphate [Ins(1,4,5)P3] was purified approx. 180-fold from rat brain cytosol by (NH4)2SO4 precipitation, chromatography through hydroxyapatite, anion-exchange fast protein liquid chromatography and gel-filtration chromatography. Gel filtration on Sepharose 4B CL gives an Mr of 200 x 10(3) for the native enzyme. The inositol tetrakisphosphate (InsP4) produced by the enzyme has the chromatographic, chemical and metabolic properties of Ins(1,3,4,5)P4. Ins(1,4,5)P3 3-kinase displays simple Michaelis-Menten kinetics for both its substrates, having Km values of 460 microM and 0.44 microM for ATP and Ins(1,4,5)P3 respectively. When many of the inositol phosphates known to occur in cells were tested, only Ins(1,4,5)P3 was a substrate for the enzyme; the 2,4,5-trisphosphate was not phosphorylated. Inositol 4,5-bisphosphate and glycerophosphoinositol 4,5-bisphosphate were phosphorylated much more slowly than Ins(1,4,5)P3. CTP, GTP and adenosine 5'-[gamma-thio]triphosphate were unable to substitute for ATP. When assayed under conditions of first-order kinetics, Ins(1,4,5)P3 kinase activity decreased by about 40% as the [Ca2+] was increased over the physiologically relevant range. This effect was insensitive to the presence of calmodulin and appeared to be the result of an increase in the Km of the enzyme for Ins(1,4,5)P3. Preincubation with ATP and the purified catalytic subunit of cyclic AMP-dependent protein kinase did not affect the rate of phosphorylation of Ins(1,4,5)P3 when the enzyme was assayed at saturating concentrations of Ins(1,4,5)P3 or at concentrations close to its Km for this substrate.

Differential effects of proteolysis and protein modification on the activities of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase

Rat liver 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase catalyzes exchange reactions between ADP and ATP and between fructose-6-P and fructose-2,6-P2 at histidyl residues. Limited proteolysis of the enzyme with thermolysin yielded an enzyme core with a subunit molecular weight of 35,000-38,000. This enzyme core had no kinase activity and a 2-fold activated bisphosphatase activity whose sensitivity to the product inhibitor fructose-6-P was unchanged. The thermolysin-treated enzyme also did not catalyze the fructose-6-P/fructose-2,6-P2 exchange reaction but did catalyze the ADP/ATP exchange. These results suggest that 1) the enzyme's reactions may be catalyzed at two active sites, 2) there are at least two fructose-6-P binding sites, 3) the fructose-6-P/fructose-2,6-P2 exchange is catalyzed only at the kinase site, and 4) inactivation of the exchange and kinase reactions by thermolysin digestion is due to the loss of the fructose-6-P binding site of the kinase. Also consistent with these conclusions was the finding that oxidation of the enzyme with ascorbate/Fe3+ or H2O2 resulted in complete loss of the kinase activity as well as the fructose-6-P/fructose-2,6-P2 exchange but did not affect the bisphosphatase activity or the ADP/ATP exchange. Dithiothreitol could completely reactivate the ascorbate/Fe3+-inactivated enzyme, suggesting that oxidation occurred at a sulfhydryl group(s) essential for fructose-6-P binding in the kinase reaction. In addition, the kinase and fructose-6-P/fructose-2,6-P2 exchange reactions were more sensitive to inactivation by diethylpyrocarbonate than was the bisphosphatase. The different responses of the kinase and bisphosphatase reactions to the action of these various protein-modifying agents and to thermolysin digestion support the existence of a separate site for each reaction and an essential role for sulfhydryl groups at the sugar-phosphate-binding site(s) of the kinase.

