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Biomedical subjects

M Gerber

Publications and source records attributed to M Gerber.

At least 109 records · Page 6Linked to original sources
PubMed1988

Three-dimensional movements of the upper cervical spine.

Knowledge of the normal movements of the occipito-atlanto-axial joint complex is important for evaluating clinical cases that may be potentially unstable. The purpose of this in vitro study was to quantitatively determine three dimensional movements of the occiput-C1 and C1-C2 joints. Ten fresh cadaveric whole cervical spine specimens (occiput to C7) were studied, using well-established techniques to document the movements in flexion, extension, left and right lateral bending, and left and right axial rotation. Pure moments of a maximum of 1.5 N-m were applied incrementally, and three-dimensional movements of the bones were recorded using stereophotogrammetry. Each moment was applied individually and in three load/unload cycles. The motion measurements were made on the third load cycle. Parameters of neutral zone, elastic zone, and range of motion were computed. Neutral zones for flexion/extension, right/left lateral bending, and right/left axial rotation were, respectively: 1.1, 1.5, and 1.6 (occiput-C1); and 3.2, 1.2, and 29.6 degrees (C1-C2). Ranges of motion for flexion, extension, lateral bending (one side), and axial rotation (one side) were, respectively: 3.5, 21.0, 5.5, and 7.2 degrees (occiput-C1 joint) and 11.5, 10.9, 6.7, and 38.9 degrees (C1-C2 joint). The greatest intervertebral motion in the spine was axial rotation at the C1-C2 joint, with the neutral zone constituting 75% of this motion.

Adult↗
PubMed1988

The gene encoding the hydrophobic surfactant protein SP-C is located on 8p and identifies an EcoRI RFLP.

Pulmonary surfactant is composed primarily of phospholipids but also contains three known surfactant-specific proteins. These proteins are important in determining the physical properties of pulmonary surfactant--including its ability to adsorb to an air-liquid interface and its structure--but also appear to influence surfactant metabolism. We have previously assigned two surfactant proteins, SP-A (a 28-36-kDa glycoprotein) and SP-B (an 18-kDa hydrophobic protein), to the short arm of chromosome 10 and to chromosome 2, respectively. We now report that the gene encoding the 5-8 kDa hydrophobic surfactant protein SP-C is located on the short arm of chromosome 8. A cDNA clone encoding the entire protein recognizes a useful EcoRI restriction-site-length polymorphism. Evaluation of congenital syndromes manifesting autosomal abnormalities does not further elucidate the functional role of this protein in promoting normal respiratory physiology.

Animals↗
PubMed1988

Multicenter evaluation of a specific pancreatic isoamylase assay based on a double monoclonal-antibody technique.

Eleven evaluators from nine laboratories in five countries evaluated a new immunoinhibition method for pancreatic isoamylase determination that is as simple to perform as that for total amylase. The precision at low and intermediate activity concentrations was superior, and at high concentrations it equalled that of the wheat-germ inhibitor method. The test was linear to approximately 2000 U/L, depending on the instrumentation used. The percentage salivary isoamylase activities remaining in specimens after reaction with two monoclonal antibodies ranged from 2 to 4.4%. Comparative studies showed good correlation with the wheat-germ inhibitor (r greater than 0.978) and electrophoresis methods (r = 0.920). Hemolysis, lipemia, and bilirubinemia have no effect on results. Interlaboratory studies demonstrated excellent transferability of the method, if instruments are calibrated with the same calibrator. Reference intervals for pancreatic isoamylase are 13 to 64 U/L (25 degrees C), 13 to 83 U/L (30 degrees C), and 17 to 115 U/L (37 degrees C). A clinical evaluation of patients with acute pancreatitis showed that pancreatic isoamylase has a greater clinical sensitivity than total amylase.

Acute Disease↗
PubMed1988

Oxidative phenomena are implicated in human T-cell stimulation.

