Neurotransmitter modulation of VIP release from cat cerebral cortex

The cortical release of vasoactive intestinal polypeptide-like immunoreactivity (VIP-LI) in vivo was examined by superfusion of the pial surface of the cerebral cortex of the cat. The modulation of cortical VIP release by several neurotransmitters [gamma-aminobutyric acid (GABA), opioids, norepinephrine, acetylcholine, and glutamate] normally present in the cerebral cortex was studied by administering respective agonists and antagonists for their receptors. Although GABA and opiate agonists did not influence the resting release of VIP-LI, GABA antagonists (picrotoxin and bicuculline) and opiate antagonists (naloxone and naltrexone) significantly elevated the resting release. The evoked release from cortex of VIP-LI (by electrical stimulation of the cortex or mesencephalic reticular formation) was suppressed by GABA and mu- but not delta-, kappa-, or sigma-opioid receptor agonists. Glutamate and kainic acid increased the resting release of VIP-LI from the cerebral cortex. Noradrenergic (alpha 2 but not alpha 1) displayed an inhibitory effect on the evoked release of cortical VIP-LI release. Resting VIP-LI release was enhanced by cholinergic agents (carbachol). The facilitatory effects of mesencephalic reticular formation stimulation on VIP-LI release were demonstrated by atropine. These observations suggest characteristic interactions reflecting the circuitry modulating the activity of cortical VIP-releasing neurons.

Isolation of antibodies for phosphotyrosine by immunization with a v-abl oncogene-encoded protein

Immunization of rabbits with a tyrosine-phosphorylated v-abl protein resulted in the production of antibodies for the v-abl protein and for phosphotyrosine. The antiphosphotyrosine antibodies could be purified by affinity chromatography with O-phosphotyramine coupled to Sepharose. These antibodies detected a variety of tyrosine-phosphorylated proteins, including receptors for peptide growth factors. The usefulness of these antibodies was demonstrated by the detection of previously unidentified tyrosine-phosphorylated proteins in v-src-, v-abl-, and v-erbB-transformed cell lines.

Immunoprophylaxis of infection with hepatitis B virus in infants born to hepatitis B surface antigen-positive carrier mothers

Infants born to carrier mothers positive for hepatitis B surface antigen (HBsAg) and hepatitis B e antigen (HBeAg) received 5 micrograms of hepatitis B virus (HBV) vaccine on four occasions. Group 1 received vaccine only, group 2 received vaccine plus hepatitis B immune globulin (HBIG) at birth, and group 3 received vaccine plus HBIG at birth and at one month. Infants born to HBeAg-positive mothers (group 4) received a reduced dose of vaccine (2.5 micrograms) on three occasions as well as HBIG at birth. As compared with 78.4% of the control group (infants whose parents refused vaccination) who became chronic HBV carriers at the age of 14 months, the protective efficacy rate of vaccination was 75.3% in group 1,85.5% in group 2,89.7% in group 3, and 87.2% in group 4. HBV vaccine (5 micrograms) was also given to infants born to HBsAg-positive, HBeAg-negative mothers on four on four occasions. The antibody response to HBsAg in vaccine recipients was 12% after the first dose, 44% after the second dose, and 75% and 100% at six months and 1.5 years of age, respectively.

Combined passive and active immunization for interruption of perinatal transmission of hepatitis B virus in Taiwan

We attempted a clinical trial to interrupt transmission of hepatitis B virus (HBV) infection from hepatitis B surface antigen (HBsAg) positive and hepatitis Be antigen (HBsAg) positive mothers to their infants in Taiwan. Screening of 5,595 pregnant women revealed that 856 (15.3%) were HBsAg positive. Three hundred and sixty-one (42.2%) of the HBsAg positive pregnant women were HBeAg positive. Infants born to HBsAg and HBeAg positive mothers were randomized into 3 groups to receive the HBV vaccine alone or combined with hepatitis B immune globulin (HBIG). HGV vaccine was given at 2, 6, and 10 weeks after birth. Group I received HBV vaccine alone while Group II received HBV vaccine in combination with HBIG at birth and group III received HBV vaccine plus HBIG at birth and again at one month old. Group IV constituted the control group when their parents refused vaccination. At 6 months of age, the HBV carrier rate was 23.7% (9/38) in Group I, 11.1% (4/36) in Group II, and 5.3% (2/38) in Group III infants. Compared with 90% of infants who became HBV carriers in the control group (Group IV), the efficacy of HBV vaccination in preventing HBV infection among these high risk infants at the 6th month was 73.7% in Group I, 87.7% in Group II, and 94.1% in Group III. The antibody to HBsAg (anti-HBs) positivity rate in sera of Group I, II, III infants at 6 months of age was 79.0%, 88.9% and 94.7%, respectively. These initial results indicate that combined passive and active immunization is efficacious in interrupting perinatal transmission of HBV infection.