Amino acid sequence of the phosphorylation site of rat liver 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase

6-Phosphofructo-2-kinase/fructose-2,6-bisphosphatase from rat liver was phosphorylated by cyclic AMP-dependent protein kinase and [gamma-32P]ATP. Treatment of the 32P-labeled enzyme with thermolysin removed all of the radioactivity from the enzyme core and produced a single labeled peptide. The phosphopeptide was purified by ion exchange chromatography, gel filtration, and reverse phase high pressure liquid chromatography. The sequence of the 12-amino acid peptide was found to be Val-Leu-Gln-Arg-Arg-Arg-Gly-Ser(P)-Ser-Ile-Pro-Gln. Correlation of the extent of phosphorylation with activity showed that a 50% decrease in the ratio of kinase activity to bisphosphate activity occurred when only 0.25 mol of phosphate was incorporated per mol of enzyme subunit, and maximal changes occurred with 0.7 mol incorporated. The kinetics of cyclic AMP-dependent protein kinase-catalyzed phosphorylation of the native bifunctional enzyme was compared with that of other rat liver protein substrates. The Km for 6-phosphofructo-2-kinase/fructose-2, 6-bisphosphatase (10 microM) was less than that for rat liver pyruvate kinase (39 microM), fructose-1,6-bisphosphatase (222 microM), and 6- phosphofructose -1-kinase (230 microM). Comparison of the initial rate of phosphorylation of a number of protein substrates of the cyclic AMP-dependent protein kinase revealed that only skeletal muscle phosphorylase kinase was phosphorylated more rapidly than the bifunctional enzyme. Skeletal muscle glycogen synthase, heart regulatory subunit of cyclic AMP-dependent protein kinase, and liver pyruvate kinase were phosphorylated at rates nearly equal to that of 6-phosphofructo-2-kinase/fructose-2, 6-bisphosphatase, while phosphorylation of fructose-1,6-bisphosphatase and 6-phosphofructo-1-kinase was barely detectable. Phosphorylation of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase was not catalyzed by any other protein kinase tested. These results are consistent with a primary role of the cyclic AMP-dependent protein kinase in regulation of the enzyme in intact liver.

Improved rabbit brain tumor model amenable to diagnostic radiographic procedures

The VX2 carcinoma was used to create a rabbit brain tumor model. VX2 tumors were chemically dissociated and suspended in liquid medium. Twenty-five microliters of the tumor suspension containing 3 X 10(3), 3 X 10(4), or 3 X 10(5) viable tumor cells were injected through cranial burr holes 6 mm into the right frontoparietal lobes of 17 rabbits. Fifteen of these developed histologically documented nodular intraparenchymal tumors. Tumors were demonstrable with cerebral computed tomographic scans and by cerebral angiography. The feasibility of surgical resection of lesions using the fluorescein staining technique was also demonstrated. This animal brain tumor model is suitable for neuro-oncology research focusing on imaging and therapeutic techniques.

Improved surgical resection of human brain tumors: Part I. A preliminary study

Twenty-three patients underwent craniotomies for brain malignancies. One hundred eleven fluorescein-stained and 75 nonstained tissue biopsies were obtained for histopathological examination using a special arc-lighting system connected to a conventional surgical headlight. Of the 75 nonstained specimens, 71 (94.7%) were negative for tumor and 4 demonstrated the presence of tumor. Ninety-four (84.7%) of the fluorescent tissues obtained were reported as having neoplasia and the remaining 17 showed characteristics consistent with necrotic tissue debris. All stained tissues obtained in this study demonstrated visible fluorescence within neoplastic tissue margins harboring abnormally permeable blood-brain barriers.

Contraction in intact pig aortic strips is not always associated with phosphorylation of myosin light chains

Intact pig aortic strips were incubated in medium containing [32P]P1 and various Ca2+ concentrations. The 32P content of the myosin P-light chain was determined by radioautography after electrophoresis in the presence of sodium dodecyl sulphate. Although treatment of the strips with noradrenaline always caused a rise in tension, this was not necessarily accompanied by increased phosphorylation of the P-light chain. These results indicate that, in aortic smooth muscle, phosphorylation of the P-light chain is not obligatory for contraction.