Phytohaemagglutinin (PHA), phorbol myristate acetate (PMA) and PHA + PMA stimulation of T-enriched peripheral blood lymphocytes (PBL) and the Jurkat malignant T-cell line leads to oxidative-product formation, as evaluated by flow cytofluorometric studies, an increase in K+ flux across the membrane, cGMP production and a depolarization of the cell membrane. Irradiation (20 Gy), which enhances IL-2 synthesis by activated T-enriched PBL and Jurkat cells, also increases oxidative product formation, K+ flux, cGMP production, and induces cell membrane depolarization. Conversely, irradiation does not produce a rise in intracellular free Ca2+, as measured in PHA-stimulated Jurkat cells. PMA is also without effect on intracellular free Ca2+, added before or after PHA stimulation. Thus, except for the rise in intracellular free Ca2+, irradiation and stimulation exert similar effects on some of the events observed in IL-2-producing Jurkat cells, but these effects are not additive. Stimulation and irradiation effects are shown to be additive or synergistic only for cGMP production. It is proposed that irradiation may increase IL-2 synthesis by participating in an additional signal related to the oxidative metabolism of arachidonic acid (AA).

Calcium↗
PubMed1987

Active-site cobalt(II)-substituted horse liver alcohol dehydrogenase: characterization of intermediates in the oxidation and reduction processes as a function of pH.

Substitution of Co(II) for the catalytic site Zn(II) of horse liver alcohol dehydrogenase (LADH) yields an active enzyme derivative, CoIIE, with characteristic Co(II) charge-transfer and d-d electronic transitions that are sensitive to the events which take place during catalysis [Koerber, S. C., MacGibbon, A. K. H., Dietrich, H., Zeppezauer, M., & Dunn, M. F. (1983) Biochemistry 22, 3424-3431]. In this study, UV-visible spectroscopy and rapid-scanning stopped-flow (RSSF) kinetic methods are used to detect and identify intermediates in the LADH catalytic mechanism. In the presence of the inhibitor isobutyramide, the pre-steady-state phase of alcohol (RCH2OH) oxidation at pH above 7 is characterized by the formation and decay of an intermediate with lambda max = 570, 640, and 672 nm for both aromatic and aliphatic alcohols (benzyl alcohol, p-nitrobenzyl alcohol, anisyl alcohol, ethanol, and methanol). By comparison with the spectrum of the stable ternary complex formed with oxidized nicotinamide adenine dinucleotide (NAD+) and 2,2',2''-trifluoroethoxide ion (TFE-), CoIIE(NAD+, TFE-), the intermediate which forms is proposed to be the alkoxide ion (RCH2O-) complex, CoIIE(NAD+, RCH2O-). The timing of reduced nicotinamide adenine dinucleotide (NADH) formation indicates that intermediate decay is limited by the interconversion of ternary complexes, i.e., CoIIE(NAD+, RCH2O-) in equilibrium CoIIE(NADH, RCHO). From competition experiments, we infer that, at pH values below 5, NAD+ and alcohol form a CoIIE(NAD+, RCH2OH) ternary complex. RSSF studies carried out as a function of pH indicate that the apparent pKa values for the ionization of alcohol within the ternary complex, i.e., CoIIE(NAD+, RCH2OH) in equilibrium CoIIE(NAD+, RCH2O-) + H+, fall in the range 5-7.5. Using pyrazole as the dead-end inhibitor, we find that the single-turnover time courses for the reduction of benzaldehyde, p-nitrobenzaldehyde, anisaldehyde, and acetaldehyde at pH above 7 all show evidence for the formation and decay of an intermediate. Via spectral comparisons with CoIIE-(NAD+, TFE-) and with the intermediate formed during alcohol oxidation, we identify the intermediate as the same CoIIE(NAD+, RCH2O-) ternary complex detected during alcohol oxidation.