Studies on the in vivo release of vasoactive intestinal polypeptide (VIP) from the cerebral cortex: effects of cortical, brainstem and somatic stimuli

The release of vasoactive intestinal polypeptide (VIP) from the surface of the sensorimotor (parietal) cortex of anesthetized cats was measured by radioimmunoassay (RIA) procedures. Two types of anesthetics were examined (chloralose-urethane and halothane). Increasing the dose or concentration of anesthetics produced a suppression of electrocortical activity and resulted in a reduction in the resting release of VIP from cerebral cortex. The mean rate of resting release of endogenous VIP in cats anesthetized with chloralose-urethane was 16.8 +/- 4.6 fmol/30 min/cm2 cortex. Although there were differences in the basal levels of VIP-like immunoreactivity (VIP-LI) among different animals, the baseline levels of VIP-LI varied little during the initial period of 6-7 h period of anesthesia with chloralose-urethane (40 and 300 mg/kg). Examination of representative electrocorticography which corresponded with the superfusion period revealed an association between stable levels and a relatively invariant pattern of electrical activity. All experimental manipulations were carried out during the period of stable release. The rate of release was increased by focal, unilateral stimulation of the cerebral cortex both ipsilateral and contralateral to the side of stimulation (3.2 +/- 1.1 and 1.4 +/- 0.5 times the resting release, respectively). Bilateral stimulation of the mesencephalic reticular formation (MRF) produced a frequency-dependent increase in cortical VIP release over the range of 60-100 Hz. Bilateral electrical stimulation of sciatic nerves at intensities that recruit A delta and C fibers failed to consistently increase the release of VIP-LI from the cortex in chloralose-urethane anesthetized cats but did evoke a significant increase of cortical VIP output in cats anesthetized with 1.5 and 1% halothane. Removal of calcium ions from the superfusing fluid and substitution of cobalt (a calcium channel blocker) or EDTA (a calcium chelating agent) for calcium ions did not affect the resting release of endogenous VIP, but attenuated the increase in VIP release normally evoked by electrical stimulation of the cortical surface or MRF. Tetrodotoxin (TTX), which blocks sodium channels and thus blocks the propagation of nerve impulses, did not influence the resting release of VIP. TTX, at concentrations that prevent the increase in VIP release evoked by veratridine, greatly enhanced the surface-stimulated release but abolished the increase in VIP release evoked by MRF stimulation.(ABSTRACT TRUNCATED AT 400 WORDS)

Localization of tyrosine kinase-coding region in v-abl oncogene by the expression of v-abl-encoded proteins in bacteria

A series of plasmids containing different segments of the v-abl oncogene have been constructed to express different portions of the v-abl protein in bacteria. The tyrosine kinase activity of these proteins was determined by an in vitro assay employing histones or angiotensin II as substrates for the v-abl-encoded tyrosine kinase. These experiments show that the 5'-1.2 kilobases of v-abl is necessary and sufficient to produce an active tyrosine kinase which is functional as a monomeric soluble protein. The kinase-coding region corresponds to the minimal region of v-abl required for the transformation of fibroblasts. The kinase-coding region also coincides with the conserved protein sequences which are found in other tyrosine kinases. A compact domain of the v-abl protein including this kinase-coding region can accumulate to high levels in bacteria. The C-terminal region of the v-abl protein is not needed for the kinase activity and is rapidly degraded in bacteria.

