Hydroxylation of 4,4'-methylenebis(2-chloroaniline) by canine, guinea pig, and rat liver microsomes

An in vitro microsomal mixed function oxidase enzyme system was used to study the phase I metabolism of 4,4'-methylenebis(2-chloroaniline) (MBOCA) by dog, guinea pig, and rat liver. TLC with color development and autoradiography, and HPLC with detection by UV absorbance and radioactivity flow monitoring were utilized to isolate metabolites. Reference standards of the N-oxidized metabolites were prepared by oxidation of MBOCA with 3-chloroperoxybenzoic acid and structures confirmed by mass spectrometry and proton NMR. These were utilized to identify the N-hydroxy and nitroso metabolites of MBOCA isolated from the microsomal incubations by comparison of their HPLC retention times and mass spectra. The structure of the o-hydroxy metabolite (ring, ortho to the amine) isolated from the microsomal incubations was elucidated by mass spectrometry and proton NMR. N- and o-hydroxylations of MBOCA were shown to increase with incubation time, microsomal protein, substrate, and NADPH concentration, and were inhibited by 2,3-dichloro-6-phenylphenoxyethylamine, an inhibitor of the microsomal mixed function oxidase enzyme system. Guinea pig liver microsomes oxidized MBOCA to the N-hydroxy metabolite predominantly, whereas the dog liver formed predominantly the o-hydroxylated metabolite, with significant amounts of the hydroxylamine as well. The rat liver formed lesser amounts of the N- and o-hydroxylated metabolites, but larger numbers of other polar compounds.

Calcium Buffer Injections Arrest Fucoid Egg Development by Suppressing Calcium Gradients

The polarity of fucoid eggs is fixed when rhizoidal growth starts. A steady flow of calcium ions into the incipient tip is thought to establish a high calcium zone, which is needed for tip formation and outgrowth. To test this model, we injected six different BAPTA-type calcium buffers into Pelvetia eggs at about 3 to 7 h before outgrowth normally starts. Critical final cell concentration of each buffer proves to block outgrowth (as well as cell division) for up to two weeks. The critical inhibitory concentration falls as the calcium dissociation constant, K_D, rises (and the buffers weaken) in the series of five buffers from 5,5' dimethyl-bapta (K_D 0.4 µM) to 4,4' difluoro-bapta (K_D = 5 µM); then finally rises again with the weakest buffer tested, 5,5' methylnitro-bapta (K_D = 60 µM). Thus calcium buffers with a K_D of about 5 µM prove most effective in blocking development. The effects of injecting a buffer do not depend upon the amount of coinjected calcium. To analyze these results, we imagine that each buffer acts to facilitate free calcium diffusion and thus suppresses gradient formation. This model leads to an exact equation and prediction of the concentrations of various buffers needed to inhibit development. The data fit this equation rather well if it is assumed that the free calcium concentration in the incipient tip is normally kept at about 10 µM and thus far above the general cytosolic level.

Pediatric burns--2 year survey of cases admitted to the Chang Gung Memorial Hospital

A total of 722 patients were admitted to the Burn Unit of Chang Gung Memorial Hospital over a 2-year period, of these 285 (39.5%) were under 15 years of age. The major cause of pediatric burns was scalding, 236 (82.8%). Most of the patients under age of 15 years had total burn surface under 20% (199 patients, 70%), and were discharged from the hospital within one month (263 patients, 91%). Treatments included debridement done in 98 patients (41.5%) and skin grafting in 81 patients (28%). Oxacillin-Resistant Staphylococcus Aureus infections were the most common complication (5.3%). The mortality rate was 5.3%.

The effects of protein kinase-C agonists on parathyroid hormone release and intracellular free Ca2+ in bovine parathyroid cells