Alcohol Dehydrogenase↗
PubMed1987

Lipoxygenase inhibitors suppress IL-2 synthesis: relationship with rise of [Ca++]i and the events dependent on protein kinase C activation.

The present study was performed in an attempt to understand the mechanism involved in the inhibition of interleukin 2 (IL-2) synthesis by lipoxygenase (LO) pathway inhibitors. Using the two IL-2-producing lymphoid cell lines, (Jurkat and EL4 cells), we showed first that the inhibitory effect of the phenolic compounds tested (NDGA, BHA and caffeic acid) acted on lymphoid cells themselves and not on eventual monocytic or granulocytic contaminant cells. Secondly, these inhibitors were demonstrated as exerting their effect on two levels: they affected the events controlled by both second messengers implicated in T cell activation, namely rise of intracellular free calcium concentration [( Ca++]i) and protein kinase C (PKC) activation. For this purpose, LO inhibitor effects have been compared: (a) on IL-2 production by the two different lines: Jurkat cells, which need both signals, and EL4 cells, which require only PKC activation for the induction of this production; and (b) on the events induced by the different ways of Jurkat cell activation: PHA (or anti-CD3 monoclonal antibody) versus calcium ionophore. These results are discussed with respect to an eventual involvement of arachidonic acid [AA] derivatives in IL-2 synthesis.

Animals↗
PubMed1987

CT-functional diagnostics of the rotatory instability of upper cervical spine. 1. An experimental study on cadavers.

Twelve specimens of the upper cervical spine were functionally examined by using radiography, cineradiography and computerized tomographic (CT) scan. The range of rotation was measured from CT images after maximal rotations to both sides. The left alar ligament was then cut and the examination repeated. The alar and transverse ligaments could be differentiated on CT images in axial, sagittal, and coronal views. Rotation at occiput-atlas was 4.35 degrees to the right and 5.9 degrees to the left and at atlas-axis it was 31.4 degrees to the right and 33 degrees to the left. After one-sided lesion of the alar ligament, there was an overall increase of 10.8 degrees or 30% of original rotation to the opposite side, divided about equally between the occiput-atlas and the atlas-axis. It is concluded that a lesion (irreversible overstretching or rupture of alar ligaments) can result in rotatory hypermobility or instability of the upper cervical spine.

Axis, Cervical Vertebra↗
PubMed1987

A monoclonal antibody that specifically inhibits human salivary alpha-amylase.

Our monoclonal antibody 88E8 specifically binds to and inhibits human salivary alpha-amylase (EC 3.2.1.1) and cross reacts negligibly with the pancreatic isoenzyme, inhibiting it by less than 1%, as compared with about 90% for the salivary isoenzyme. The antibody binds the S1 and S2 types of salivary alpha-amylase, but no pancreatic alpha-amylase isoenzyme forms. A pancreatic alpha-amylase assay involving 88E8 is under development, with alpha-glucosidase as auxiliary enzyme and p-nitrophenyl-maltoheptaoside as substrate; we give preliminary data on this assay. The assay has to be done by substrate start, because the antibody interacts very slowly with the enzyme in the presence of substrate. Assay results for pancreatic alpha-amylase correlate well with those for isoamylase assayed with use of an inhibitor from wheat-germ.

Antibodies, Monoclonal↗
PubMed1986

Pulmonary cytology in patients with the acquired immunodeficiency syndrome (AIDS).

Over a 2-yr period, 1982-1984, 181 pulmonary cytology specimens were obtained from 45 patients clinically suspected of having AIDS in an attempt to identify the various organisms and the cytologic atypias present in pulmonary cells. Cytologic correlations with autopsy findings were available for 28 of these cases (62%). Specimens were collected from sputum, bronchial washes and brushes, bronchoalveolar lavages, and pleural fluid. Of the 181 specimens, 121 (67%) were of diagnostic value. Depending on the cytologic technique, Pneumocystis carinii, cytomegalovirus, herpesvirus, and Candida were detected with varying frequency. The bronchial epithelial and glandular cell atypias, ranging from mild inflammatory reactive changes to marked cellular atypia, were noted most often in specimens from patients with pulmonary infections who were concurrently receiving oxygen therapy and/or chemotherapy for Kaposi's sarcoma or central nervous system lymphoma. An awareness of the wide range of AIDS-associated pulmonary cell atypias is required to rule out a diagnosis of malignancy.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Mechanism of enhancing effect of irradiation on production of IL-2.