Studies on RNA ligase activity in the brain and liver cells of mouse

RNA ligase in eukaryotic mammalian cells was studied by using mouse brain and liver cell extracts as enzyme sources and Oligo A as substrates. RNA ligase activity was determined by measuring the formation of alkaline phosphate-resistant product from 5'-32P-terminated Oligoribonucleotides. Under appropriate conditions, the activity of this enzyme in brain and liver cells may vary between 16-49 mU/ml. The joining way between donor and acceptor is 5'-P----3'-OH. Further studies were carried out by using synthetic UpCpU and 32pNp as substrates and crude enzyme preparations from extracts of cell nuclei of brain and liver as enzyme sources. RNA ligase activity was examined by homochromatography and autoradiography. A clear joining product was demonstrated and then isolated from the reaction mixture by DEAE-Sephadex A25 column chromatography. The eluted fractions were identified by DEAE-cellulose thin layer chromatography. The joining product was hydrolyzed either with KOH or with alkaline phosphatase, the autoradiographic spot of the product disappeared. In this case the joining way between donor and acceptor is 3'-P----5'-OH instead of 5'P----3'-OH. All this indicated that in extracts of mouse brain and liver cells most probably exists some other kind of RNA ligase, which differs from the T4 RNA ligase in the joining way.

A v-sis oncogene protein produced in bacteria competes for platelet-derived growth factor binding to its receptor

The oncogene of simian sarcoma virus, v-sis, encodes a protein which is homologous to human platelet-derived growth factor (PDGF). This v-sis-encoded protein was expressed in bacteria using an inducible promotor of lambda phage. Soluble extracts from these bacteria contained a substance which competed with 125I-PDGF for PDGF receptor sites in fibroblast membranes. The receptor competition activity was correlated with the presence of the v-sis-encoded protein as assessed by genetic and immunochemical criteria. These results directly demonstrate that the v-sis oncogene product is functionally related to PDGF.

CNS stimulation and PGE2 release. I. Depolarizing agents

Radioimmunoassayable PGE2 was reliably detected in the ventriculocisternal perfusates of chloralose-urethanized cats (557-1481 pg/min; +/- 1 S.E.). Examination of the levels of PGE2 in sequential 30 min samples for periods of up to 6 h revealed that the basal secretion rates of this prostaglandin did not fluctuate ina statistically significant fashion during this extended interval. The addition of either K+ (50 mM) or veratridine (7.5 X 10(-5) M) were shown to reliably evoke a long lasting increase (190-210%) in radioimmunoassayable PGE2 in the ventriculocisternal superfusates. In the majority of experiments, the elevated PGE2 showed a return to prestimulation levels within 60 min after the removal of the depolarizing agent. The ability of two depolarizing agents which act by different mechanisms to produce PGE2 release, and the likelihood that the stimulus-dependent increases were not due to altered clearance, metabolism or dilution makes it likely that the PGE2 levels in the extravascular-extracellular fluid were elevated secondary to increases in neuronal activity.

[Cephalosporin C production by solid state fermentation with rice grains]

The purpose of the present study was to investigate the production of cephalosporin C in solid state fermentation with rice as a basal substrate. Among the various grains as basal substrates tested, rice was the best one and the worst one was soyflour . Among the varieties of rice examined, Tsailai rice was the best. The proposed best formula for the fermentation medium on the basis of 10 g rice grain consists the following % of the ingredients, 0.65, peptone, 0.65, ammonium sulfate, 0.26, inositol, 1.3 (v/w), trace element solution, 0.65 calcium carbonate, 0.65 calcium sulfate, 0.065, potasium sulfate, 1.3, sucrose, 0.13, DL-methionine and 2.6, methyl oleate. Of the strains of C. acremonium used, strain M8650 -R-3 was superior to strain ATCC 14553. The optimum inoculum density was 2.8 X 10(8) spores of C. acremonium M8650 -R-3 per g substrate. The initial moisture content of the medium at 49-51%, the water activity at 0.985, and the fermentation temperature at 25 degrees C were found as the optimun . After 7 days of fermentation, the maximum yield of cephalosporin C was 6420 micrograms per g substrate and the total cephalosporin C equivalent potency was 11,000 micrograms per g substrate.