Comparative biochemical and ultrastructural studies of capillaries from normal humans, normal mice, and human cerebral astrocytomas

Capillaries from cerebral white matter were isolated from normal humans and normal mice and from human astrocytomas (Grades II-IV) to investigate potential biochemical and ultrastructural differences between normal and neoplastic-derived microvessels. Capillaries from Grade III and IV astrocytomas averaged 55-fold higher in the concentration of total protein than capillaries from normal mouse and normal human cerebral tissues. Scanning electron microscopic examination revealed more bifurcations and fewer surface undulations in the capillaries derived from anaplastic astrocytomas than in capillaries derived from normal specimens. Sprouting configurations were detected in the capillaries from anaplastic astrocytomas. They measured 4 to 5 micron in diameter and manifested fewer surface undulations than capillaries from normal human white matter. The results of these preliminary investigations suggest early capillary growth from parent vessels in high-grade and highly vascularized astrocytomas.

Intracranial pressure monitoring in the acute neurologic assessment of multi-injured patients

The trauma victim with a severe closed head injury, who requires general anesthesia for emergency repair of concomitant exigent major injuries, poses a clinical dilemma. During general anesthesia and during the immediate postoperative period, the status of the patient's central nervous system cannot be clinically monitored, and emergency cerebral arteriograms and/or CAT scans are not easily obtained. Under these circumstances, delays in the diagnosis of intracranial blood accumulations frequently occur, and occult cerebral edema often goes untreated. In an attempt to avoid these management problems, we have employed intraoperative intracranial pressure (ICP) monitoring in such patients, using a subarachnoid screw. Following placement of this screw, several clinical courses may occur: 1) The patient maintains a normal pressure; thus a significant mass lesion and/or cerebral edema requiring decompression is unlikely. 2) The patient's ICP is elevated but controlled by medical management. 3) The patient's ICP cannot be controlled below 20 to 25 mm Hg using medical management, and exploratory burr holes are made. 4) If intracranial blood is encountered during placement of the ICP monitor, immediate exploratory craniotomy is indicated.

An association of upper respiratory cancer with exposure to diethyl sulfate

A morbidity and mortality study of workers at an alcohol manufacturing plant which included several weak acid isopropyl alcohol units and a strong acid ethanol unit is described. An excess mortality of upper respiratory cancer was found and associated with work on the strong acid ethanol unit. The strong acid ethanol process used resulted in high concentrations of diethyl sulfate, which has been shown to be carcinogenic in animals, and the unit, which closed on 1975, had significant opportunities for worker exposure to diethyl sulfate. These facts, plus previous reports of excess upper respiratory cancer on strong acid isopropyl alcohol units with similarly high concentrations of the animal carcinogen diisopropyl sulfate, lead to the tentative conclusion that diethyl sulfate was primarily responsible for the ethanol unit cancer cases. In the modern weak acid isopropyl alcohol plants, where only trace amounts of diisopropyl sulfate are present and exposures are much lower, the problems found on the old strong acid units do not exist.

Prolactin suppression of leukocyte chemotaxis in vitro

Leukocyte chemotaxis in vitro was studied for cells from patients with pituitary adenomas. Leukocytes obtained preoperatively from two of three patients with elevated serum prolactin levels demonstrated chemotaxic alterations described in other malignant disease. Statistically significant suppression of chemotaxis occurred in the leukocytes of four of 12 specimens from normal donors at concentrations of 1000 ng/ml, and in four of eight specimens at 2000 ng/ml of prolactin in preincubation media. Thus prolactin concentration may influence the motility of leukocytes. The variable neoplastic behavior of morphologically similar pituitary adenomas may, in part, reflect a neurohormonally altered host response to the presence of these lesions.

Surface topography of normal and neoplastic human anterior pituitary cells maintained in vitro

Pituitary tissues were obtained from 25 patients who underwent surgery for excision of pituitary macroadenomas, selective excision of microadenomas, or removal of a normal gland for palliation of metastatic cancer. Cells thus obtained were maintained in vitro for varying intervals, fixed, and examined by light (phase contrast), microscopy, transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Previous SEM reports indicate that surface topography of in vitro neoplastic cells displays features that may correlate with neoplastic behavior. Cultured normal and pituitary tumor cells did not display these surface differences, with one exception, a prolactin-secreting microadenoma. Characteristic patterns for the cell populations were identified. Certain cell types appeared in all the cultures: 1) large and small granule-containing cells; 2) flat and irregular cells; 31 spindle-shaped cells; and 4) spherical, irregularly surfaced cells. In one case of an endocrine-inactive juvenile pituitary chromophobe adenoma, unique cells were observed. Surface topography did not appear to be of predictive value in determining the neoplastic character of pituitary tumors.