In order to explain the mechanism of enhancing effect of irradiation on IL-2 production, assumption that radio-induced free radicals could act as a signal for mitogenesis and/or increase lipid peroxidation of T lymphocyte membrane phospholipids was made. Thus, production of metabolites of the lipoxygenase pathway in the arachidonic acid (AA) cascade, known to increase T cell proliferation and lymphokine production could be enhanced by irradiation. We have shown that (1) hydroxyl radical scavenger (DMSO) abolished IL-2 production, (2) inhibitor of the lipoxygenase pathway (NDGA) strongly decreased IL-2 production, (3) thin layer chromatography demonstrated a polar metabolite(s) of AA in increasing amounts according to the following order: non-irradiated resting cells, non-irradiated stimulated cells, irradiated resting cells, and irradiated stimulated cells. Investigations are in progress to identify this metabolite.

Arachidonic Acid↗
PubMed1985

Restoring capacity of immunomodifiers for radiation-induced inhibition of colony-forming T cells.

Six immunomodifier drugs have been studied with regard to their capacity for decreasing radiation-induced effects on lymphocytes. The T cell colony method was selected for this evaluation because this technique takes into account reproductive integrity of the lymphocyte. Irradiation was delivered either in vitro to murine splenocytes or in vivo (total body) at 0.75 Gy, a dose close to the D37 calculated for lymphocyte survival, using the same technique. Among immunomodifiers, only the drugs known for their specific action on ionizing radiation effects (quenching of free radicals) were shown capable of radiorestoration: this is essentially true for retinoic acid--even more than for its derivative--which restored the T cell colony formation up to 80% of the control at 10(-6) M final concentration in vitro. However, when given in vivo to irradiated mice, retinoic acid is active only at high doses.

Adjuvants, Immunologic↗
PubMed1985

The interaction of catalytic metal ions and ionizing groups in equilibrium studies and in transient intermediates of metal-substituted alcohol dehydrogenases.

The step of ternary complex interconversion in the reaction catalyzed by horse liver alcohol dehydrogenase has been resolved into five distinct molecular species with the aid of metal-substitution studies in combination with rapid-scanning spectrophotometry. A correlation with electronic absorption spectra at equilibrium provides structural insights into these intermediates. In contrast to NADH, NAD+ only leads to a conformational change of the protein when a negative charge has been created in the vicinity of the catalytic metal ion. This paper presents also a reevaluation of previous assignments of catalytically important groups in the light of some recent results.

Alcohol Oxidoreductases↗
PubMed1985

Specific immunoassay of alpha-amylase isoenzymes in human serum.

A monoclonal antibody (66C7) was prepared that specifically binds human salivary amylase (EC 3.2.1.1); it cross reacts with human pancreatic amylase by less than 1%. Two procedures are described for determination of isoamylases in human serum with this antibody: an enzyme immunoassay for determining amylase of salivary origin, and a routine method in which this amylase is immunoprecipitated and the remaining (pancreatic) amylase activity is assayed. Results by the two methods correlate well.

Antibodies, Monoclonal↗
PubMed1984

Mitomycin C-treated or irradiated concanavalin A-activated T cells augment the activation of cytotoxic T cells in vivo.