The mouse c-abl locus: molecular cloning and characterization

The mouse c-abl gene, part of the sequence of which was captured in Moloney murine leukemia virus to generate the transforming gene (v-abl) of the Abelson murine leukemia virus, has been isolated and characterized. The c-abl locus spans 40 kb in the mouse genome with the v-abl homologies distributed in no less than ten clusters along 25 kb of the cloned DNA. Partial sequence of the v-abl homologous regions indicates that v-abl derived from c-abl mainly by splicing of multiple exons of the c-abl gene. The c-abl sequences can be subdivided into two regions: a tyrosine kinase coding sequence distributed among eight small clusters on the 5' end of the gene and a C-terminal portion consisting of one small and one large cluster, which are needed neither for the tyrosine kinase activity nor for the transforming ability of v-abl. Apparent exon/intron boundaries in the homologous kinase-coding regions of c-abl and c-src are at different locations.

In vivo studies on the basal and evoked release of cholecystokinin and vasoactive intestinal polypeptide from cat cerebral cortex and periventricular structures

In cat, radioimmunoassay revealed high concentrations of vasoactive intestinal polypeptide (VIP) and cholecystokinin (CCK) (approximately 10-90 ng/g wet weight tissue) in various regions of the cerebral cortex and in periventricular structures. Superfusion of cat cerebral cortex or perfusion from the lateral ventricle to the cisterna magna with artificial cerebrospinal fluid (CSF) was carried out in cats anesthetized with chloralose-urethane. The superfusate was assayed for VIP- and CCK-like immunoreactivity (VIP-LI and CCK-LI) simultaneously. Basal efflux of VIP-LI was 13.8 +/- 4.1 fmol/30 min/cm2 cortex and 31.6 +/- 5.0 fmol/30 min in ventriculo-cisternal superfusate. Basal efflux of CCK-LI, assayed in the same superfusate sample, was 10.7 +/- 2.5 fmol/30/min/cm2 cortex in cortical cup superfusate and 25.6 +/- 4.4 fmol/30 min in ventriculo-cisternal superfusate. The addition of potassium (50 mM) and veratridine (7.5 X 10(-5) M) to the superfusate produced significant increases in the levels of VIP-LI in both ventricular and cortical effluents. The potassium evoked release of VIP-LI and CCK-LI was inhibited by the substitution of cobalt (4 mM) for the calcium ion in the perfusion media; basal efflux was not affected. Separation of immunoreactivity by gel filtration chromatography demonstrated the CCK-LI in cat cortical tissue co-chromatographed with the COOH-terminal 4, 8, 33 and 39 amino acid peptide fragments of CCK and with a larger molecule. In contrast, the immunoreactivity in cortical and ventricular superfusate obtained during basal and evoked release co-migrated with authentic CCK octapeptide. For VIP, all immunoreactivity in tissue extract of cerebral cortex existed as a single peak which co-migrated with authentic VIP-28. The molecular pattern in cortical superfusate corresponded to that found in tissue extract.

Studies on the release by somatic stimulation from rat and cat spinal cord of active materials which displace dihydromorphine in an opiate-binding assay

