The application of enzyme immunoassay to the study of salivary IGA

In the study of salivary IgA, solid-phase enzyme immunoassay has been able to show that 1) the assay is reliable, 2) minimal loss of IgA occurs from centrifuging or by elimination of insoluble mucins, 3) IgA can be easily measured in fractions from sucrose gradient sedimentation, 4) freezing alone is sufficient to preserve salivary IgA, 5) the concentration in normal saliva in 11 persons ranged from 15 to 240 mg/L (-/x = 81), and 6) an abnormal saliva contained less than 6 ug/L, the detection limit for this EIA.

Purification and partial characterization of hyaluronidase from five pace snake (Agkistrodon acutus) venom

A hyaluronidase (EC 3.2.1. 35) was isolated and purified from Agkistrodon acutus venom. The purification procedure included CM-Sephadex C-50 chromatography, gel-filtration on Sephadex G-75 and CM-Sephadex C-25 chromatography. The purified preparation of the enzyme was homogeneous on polyacrylamide gel electrophoresis at pH 4.3, a 45-fold purification being obtained. The hyaluronidase was a glycoprotein (positive PAS staining) with a molecular weight of 33,000 and a pI of 10.3. No hemorrhagic activity was found. The hyaluronidase had an optimum pH of 3.5-5.0 and an optimum temperature of 37 degrees C. It was heat sensitive, was more stable in the acidic than in the neutral region, and lost its activity in the alkaline region. Fe2+, Cu2+ and heparin inhibited the venom hyaluronidase. The Km value for hyaluronic acid was 6.2 X 10(-3) mg/ml.

The action of six antagonists of the excitatory amino acids on neurones of the rat spinal cord

The differential susceptibility to blockade by six antagonists of the excitatory actions produced by a number of acidic amino acids has been determined. Four of these, DL-alpha-aminoadipate, 2-amino-5-phosphonovalerate, 2-amino-6-phosphonocaproate and gamma-D-glutamylglycine block the action of N-methyl-D-aspartate (NMDA) most effectively and those of L-glutamate, trans-1-amino-1,3-dicarboxycyclopentane (trans-ADCP) and kainate the least. Cis-2,3-piperidine dicarboxylate resembles the other four, save in that kainate excitations are also powerfully blocked. L-glutamate diethylester was most effective against L-glutamate and least against NMDA: kainate and trans-ADCP excitations were also relatively unaffected. The data support the hypothesis of the existence of at least three classes of amino acid receptor (NMDA-, L-glutamate- and kainate-excited), and the possibility of a fourth category activated by trans-ADCP must be considered.

Cerebral edema and ophthalmoplegia reversed by mannitol in a new case of insulin-dependent diabetes mellitus

Cerebral edema is a sometimes fatal complication of diabetic ketoacidosis which occurs unpredictably and when biochemical parameters show improvement. A case of a young, newly diagnosed insulin-dependent diabetic boy who developed this complication while receiving a low-dose continuous insulin infusion is reported. Two hours after treatment signs of headache, ophthalmoplegia, and blurred disc margins suggested early cerebral edema. Despite fluid restriction, avoidance of alkali, and phosphate supplementation, cerebral edema ensued three hours later. This complication was then reversed by administration of mannitol. Our patient's ophthalmoplegia, unlike typical diabetic ophthalmoplegia, improved immediately and completely resolved within two weeks after this episode. It is concluded that the use of mannitol in the cerebral edema of diabetic ketoacidosis is beneficial if it is instituted promptly.

Interaction of myosin subfragment 1 with Cibacron Blue F3GA

Cibacron Blue F3GA and its immobilized derivatives have been shown before to bind and inhibit nucleotide-dependent enzymes and, among them, myosin subfragment 1. Experiments have been carried out to examine the mechanism of the subfragment 1--dye interaction. Binding of subfragment 1 to immobilized dye (Affi-Gel Blue) does not involve the ATP binding site on myosin. Subfragment 1 hydrolyzes MgATP and CaATP while bound to the Affi-Gel Blue column. Inactivated subfragment 1, which contains [3H]ADP noncovalently trapped at the active site, binds and elutes from the Affi-Gel Blue column in the same manner as unmodified, active protein. Free Cibacron Blue inhibits the ATPase activity of subfragment 1. The inhibition is pH, salt, and time dependent. Complete inhibition correlates with the noncovalent binding of four to five dye molecules per mole of subfragment 1. Three to four of these dye molecules can be preferentially removed from subfragment 1 in the presence of 1 M KCl without relieving the inhibition. This inhibition, which can be traced to one dye molecule per subfragment 1, is reversible and is facilitated in the presence of MgADP and MgATP, suggesting that the dye does not bind at the active site of subfragment 1. Our observations are explained in terms of hydrophobic and electrostatic protein--dye interactions.