The activation of cytotoxic T lymphocytes (CTL) in vivo after immunization of normal or cyclophosphamide-treated mice with allogeneic cells was strongly augmented by the administration of mitomycin C-treated or irradiated concanavalin A-activated spleen cells (Con A-spl). This effect of the Con A-spl was abrogated by treatment with Anti-Thy 1 antibody plus complement, and was therefore presumably mediated by activated "helper" T cells. (The term "helper" cell is only operationally defined in this context and indicates that the augmenting irradiation resistant T cells are obviously not CTL precursor cells). These observations indicated (i) that even the cytotoxic response against allogeneic stimulator cells suffers in vivo from insufficient "helper" T cell activity, and (ii) that the injection of Con A-spl may serve as a simple procedure to apply this "helper" activity in vivo. This procedure was at least as effective as the repeated injection of interleukin 2 (IL-2)-containing cell supernatants with up to four 30-unit doses of IL-2 per mouse. IL-2-containing cell supernatants were found to mediate similar effects only if injected into the footpads but not intravenously. This was in line with the reported observation that IL-2 has an extremely short half-life in vivo. The injection of Con A-spl was also found to augment the proliferative response in the regional lymph nodes.

Animals↗
PubMed1984

Reaction of the Z isomer of 4-trans-(N,N-dimethylamino)cinnamaldoxime with the liver alcohol dehydrogenase-oxidized nicotinamide adenine dinucleotide complex.

The Z isomer of 4-trans-(N,N-dimethylamino)-cinnamaldoxime, (Z)-DMOX (lambda maxH2O 354 nm), forms a ternary complex with NAD+ and equine liver alcohol dehydrogenase. The 3-acetyl (3-acetyl-PdAD+), 3-thiocarboxamide (3-thio-NAD+), 3-iodo (io3PdAD+) and nicotinamide mononucleotide (NMN+) analogues of NAD+ also form ternary complexes with enzyme and (Z)-DMOX. These complexes are characterized by large red-shifts in the UV-visible spectrum of bound (Z)-DMOX (lambda max 428 nm for the NAD+ complex) and new spectral bands in the 280-340-nm region associated with the pyridine moieties of NAD+ and the NAD+ analogues. The ternary enzyme-NAD+-(Z)-DMOX complex is weakly fluorescent (lambda ex 430 nm; lambda em max 505 nm) and strongly quenches the residual tryptophan fluorescence of the enzyme-NAD+ binary complex. (Z)-DMOX binds with high affinity to the enzyme-NAD+ complex (Kd less than or equal to 4 X 10(-9) M at pH 8.75 and 25 degrees C), and similarly high affinities were found for the 3-acetyl-PdAD+, 3-thio-NAD+, and io3PdAD+ complexes. Binding is much weaker to the enzyme-NMN+ complex. The active site specifically substituted Co(II), Ni(II), Cu(II), and Cd(II) enzyme derivatives and the enzyme species lacking any metal ion at the active site (apoenzyme) also form ternary complexes with (Z)-DMOX in which the DMOX UV-visible spectrum is red-shifted (ranging from 43 to 83.5 nm). The complexes formed with the Zn(II) and Co(II) enzymes are characterized by relatively high affinities for (Z)-DMOX and by spectra that are independent of pH over the range 6-10. The affinity of the apoenzyme-NAD+ complex for (Z)-DMOX is much lower, and the spectrum of the complex is pH dependent with lambda max = 430 nm at pH 7 and lambda max = 397 nm at pH 10. The rate of (Z)-DMOX dissociation from the apoenzyme complex was found to be approximately 10(3)-fold greater than the rates observed for the metal ion substituted enzymes. The 280-340-nm spectral bands appear to result from the dihydropyridine moieties of covalent adducts formed between (Z)-DMOX and NAD+ and the NAD+ analogues. The large red-shifts of the (Z)-DMOX spectrum result from the bonding of the oxime nitrogen to a strong electrophilic center (either the active site zinc ion or the nicotinamide ring of NAD+.)(ABSTRACT TRUNCATED AT 400 WORDS)

Alcohol Dehydrogenase↗