Using the spinal superfusion procedure, in anesthetized rats and cats, the presence of active factors which displace dihydromorphine in brain opiate binding studies, has been observed. Separation of this activity on a Sephadex G-10 column reveals the presence of two fractions which occur before (Fraction I) and after (Fraction II) the salt peak which account for over 70% of the observed dihydromorphine-displacing activity. The ratio of activity in Fraction II/Fraction I is 33 and 21, in the resting spinal perfusates of the rat and cat, respectively. High intensity, bilateral stimulation of the sciatic nerve in cats, results in a 30- and 5.4-fold increase in the levels of Fraction I and Fraction II, respectively, over pre-stimulation levels. In rat, bilateral stimulation of the hind paws, resulted in a frequency-dependent increase in the levels of Fraction I (1.9- and 3.2-fold at 5 and 50 Hz, respectively). Dynorphin 1-13 fragment elutes at least partly in Fraction I. With regard to Fraction II, the peak co-chromatographs with hexapeptide derivatives of enkephalin. Met- and Leu-enkephalin (Fraction III), elute off the column at a point where opiate receptor displacing activity is relatively small. Electrophoretic separation of Fraction I radioreceptor activity of alkaline and acid pH on agarose columns revealed two principle peaks which co-migrated with alpha-neoendorphin and dynorphin 1-13. Fraction II activity appeared primarily in a single peak which was isographic with enkephalin hexapeptides. Using radioimmunoassays, detectable levels of dynorphin and Met-enkephalin were observed and sciatic nerve stimulation resulted in significant increases. Neither column-coupled radioreceptor assays nor radioimmunoassays revealed the presence of beta-endorphin. The present experiments demonstrate the releasability by high intensity somatic stimulation of a variety of opioid peptides present in spinal terminals. Significantly, however, the majority of this activity appears to be found in fractions different from those of the pentapeptide enkephalins.

Cellular RNA homologous to the Abelson murine leukemia virus transforming gene: expression and relationship to the viral sequence

To examine the expression of the cellular homolog of the Abelson murine leukemia virus transforming gene (the v-abl sequence), a DNA probe representing the v-abl sequence was prepared. The probe detected two cytoplasmic polyadenylic acid-containing c-abl RNAs of about 6.5 and 5.5 kilobases in a variety of rodent cells, and slightly larger RNAs were detected in human cells. These two RNA species were found in all normal tissues or cell lines examined, but at differing concentrations: liver cells had the least, fibroblastic cell lines had the most. By using a probe able to detect the cellular but not the viral gene, the two RNAs were shown to be present in Abelson murine leukemia virus-transformed cells at levels found either in their untransformed counterparts or in similar cell types transformed by other means. The target cells of the virus have a somewhat elevated level of the two RNAs although expression of the c-abl gene is not restricted to these cells. The v-abl sequence lacks 0.35 and 0.85 kilobases of the c-abl RNA on the 5' and 3' ends, respectively. Thus, the Abelson murine leukemia virus transforming gene is an internal fragment of the transcript of a normal cellular gene.

Selective antagonism of the antinociceptive effect of intrathecally applied alpha adrenergic agonists by intrathecal prazosin and intrathecal yohimbine

We have attempted to define the alpha adrenoceptor subtype(s) on which intrathecally applied alpha adrenergic agonists act to produce their antinociceptive effect. The potencies of intrathecal (i.t.) prazosin or i.t. yohimbine to antagonize the elevations of thermal nociceptive threshold induced by i.t. 2-[2,6-diethylphenylamino]-2-imidazoline (ST-91), methoxamine or norepinephrine (NE) were determined in the rat. Tail-flick and hot plate tests were used to determine thermal nociceptive threshold. At the ID50 level, the alpha-2 selective antagonist yohimbine was significantly more potent than the alpha-1 selective antagonist prazosin at blocking the analgesia produced by the alpha-2 selective agonist ST-91, whereas prazosin was significantly more potent than yohimbine at antagonizing the analgesia produced by the alpha-1 selective agonist methoxamine or by the nonselective alpha agonist NE. Analgesic doses of methoxamine evoked a readily observable disturbance of motor and autonomic function, whereas such effects were not observed after analgesic doses of ST-91 or NE. Both i.t. methoxamine and i.t. ST-91 elevated thermal nociceptive threshold in rats depleted of lumbar spinal cord NE by pretreatment 7 days before with i.t. 6-hydroxydopamine. Our results suggest that stimulation of either one of two separate populations of postsynaptic spinal alpha adrenoceptors will inhibit spinal nociceptive transmission. One of these populations appears to be composed of alpha-2 adrenoceptors. The subtype classification of the alpha adrenoceptors composing the other population remains unclear.