High extracellular Ca2+ stimulates the accumulation of inositol trisphosphate and diacylglycerol in parathyroid cells and suppresses PTH release. Since diacylglycerol is an endogenous activator of protein kinase-C, these observations would suggest that activation of protein kinase-C is associated with inhibition of PTH release. However, phorbol esters, which stimulate protein kinase-C activity, have been reported to enhance PTH release. To clarify the role of protein kinase-C in the regulation of PTH secretion, we studied the responses of parathyroid cells to phorbol myristate acetate (PMA), bryostatin-1, and 1,2-dioctanoylglycerol (diC8). PMA and bryostatin-1 translocated protein kinase-C activity from the soluble to particulate fractions of cell homogenates. Phosphotransferase activity in the particulate fractions increased from 21 +/- 4% to 93 +/- 6% of the total activity after 10 min of exposure to PMA (10(-6) M) and from 21 +/- 2% to 69 +/- 2% after 5 min of exposure to bryostatin-1 (10(-7) M). These three structurally different agonists of protein kinase-C also altered the typical secretory response to Ca2+ in parathyroid cells. At 2.0 mM extracellular Ca2+, PMA (10(-6) M) bryostatin-1 (10(-7) M), and 1,2-dioctanoylglycerol (3 x 10(-4) M) blunted the suppressive effects of high Ca2+ on secretion, thus stimulating PTH release 252 +/- 45%, 122 +/- 20%, and 485 +/- 95% over control levels, respectively. However, at low extracellular Ca2+, these agents inhibited maximal PTH release. Since changes in the intracellular free Ca2+ concentration ([Ca2+]i) may be important in the control of PTH release, we investigated whether protein kinase-C agonists changed the relationship between extracellular Ca2+ and PTH release by affecting [Ca2+]i. In PMA-treated cells, the intracellular Ca2+ response to raising extracellular Ca2+ from 0.5 to 1.5 and 2.0 mM was reduced to 50 +/- 1% and 63 +/- 3% of that in control cells, respectively (P less than 0.005; n = 7-11). Specifically, PMA preincubation reduced the initial intracellular Ca2+ transient with raising extracellular Ca2+ from 0.5 to 2.0 mM and with adding 4.0 mM Sr2+. The sustained phase response to high Ca2+, but not to Sr2+, was also attenuated after incubation with PMA. We conclude that protein kinase-C agonists suppress PTH release at low extracellular Ca2+ and enhance PTH release at high extracellular Ca2+. The effects on secretion at high extracellular Ca2+ may be related to the ability of protein kinase-C agonists to change the sensitivity of [Ca2+]i to high extracellular Ca2+ in these cells.

Strain difference in galactokinase level and susceptibility to the teratogenic effect of dietary galactose in mice: I. Teratogenic and embryopathic effect

Congenital cataracts have been noted to occur in infants when either the mother or the mother and infant have reduced activity of the enzymes galactokinase (GK) or galactose-1-phosphate uridyl transferase (GALT). Studies were undertaken to elucidate the possible genetic and dietary fetomaternal interactions leading to the presumptive galactose teratogenesis noted in two inbred strains of mice differing in GK activity. Pregnant A/J (high erythrocyte GK activity 134.18 +/- 17.89 mU/gm Hb) and C57BL/6J (low erythrocyte GK activity 55.05 +/- 11.39 mU/gm Hb) mice were treated with a diet containing either 25% or 50% galactose throughout gestation. A significantly higher percentage of C57BL offspring (92.3%) were observed to have lens opacities when their mothers were fed a high-galactose diet, whereas no increase in lens pathology was observed in the offspring of similarly treated A/J mothers. Additionally, reciprocal matings were carried out so that all offspring were genetically equivalent in terms of GK activity. However, when the mother had low GK activity, a significant incidence of lens opacities was present in their offspring; this was not found when the mother had high GK activity. After weaning, no difference in the incidence of lens opacities was observed when the 25% galactose diet was introduced to the offspring of these reciprocal crosses, providing additional support for a maternal dietary influence on the development of lens opacities.

Calcium requirement in nitrogen fixation in the cyanobacterium Synechococcus RF-1

Under diurnal 16/8-h light-dark cycles, ethyleneglycol-bis-(β-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) at 1 mM completely blocked the appearance of rhythmic N2-fixing activity in Synechococcus RF-1. Ca(2+) at 2 mM, when supplied either together with or several hours after the EGTA application, restored the nitrogenase activity, whereas, when Ca(2+) was supplied several hours later, the peak of nitrogenase activity was shifted from the dark to the light period in which the activity is normally suppressed. Sr(2+) also reversed the inhibition by EGTA, but only partially. When O2 in the gas phase above the culture was below 1%, the inhibition of nitrogenase activity by EGTA was reduced to less than 20% of the control value without EGTA. Thus Ca(2+) appears to be required by the cell to protect its nitrogenase from inactivation by O2. In media without EGTA, a close correlation between nitrogenase activity and concentrations of Ca(2+) was also observed.