Solid-phase selection of human T lymphocyte subpopulations using monoclonal antibodies

This report describes a novel solid-phase technique for the positive selection of human T lymphocyte subsets labeled by indirect immunofluorescence with monoclonal anti-bodies. Fluorescein labeled normal human T cells or a T cell line were fractionated on plastic culture dishes precoated with affinity chromatography purified anti-fluorescein antibodies. Cell binding was specific for fluorescein, and was both time and temperature dependent. Bound cells were eluted at 37 degrees C with fluorescein-L-lysine. The eluted cells were enriched with highly viable and functional human T cell subsets. Thus Leu3 monoclonal antibody selected cells were shown to provide helper activity in the pokeweed mitogen induced IgM and IgG immunoglobulin secretory response of autologous B cells. The Leu2 antibody selected T cells suppressed both IgM and IgG secretory responses. In addition, studies with the monoclonal antibody 1G11, which binds to an antigen expressed on acute lymphocytic leukemia (T-ALL) cells and the T-ALL derived cell line RPMI-8402, demonstrated that this solid-phase technique can be used to select for cells which are present at low frequencies in a mixed population. It thus provides a simple and reproducible means for the preparative isolation of lymphocyte subsets associated with autoimmune and neoplastic disease for functional and biochemical analysis.

Comparative pharmacokinetics of 1-(2-chloroethyl)-3-(2,6-dioxo-1-piperidyl)-1-nitrosourea in rats and patients and extrapolation to clinical trials

The plasma pharmacokinetics of 1-(2-chloroethyl)-3-(2,6-dioxo-1-piperidyl)1-nitrosourea (PCNU) were determined in ambulatory rats and in patients receiving PCNU chemotherapy in Phase 1 and II studies. After derivativization to the methyl carbamate, both rat and human PCNU plasma levels were measured by gas chromatography-mass spectrometry. Comparison of the tolerated dose levels and pharmacokinetics of PCNU to the values determined for 1,3-bis(2-chloroethyl)-1-nitrosourea in humans indicated that PCNU has a lower plasma drug area under the curve at equitoxic doses. We conclude that PCNU may show less clinical efficacy than 1,3-bis(2-chloroethyl)-1-nitrosourea in the treatment of solid tumors.

Lymphocytotoxic anti-LewisbH antibody

We wish to report strong lymphocyte crossmatch incompatibility attributable to anti-Lea antibody. The prospective renal transplant recipient was Le(a-b-) and her serum contained potent anti-Lea and anti-LebH antibodies. Despite the fact that were able to demonstrate greater B lymphocyte than T lymphocyte Lewis(a+) antigenicity, this serum was capable of causing greater than 80% cytotoxicity of Le(a+) and Le(b+)O or A2 whole lymphocyte populations. Antibody activity was completely inhibited by Lewis substance. This inhibition was specific and did not interfere with HLA antibody activity.

The postexcitatory effects of acidic amino acids on spinal neurones

The excitation of some neurones in the spinal cord of rats by L-glutamate and L-aspartate is followed by a period of reduced excitability. This effect is not observed after excitation by D-glutamate nor, in the case of Renshaw cells, by acetylcholine. The depressions following L-glutamate were reduced by bicuculline and those after aspartate by strychnine, suggesting that they may have been caused through decarboxylation of the excitatory amino acids to yield the inhibitory compounds gamma-aminobutyric acid and beta-alanine, respectively.

The interaction of Cibacron Blue F3GA with troponin and its subunits

Binding of troponin to Cibacron Blue F3GA-agarose column and its selective release from the gel in the presence of 0.5 M KCl provides the basis for a new purification method. The two-step procedure consists of isoelectric precipitation of tropomyosin and chromatography of the resultant crude troponin supernatant on Affi-Gel Blue column. Adsorption of troponin to the immobilized dye appears to occur through the troponin-T subunit. Troponin-I and troponin-C do not bind to the blue agarose column, whereas troponin-T binds to it very tightly. Binding of the dye to troponin-T prevents formation of troponin-T-troponin-C complex, but does not interfere with direct interaction of troponin-T with troponin-I. The activity of troponin in conferring calcium sensitivity on actomyosin ATPase is not affected by Cibacron Blue. Circular dichroism and difference absorption measurements of complexes of the blue dye with troponin and its subunits reveal the presence of a tight binding site on whole troponin and on troponin-T (KA greater than or equal to 10(6) M). The existence of weak binding sites for the dye on troponin and all of its subunits is deduced from difference absorption studies. Cibacron Blue appears to be a sensitive probe for subunit interactions in troponin.

Dissimilar effects of ultraviolet light on HLA-D and HLA-DR antigens

Since HLA-DR antigens are closely related to HLA-D antigens, we studied the effect of low-dose ultraviolet irradiation on the ability of human lymphocytes to induce a proliferative response in mixed lymphocyte culture (HLA-D) and on the serologic reactivity of B lymphocyte HLA-DR antigens. We found (1) no alteration in the serologic definition of DR antigens despite the abrogation of the induction of proliferative responses in mixed lymphocyte culture, (2) no evidence that ultraviolet light (UVL) stimulated suppressor cells contributed to the loss of allostimulation, and (3) no evidence that the abrogation of the induction of proliferative responses could be modified by increasing the number of UVL exposed lymphocytes in mixed lymphocyte culture. These findings suggest that HLA-D and HLA-DR antigens are different molecularly, but are also consistent with the concept that certain active metabolic processes are required of stimulator cells for allostimulation and that these processes are UVL sensitive.