Cloning and analysis of reverse transcript P160 genomes of Abelson murine leukemia virus

Circular duplex reverse transcripts of the genome of a strain of Abelson murine leukemia virus that encodes a 160,000-molecular-weight protein were isolated, cleaved with HindIII restriction endonuclease, and cloned into the unique HindIII site of lambda phage Charon 21A. Recombinant phage clones, some of which were infectious in transfection assays, were found to contain a 789-base-pair region specific for Abelson murine leukemia virus; this region is not found in other strains of this virus. The extra sequence was localized by restriction endonuclease and electron microscopic heteroduplex analysis. Sequence analysis showed no homology at the ends of the extra sequence, implying that it was deleted by an event that did not utilize sequence homology. The sequence of this unique region has an open reading frame through its entirety.

Characterization of the Abelson murine leukemia virus-encoded tyrosine-specific protein kinase

There is sufficient evidence that the A-MuL V protein is a tyrosine-specific protein kinase. There are methods for detecting this kinase activity and this kinase has been expressed in E. coli. Because the information coding for the tyrosine-specific protein kinase is present in normal mouse cells, such an enzyme must have a normal physiologic function. The elucidation of this physiologic function and the understanding of the role of this enzyme activity in neoplastic transformation is the challenge of the future.

Expression of an Abelson murine leukemia virus-encoded protein in Escherichia coli causes extensive phosphorylation of tyrosine residues

A segment of the Abelson murine leukemia virus (A-MuLV) genome was inserted into an Escherichia coli plasmid designed to allow the expression of the protein encoded by the viral gene. Bacteria expressing the A-MuLV-encoded protein were isolated; they had new phosphorylated proteins in which the phosphate was linked to tyrosine residues. These proteins included many that must be E. coli protein. One phosphotyrosine-containing protein of 62,000 molecular weight had reactivity with antiserum specific for authentic A-MuLV protein. The A-MuLV protein thus appears to be a tyrosine-specific protein kinase which is active in E. coli.

Effect of beta-carotene supplementation on reproductive performance of dairy heifers

Three trials were conducted to determine the effect of feeding supplemental beta-carotene on reproductive performance of Holstein heifers. In each trial, the animals were randomly assigned to either a control or treatment group. Animals in the treatment groups received 300 mg supplemental beta-carotene daily for the test periods which varied from 6 to 8 weeks in length. To facilitate sample collections and observations, estrus was synchronized with two injections of 25 mg PGF(2alpha) at 11 day intervals. The first injection was after 2 weeks of feeding supplemental beta-carotene. Blood serum beta-carotene concentrations were higher in the heifers fed supplemental beta-carotene as compared to concentrations in control heifers after 1 week of feeding and this difference increased throughout the test periods. The interval from the second injection of PGF(2alpha) to onset of estrus was shorter in the control heifers as compared to that interval in heifers supplemented with beta-carotene (trial 1,44.0 vs 56.0 hr; trial 2, 51.3 vs 70.8 hr; trial 3, 40.7 vs 62.5 hr, respectively). The intervals from PGF(2alpha) administration to the preovulatory LH peak (43.3 vs 61.5 hr) and ovulation (69.3 vs 85.9 hr) were also shorter in the control heifers in trial 3. No significant differences were found among treatments in the number of heifers that expressed estrus, the blood serum progesterone concentrations or the conception rates in any of the three trials.

Heterodyne laser radar SNR from a diffuse target containing multiple glints

A coherent laser radar performance model is formulated using the Huygens-Fresnel principle for a near-field or far-field diffuse target which may contain a number of glints. The received signal is calculated for a truncated Gaussian-transmitted beam mixed with a matched Gaussian or a uniform local oscillator (LO) beam. In general, the uniform LO beam provides a good or better mixing than the matched Gaussian beam. The effects of beam truncation and receiver aperture size on the received signal level are presented. In the case of a far-field diffuse target, an increase in SNR is obtained if the receiver aperture increases to about three times the transmitter aperture, or if the transmitter aperture increases to about three times the receiver aperture. The target signature statistics and the weather statistics are considered as random parameters in the evaluation of receiver performance characteristics.