Streptococcal protein G-gold complex: comparison with staphylococcal protein A-gold complex for spot blotting and immunolabeling

Protein G, a cell wall protein isolated from human group G streptococci strain G148, binds in a similar manner as protein A from Staphylococcus aureus to the Fc portion of IgG molecules. Indeed, protein G has been proposed as a superior Fc binding protein due to its broader species reactivity. Thus, we have prepared a complex of protein G with particles of colloidal gold and determined its applicability for spot-blot analysis and postembedding immunolabeling by comparing it with protein A-gold complex. By spot-blot analysis no difference in binding of protein G-gold or protein A-gold to IgG molecules from a whole spectrum of animal species was observed. Moreover, using rabbit, sheep, or goat anti-rat albumin antibodies to detect nitrocellulose-immobilized rat albumin or antigenic sites in paraffin and Lowicryl K4M thin sections from rat liver, no difference was found with protein G-gold or protein A-gold. Similarly, no difference in binding to protein G-gold or protein A-gold was observed with a battery of monoclonal antibodies. However, in contrast to expectations, protein A-gold reacted well with both sheep and goat IgG molecules; indeed, for the light and electron microscopic localization of albumin with sheep or goat antibodies it was as efficient as protein G-gold. These results demonstrate, therefore, that both protein G-gold and protein A-gold are useful second step reagents for immunolabeling and that protein G-gold was not a superior probe in the systems tested.

Inhibition of metabolic cooperation in Chinese hamster V79 cells by various organic solvents and simple compounds

Gap-junctional intercellular communication is a biological process implicated in the regulation of cell proliferation and differentiation. Metabolic cooperation between 6-thioguanine-sensitive and resistant Chinese hamster cells, in vitro, has been used as a means to detect chemicals which can inhibit this form of intercellular communication. To further characterize this in vitro system as a potential screening assay for potential teratogens, tumor promoters and reproductive toxicants, a series of common solvents as well as other chemicals representing eight different functional groups, i.e., alcohols with straight or side chains, glycols, ketones, esters, ethers, phenols, aldehydes, amines and amino compounds and oxygen-heterocyclic compounds, were tested for their ability to inhibit colony-formation and to inhibit metabolic cooperation. A wide range of effects were observed which suggested a structure/activity relationship between a chemical's ability to inhibit gap junction-mediated intercellular communication and the cytotoxicity of a chemical. Possible mechanisms affecting the modulation of gap junctional communication by these chemicals are discussed.

Freezing Characteristics of Cultured Catharanthus roseus (L). G. Don Cells Treated with Dimethylsulfoxide and Sorbitol in Relation to Cryopreservation

The freezing behavior of dimethylsulfoxide (DMSO) and sorbitol solutions and periwinkle (Catharanthus roseus) cells treated with DMSO and sorbitol alone and in combination was examined by nuclear magnetic resonance and differential thermal analysis. Incorporation of DMSO or sorbitol into the liquid growth medium had a significant effect in the temperature range for initiation to completion of ice crystallization. Compared to the control, less water crystallized at temperatures below -30 degrees C in DMSO-treated cells. Similar results were obtained with sorbitol-treated cells, except sorbitol had less effect on the amount of water crystallized at temperatures below -25 degrees C. There was a close association between the per cent unfrozen water at -40 degrees C and per cent cell survival after freezing for 1 hour in liquid nitrogen. It appears that, in periwinkle suspension cultures, the amount of liquid water at -40 degrees C is critical for a successful cryopreservation. The combination of DMSO and sorbitol was the most effective in preventing water from freezing. The results obtained may explain the cryoprotective properties of DMSO and sorbitol and why DMSO and sorbitol in combination are more effective as cryoprotectants than when used alone.