Blood-group antigens and antibodies in human brain-tumor cysts

Cyst fluids from 12 human brain tumors were studied for their blood-group content and compared to autologous saliva, serum, and cerebrospinal fluid (CSF). Lewisa substance, which is a fucolipid, was present in four of 12 cysts studied. Lewisb, which differs from Lewisa by a single fucose, was found in eight of 12 sera and/or saliva and in one CSF specimen; Lewisb substance, however, was not detected in any corresponding cyst fluids. Isohemagglutinins, blood-group antibodies anti-A and/or anti-B, were present in nine of nine cyst fluids studied, were of lower titers as compared to autologous serum, and occurred as either IgG or IgM immunoglobulins. The results further delineate the biochemical requirements necessary for molecular penetration into human brain-tumor cysts.

Hypogammaglobulinemia and Nocardia brain abscesses

The host defense responses to Nocardia asteroides are not known. We have investigated a patient with common variable adult onset hypogammaglobulinemia who developed fatal disseminated nocardiosis. The patient had low levels of serum immunoglobulins; the total lymphocyte count was normal as were the percentages of circulating T and B cells. Transmission electron microscopic studies demonstrated typical N. asteroides within the brain parenchyma and nonspecific inflammatory changes in the central nervous system. The findings suggest that humoral immunity may play a major role in the host defense of patients with this disease.

Neutrophil chemotaxis in cerebral astrocytoma

Neutrophil chemotaxis was evaluated for five patients with a primary intracerebral malignancy. All patients had intratumor cysts and these fluids with corresponding serum and cerebrospinal fluid were tested for their chemotactic ability. The ability of cyst fluid to effect neutrophil chemotaxis was diminished in comparison to serum from either patients or control population. Cyst fluids had lower complement levels than serum and did not have a humoral chemotactic inhibitor. The neutrophils for both the patient and control groups had similar chemotaxis to a given chemotactic stimulus suggesting that this malignancy does not have an accompanying peripheral blood phagocytic cell chemotactic defect. Chemotaxis, the migration of phagocytic cells, is a fundamental requisite for the inflammatory and the immune response.

Immunoproteins in human brain tumor cyst fluids

Quantitation of the concentration of immunoproteins in serum, and cystic fluids from six patients (three with cerebral astrocytoma and three with cerebellar hemangioblastoma) has been determined. The values for total protein, albumin, immunoproteins IgG, IgA, and IgM, and C3C (complement) in cyst fluid more closely correspond to serum than to cerebrospinal fluid values. Values for cyst fluid, cerebrospinal fluid, and serum were determined using albumin ratios in order to compare relative differences between fluids from these three compartments. Our data suggests that: 1) the major protein content of brain tumor cyst fluid is consequential to a transudative process from serum, and 2) that immunoglobulins IgG and IgA are present in higher concentrations in human brain tumor cyst fluids in comparison to IgM concentrations. These studies further question the concept of the brain as an "immunological privileged site", and may be of direct relevance to the investigation of the use of immunotherapeutic modalities as an adjunct after surgical tumor removal.

Topographical anatomy of human cerebral and cerebellar astrocytomas in vitro

This study further characterizes the morphological and in vitro properties of human neoplastic cells derived from one Grade IV cerebral astrocytoma and one Grade III cerebellar astrocytoma. Light microscopic observations performed weekly over a four month period revealed two morphologically indistinguishable cell populations in each of the tumor cultures. Scanning electron microscopy demonstrated the presence of microvilli, blegs, and ruffles on the cell surfaces of both tumors; however, these topographical features were more prominent in the cultures derived from the Grade III cerebellar astrocytoma. Scanning electron microscopy may provide a useful tool for the further morphologic classification of human astrocytomas.