Transfection of fibroblasts by cloned Abelson murine leukemia virus DNA and recovery of transmissible virus by recombination with helper virus

A cloned, permuted DNA copy of the Abelson murine leukemia virus (A-MuLV) genome was capable of eliciting the morphological transformation of NIH/3T3 fibroblasts when applied to cells in a calcium phosphate precipitate. The efficiency of the process was extremely low, yielding approximately one transformant per microgram of DNA under conditions which give 10(4) transfectants per microgram of other DNAs (e.g., Moloney sarcoma virus proviral DNA). The DNA was able to induce foci, even though the 3' end of the genome was not present. The transforming gene was thus localized to the 5' portion of the genome. The transformed cells all produced viral RNA and the virus-specific P90 protein. Transmissible virus could be rescued from these cells at very low frequencies by superinfection with helper virus; the rescued A-MuLV virus had variable 3' ends apparently derived by recombination with the helper. Dimerization of the permuted A-MuLV cloned genome to reconstruct a complete provirus did not improve transformation efficiency. Virus could be rescued from these transformants, however, at a high efficiency. Cotransfection of the permuted A-MuLV DNA with proviral M-MuLV DNA yielded a significant increase in the efficiency of transformation and cotransfection of dimeric A-MuLV and proviral M-MuLV resulted in a high-efficiency transformation yielding several thousand more transformants per microgram than A-MuLV DNA alone. We propose that helper virus efficiently rescues A-MuLV from transiently transfected cells which would not otherwise have grown into foci. We hypothesize that multiple copies of A-MuLV DNA introduced into cells by transfection are toxic to cells. In support of this hypothesis, we have shown that A-MuLV DNA sequences can inhibit the stable transformation of cells by other selectable DNAs.

Molecular cloning and amplification of the adenylate cyclase gene

A segment of DNA containing cya, the gene for adenylate cyclase [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1], has been isolated from Salmonella typhimurium. The phage lambda gt4 was used as a cloning vector and adenylate cyclase-positive hybrid phages were isolated that complemented adenylate cyclase-negative bacteria. The cloned DNA fragment encodes a polypeptide of molecular weight 81,000 that gives rise to adenylate cyclase activity. This protein represents a functional mutant of the bacterial adenylate cyclase. When the cya gene was amplified by inserting into a multicopy plasmid, the enzyme activity was overproduced 20-fold, but the cyclic AMP level increased only 60%, suggesting several probable regulatory mechanisms. Overproduction of enzymes by recombinant DNA techniques can be a useful probe of relationships in the metabolizing organism in vivo.

The identification of distinct protein kinases and phosphatases in the prokaryote Salmonella typhimurium

The finding of protein phosphorylation in prokaryotes (Wang, J. Y. J., and Koshland, D. E. (1978) J. Biol. Chem. 253, 7605-7608) has been pursued further. The prokaryotic organism Salmonella typhimurium is shown to contain at least 10 phosphorylated proteins with serine or threonine phosphates which are produced by the action of at lest four protein kinases. The protein kinases are distinguished by their substrate specificity, their chromatographic behavior, and their inhibition patterns. The phosphorylations are reversible, and more than one protein phosphatase activity exists in these cells. The presence of specific protein kinases and phosphatases suggests that this form of protein covalent modification is involved in the regulation of different cellular functions in prokaryotes as it is in eukaryotes.

Studies on the phenomenon of latent propagated sensation along the channels. I. The discovery of a latent PSC and a preliminary study of its skin electrical conductance

By combining electrical impulse stimuli with mechanical ones, we are able to trace out a new line of feeling, coincident with the classical channel course. Impulse stimulation was carried out at the Jing point of the Large Intestine or Stomach channel, namely Shangyan or Lidui. With a small rubber nipple, light taps were applied on the skin along the lines perpendicular to the channel and crossing over the acupuncture points; a specific propagational numb feeling at the points of the channel could be found. By linking up these points of specific feeling, an imaginary line which is exactly the classical Large Intestine or Stomach channel can be traced out. This line is called the "latent propagational sensation line along the channels" because, unless through tapping, no prominent sensation of propagation could be felt. Employing an impulsive electrical generator and an all-wave commutating circuit linked to a micro-ammeter, the skin conductance was measured over the latent PSC of the Large Intestine channel lying between the wrist and 5 cm above the elbow joint. Results were compared to those locations of 1 cm apart from the channel course, i.e. the control sites devoid of acupuncture points or channels. At most acupuncture points or any site of the channel course on all of the 10 subjects under examination, there was greater electrical conductance maxima than there was at control sites. This fact indicates that not only the acupuncture points, but the entire course of latent PSC are also of higher electrical conductance.