Cryopreservation of Alkaloid-Producing Cell Cultures of Periwinkle (Catharanthus roseus)

A procedure for cryogenic storage of alkaloid producing cell lines of periwinkle, Catharanthus roseus (L.) G. Don., has been developed. The procedure differs from established cryopreservation protocols in several aspects. Specifically, 4-day-old suspension subcultures of three cell lines were precultured in nutrient media supplemented with 1 molar sorbitol for 6 to 20 hours. The cells were then incubated in nutrient media with 1 molar sorbitol plus 5% DMSO in an ice bath for 1 hour and, thereafter, were frozen in this solution at a cooling rate of 0.5 degrees C per minute to -40 degrees C prior to immersion in liquid nitrogen (LN). After rapid thawing in a 40 degrees C water bath, the regrowth of LN stored cells was achieved by transferring them without washing onto filter paper discs over nutrient media solidified with agar for a period of 4 to 5 hours. The filter paper discs with the cells were then transferred to fresh media of the same composition for regrowth. The viability immediately after thawing as evaluated by the 2,3,5-triphenyl tetrazolium chloride method was about 60% of controls. Suspension cultures established from LN stored cells retained the capability for alkaloid synthesis and accumulation.

Freezing injury and root development in winter cereals

Upon exposure to 2 degrees C, the leaves and crowns of rye (Secale cereale L. cv ;Puma') and wheat (Triticum aestivum L. cv ;Norstar' and ;Cappelle') increased in cold hardiness, whereas little change in root cold hardiness was observed. Both root and shoot growth were severely reduced in cold-hardened Norstar wheat plants frozen to -11 degrees C or lower and transplanted to soil. In contrast, shoot growth of plants grown in a nutrient agar medium and subjected to the same hardening and freezing conditions was not affected by freezing temperatures of -20 degrees C while root growth was reduced at -15 degrees C. Thus, it was apparent that lack of root development limited the ability of plants to survive freezing under natural conditions.Generally, the temperatures at which 50% of the plants were killed as determined by the conductivity method were lower than those obtained by regrowth. A simple explanation for this difference is that the majority of cells in the crown are still alive while a small portion of the cells which are critical for regrowth are injured or killed.Suspension cultures of Norstar wheat grown in B-5 liquid medium supplemented with 3 milligrams per liter of 2,4-dichlorophenoxyacetic acid could be cold hardened to the same levels as soil growth plants. These cultures produce roots when transferred to the same growth medium supplemented with a low rate of 2,4-dichlorophenoxyacetic acid (<1 milligram per liter). When frozen to -15 degrees C regrowth of cultures was 50% of the control, whereas the percentage of calli with root development was reduced 50% in cultures frozen to -11 degrees C. These results suggest that freezing affects root morphogenesis rather than just killing the cells responsible for root regeneration.

Abscisic Acid-induced freezing resistance in cultured plant cells

The effect of abscisic acid (ABA) on the cold hardiness of cell suspension was investigated. Cell suspension cultures of winter wheat (Triticum aestivum L. cv Norstar), winter rye (Secale cereale L. cv Cougar), and bromegrass Bromo inermis Leyss treated with 7.5 x 10(-5) molar ABA for 4 days at 20 degrees C could tolerate -30 degrees C, whereas the control cultures tolerated only -7 to -8 degrees C. The optimum concentration for increasing the cold hardiness of the cultures was 7.5 x 10(-5) molar. The degree of cold hardiness and the rate of hardening obtained by ABA treatment was significantly higher than that induced by low temperature alone. Of ten species tested, ABA was only effective on those cultures which were capable of cold hardening upon exposure to low temperatures. The results suggest that ABA bypasses the cold requirement for hardening and also suggests that ABA triggers the genetic system(s) responsible for inducing the hardening process.

Deep Undercooling in Woody Taxa Growing North of the -40 degrees C Isotherm

The freezing of deep undercooled water in cold-hardened 3-year-old stems of 16 woody taxa was studied in mid-January by differential thermal analysis. The initiation temperature and the size of the low temperature exotherm (LTE) were compared for nonthawed, thawed, and freeze-killed stems. In general, the initiation temperature of the LTE for nonthawed stems occurred at a lower temperature than for thawed stems and freeze-killed stems. In some cases, no LTE was detected in nonthawed stems although a LTE was detected after thawing. The size of the LTE increased after thawing the stem and also after the stem was freeze killed. The LTE observed in one species disappeared upon exposure to continuous low sub-zero temperatures. Results suggest that undercooling which subsequently results in the LTE in woody stems is due to the cell wall and the plasma membrane. During periods of prolonged freezing, cellular water migrates from the cells which undercool to extracellular ice. This results in a concentration of cell solutes which lowers the homogeneous nucleation temperature of the cell sap. The cold hardiness of nonthawed and thawed stems was compared by a controlled freeze test. In general, thawing had little effect on the survival temperature whereas it had a marked effect on the initiation of the LTE.