The frequency of suicides around major public holidays: some surprising findings

This paper analyzes the recorded number of U.S. daily suicides, 1972-1976. The paper shows that: there is a dip in suicides on and just before major public holidays; there is a peak in suicides just after these holidays; and, the dip in suicides is somewhat larger than the peak--hence, there is a net decrease in suicides around the holidays. On balance, the holidays appear to reduce the number of suicides, not increase them, as previously believed. In addition, previous research has focussed on the negative psychological impact of holidays. Our findings indicate that holidays have a positive component, which should be taken into account in future research.

Radiation exposure to medical personnel during iodine-125 seed implantation of the prostate

Radiation exposure to operating room personnel was measured by thermoluminescent dosimeters and an ionization chamber during a simulated iodine-125 seed implantation of the prostate gland. The exposure rates at points around the implanted phantom were measured and compared with the calculated values. The data suggested that even with a schedule of 25 prostate implants per year, exposure levels would not exceed 5% of the recommended maximum limits for occupationally exposed personnel.

Accommodation dynamics I. Range nonlinearity

We show the presence of a new nonlinearity in accommodation dynamics. Positive accommodation is slower when the eye is operating in the near range; conversely, relaxation of accommodation is apparently slower during work in the far range. Latency of accommodation is unaffected by working range. This new dynamic range nonlinearity has been defined in connection with a continuing research study of accommodation responses in normal subjects and in clinic patients. Instrumentation and analysis procedures are described.

Effect of hyperoxia, hypoxia, and maturation on superoxide dismutase activity in isolated alveolar macrophages

The influence of ambient O2 tensions and of cell maturation on superoxide dismutase activity were studied in tissue culture--maintained mouse alveolar macrophages. Cultivation under hyperoxic conditions (PO2 about 640 mmHg) for 24 hours was associated with a significant increase in superoxide dismutase activity as compared with normoxic conditions (PO2 approximately 150 mmHg). (Hyperoxia: superoxide dismutase = 7.9 +/- 4.0 (SD); normoxia: superoxide dismutase = 4.4 +/- 1.7 units X mg cell protein-1 P less than 0.05). Hypoxic exposure (PO2 approximately 15 mmHg) was associated with a significant decrease in superoxide dismutase compared to normoxic controls (hypoxia: 2.2 +/- 0.6; normoxic: 3.8 +/- 0.6 units X mg protein-1 P less than 0.01). This decrease was found only after 168 hours of in vitro hypoxia. The in vitro maturation of alveolar macrophages cultivated in air was associated with a progressive increase in superoxide dismutase activity per 10(6) cells, although superoxide dismutase activity per unit protein remained constant. Molecular O2 may modify cell superoxide dismutase activity by altering intrinsic enzyme regulation. The increase in superoxide dismutase activity with hyperoxia and the decrease with hypoxia are consistent with but not unequivocally establish an important role for superoxide dismutase in protecting against cellular O2 toxicity.

Superoxide dismutase (SOD) activity in hypoxic mammalian systems

Superoxide Dismutase (SOD) activity was compared in rabbit peritoneal macrophages (ambient PO2 approximately 15 Torr) and alveolar macrophages (ambient PO2 approximately 100 Torr) and in brain, lung, cardiac muscle, and skeletal muscle of chromically hypoxic mice(ambient PO2 approximately 50 Torr) and normoxic mice (ambient PO2 approximately 150 Torr). Peritoneal macrophages (PM) have significantly less SOD activity than alveolar macrophages (AM) (PM: 2.94 +/- 0.49 (mean +/- SD); AM:6.03 +/- 1.60 units-mg protein -1 (P less than 0.01)). SOD activity of lung and brain homogenates from the hypoxic mice was significantly less than from the normoxic controls. Heart and skeletal muscle SOD activities were not significantly different. These studies show that limitations of O2 supply are associated with reductions in SOD and are consistent with the thesis that SOD plays an important role in protection against oxygen toxicity in mammalian systems.

Some comparative aspects of the organ distribution of superoxide dismutase activity in the freshwater turtle, Pseudemys scripta elegans

1. Superoxide dismutase activities in five tissues of the relatively anaerobic freshwater turtle were compared with SOD activities in the same tissues of two mammalian species (mouse and rabbit) with a more usual pattern of dependence on O2 availability. 2. SOD activities in brain, lung and skeletal muscle, but not liver or cardiac muscle, are significantly lower in the turtle. The turtle also shows differences in the pattern of relative SOD activities in various tissues as compared to the two mammalian species. 3. The data indicate that a relationship does exist between SOD activities and O2 exposure in intact vertebrate systems, and is consistent with a physiological role for SOD in tissue O2 metabolism.