Wave-front interpretation with Zernike polynomials

Several low-order Zernike modes are photographed for visualization. These polynomials are extended to include both circular and annular pupils through a Gram-Schmidt orthogonalization procedure. Contrary to the traditional understanding, the classical least-squares method of determining the Zernike coefficients from a sampled wave front with measurement noise has been found numerically stable. Furthermore, numerical analysis indicates that the so-called Gram-Schmidt method and the least-squares method give practically identical results. An alternate method using the orthogonal property of the polynomials to determinem their coefficients is also discussed.

Evidence for protein kinase activities in the prokaryote Salmonella typhimurium

Evidence for phosphorylation of proteins by protein kinases has been found in Salmonella typhimurium despite previous indications that protein kinase action is absent in prokaryotes. At least four proteins have been found to be phosphorylated. Serine and threonine phosphates have been isolated from acid hydrolysates of these proteins after in vivo and in vitro labeling. The kinases do not phosphorylate histones, casein, or phosvitin. It would appear that phosphorylation as a regulatory control exists in prokaryotes.

Phase-compensated optical beam propagation through atmospheric turbulence

The modulation transfer function and the irradiance profile of a phase-compensated laser beam propagating through atmospheric turbulence are calculated for various values of the normalized transmitter diameter, D/r(0). Both focused Gaussian beam and collimated beam with modal phase corrections of arbitrary orders are considered using Zernike polynomials as basic correcting modes. Examples are given for low-order corrections such as tilt, focus, and astigmatism as well as for higher order corrections. The beam quality criteria, defined in terms of Strehl ratio, spot radius, and energy in a bucket, are used to measure the beam performance with different compensating modes. The effects on the beam propagation of central obscuration of the transmitter are also examined, and numerical results are given.

Passive optical diagnostics of combustion flows

A passive ir detection method based on the monochromatic radiative transfer equation is proposed to probe both a homogeneous and a nonhomogeneous medium for the simultaneous determination of temperature and species concentrations. The problem of determining these thermodynamic variables and their sensitivities is solved by a ratio technique for a homogeneous medium. The solution requires inversion of a linear matrix equation when there are more than one absorbing species at the observing frequencies. A generalized Abel inversion method utilizing multifrequency multiangle scannings is developed to solve for the nonhomogeneous 2-D distribution of these parameters. Two special cases which assume combinations of axisymmetric and asymmetric distributions of the unknown parameters are also treated.

Laser absorption methods for simultaneous determination of temperature and species concentrations through a cross section of a radiating flow

An active laser absorption technique is proposed for simultaneous determination of temperature and species concentrations of a combustion flow. For homogeneous medium, the conventional method of ratio of the Boltzmann's population distribution factors to determine temperature is extended to include influence of the interfering species from measurements of multiple monochromatic absorptions. It is further shown that this technique may be used to retrieve two-dimensional thermodynamic variables across a selected cross section. The problem of solving a nonhomogeneous case is reduced to that of a homogeneous one if an appropriate multidirection scanning technique is employed.

Numerical solutions in remote sensing

Several aspects of the behavior of Fredholm integral equations are examined in this paper. It is shown that collocation methods are better in general than least squares methods in linear approaches. The amplification of random noise inherent to the numerical inversion of the equation puts an upper limit to the information content of an ill-conditioned system. An estimation based on the magnitude of SNR is proposed for a system that lacks statistical information to determine the information content and to reconstruct the solution profile. To reduce the numerical instability of matrix inversion, some specific kernel transformations are discussed. Illustrative examples are given and compared to results of other approaches. An alternative linear approach that orthonormalizes the kernels-is also proposed. The linear approach was then employed in solving the radiative transfer equation with temperature-independent kernels. The necessary variable separation in linear inversions was examined. Iteration refinement was found necessary to accommodate the strong nonlinearity of high temperature sensing.