Subcutaneous fat necrosis of the newborn. A case report

A 3-day-old infant, born to a mother with preeclampsia, suffered intrauterine asphyxia and subsequently had multiple erythematous subcutaneous plaques and nodules. The clinical setting, the skin manifestations, and the histologic appearance of the lesions were diagnostic of subcutaneous fat necrosis of the newborn. Transient thrombocytopenia was noted with the appearance of the skin lesions, but returned to normal as the skin lesions spontaneously resolved.

Plague in camels and goats: their role in human epidemics

In 1976, in a small, remote Libyan village, one apparently sick camel was slaughtered and skinned, and the camel meat was distributed for human comsumption. A few days later, 15 villagers suffered a severe febrile illness. Of the five individuals who had participated in the killing and dispensation of the camel, all were dead within four days. When samples of serum from nine of the remaining patients were examined, seven were found to be positive for plague as determined by the passive hemagglutination test. Another six persons became ill after killing two goats, and the serum of one goat contained antibodies to Yersinia pestis. Because all of the remaining patients except one were treated early enough, they recovered. These incidents confirm previous reports that the camel and the goat are susceptible to naturally occurring plague infection and have a significant role in the dissemination of human plague.

Effect of bacille Calmette-Guérin on the immune response of BALB/c mice to a tumor allograft

The effect of dosage and route of inoculation of bacille Calmette-Guérin (BCG) on immune response to allogeneic tumor cells was investigated. BALB/c mice were tested 14 and 21 days after injection of EL-4 lymphoma for spleen-cell cytotoxicity against EL-4 cells in vitro and for complement-dependent, antibody-mediated lysis of tumor cells. BCG treatment had no measurable effect on the antibody-mediated lysis of tumor cells, but spleen-cell cytotoxicity was significantly increased in mice treated with 10(4) or 10(8) BCG by the intraperitoneal route; no such increase occurred when BCG was given by the oral or subcutaneous routes. The cytotoxic effector cells were primarily thymus-derived, since treatment of spleens with rabbit antiserum to mouse brain serum decreased cytotoxicity titers by approximately 90%. Within the framework of these experiments, the intraperitoneal route of BCG inoculation resulted in a more effective immune stimulation than the oral or subcutaneous routes.

Forced calcium entry and polarized growth of Funaria spores

We have used both steady electric fields, and gradients of the divalent ionophore, A23187, to control the point at which rhizoids emerge from spores of the common moss Funaria hygrometrica. The spores were grown in a medium containing calcium nitrate as the only major salt. Spores tend to form rhizoids towards the positive electrode, with a half maximal response to a difference of 4-8 mV across each cell. They also tend to form rhizoids towards the end of higher ionophore concentration in response to A23187 gradients. Both of these responses are the same at pH 5.5 and 8.0. Our tentative explanation is that Funaria spores tend to form rhizoids where most calcium enters. However, the point of chloronema emergence is scarcely affected by steady fields of up to 45 mV/cell. Moreover, when steady fields are applied across already developed rhizoids or chloronemata, their subsequent growth is directed towards the negative electrode in both cases, with rhizoids giving a 50% response at only 3-5 mV/cell, and chloronemata being less responsive.

Effects of membrane potential on calcium fluxes of Pelvetia eggs

(45)Ca(2+) fluxes across the plasma membrane of zygotes of the fucoid alga, Pelvetia fastagiata (J. Ag.) De Toni, were studied in artificial sea waters of various potassium concentrations. Except for two cases, hyperpolarization of the cell membrane (with low [K(+)]) increases, and depolarization (with high [K(+)]) decreases the influx of Ca(2+) over the range of [K(+)] studied (1-100 mM). The fractional increases of influx during hyperpolarization are close to the fractional increases in membrane potential but the decreases during depolarization are much smaller than those in membrane potential. In two anomalous cases, the influxes of (45)Ca(2+) at a potassium concentration of 30 mM were about 20% higher than the control value instead of being 10% lower.The effluxes of (45)Ca(2+) are increased by both hyperpolarization and by depolarization. On balance (and excepting the two anomalous cases) the net result of hyperpolarization should be to increase and that of depolarization to decrease intracellular [Ca(2+)].