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J F Jackson

Publications and source records attributed to J F Jackson.

At least 37 records · Page 2Linked to original sources
PubMed1988

Isolation, characterization, and evolutionary aspects of a cDNA clone encoding multiple neuropeptides involved in the stereotyped egg-laying behavior of the freshwater snail Lymnaea stagnalis.

The cerebral neurosecretory caudodorsal cells (CDCs) of the freshwater pulmonate snail Lymnaea stagnalis control egg laying, an event that involves a pattern of stereotyped behaviors. The CDCs synthesize and release multiple peptides, among which is the ovulation hormone (CDCH). It is thought that each peptide controls a specific aspect of the processes involved in egg laying. We isolated and characterized a CDC-specific cDNA clone that encodes the ovulation hormone (CDCH). RNA blot analysis and in situ hybridization experiments demonstrated that the CDCs are the major cell groups in the cerebral ganglia that transcribe the CDCH gene. In addition to CDCH, the 259-amino acid-long CDCH preprohormone contains 11 other predicted peptides. The overall homology of the CDCH preprohormone with the egg-laying hormone (ELH) preprohormones of the marine opisthobranch snails Aplysia californica and A. parvula is very low (29 and 26%, respectively). However, a more detailed comparison revealed a highly differential pattern of conservation of peptide regions. Significant homology was found between the regions containing (1) CDCH and ELH, (2) repeated pentapeptides, (3) alpha-caudodorsal cell peptide and alpha-bag cell peptide, and (4) 2 regions representing as yet unidentified peptides. Insignificant homology was found when comparing regions containing the other predicted peptides. The conserved peptides probably control similar aspects of the egg-laying fixed action patterns in these distantly related gastropod species. The pentapeptide region exhibits the highest level of homology (75%); in addition, an extra pentapeptide has been generated on the CDCH precursor. This indicates a vital function of these peptides in Aplysia, as well as in Lymnaea species.

Amino Acid Sequence↗
PubMed1987

Differential expression of nicotinic acetylcholine receptor genes in innervated and denervated chicken muscle.

We have studied the mRNAs encoding all four subunits of the acetylcholine receptor in 13-day embryonic, innervated and denervated chicken pectoral muscle. In all three states the transcript sizes of the alpha, beta-, gamma- and delta-subunit mRNAs were approximately 3.2, 2.8, 1.8 and 1.9 kb respectively. Denervation was found to result in a large increase in the steady-state levels of each mRNA compared with those in innervated muscle. This increase was 8- to 9-fold for the beta and delta subunits and approximately 12-fold for the alpha subunit. The evidence obtained shows a coordinate regulation of the acetylcholine receptor genes in response to denervation. Interestingly, no gamma-subunit transcript was detected in innervated muscle, while significant levels were detected in embryonic and denervated tissue. This evidence suggests that there exists in a non-mammalian muscle acetylcholine receptor an additional subunit, analogous to the bovine epsilon subunit, and shows that the extra-junctional receptor of adult denervated muscle is produced by the same set of mRNAs which produce the major form of the receptor in embryonic muscle.

Animals↗
PubMed1987

Protein kinase C activity and hexamethylenebisacetamide-induced erythroleukemia cell differentiation.

Hexamethylenebisacetamide (HMBA) is a potent inducer of murine erythroleukemia (MEL) cell differentiation. The mechanism of action of HMBA is not known. In this study we provide evidence that protein kinase C has a role in inducer-mediated MEL cell differentiation: (i) HMBA induces the formation of a soluble, proteolytically activated form of protein kinase C that is catalytically active in the absence of Ca2+ and phospholipid; (ii) the protease inhibitor leupeptin blocks formation of this activated form of the kinase and inhibits HMBA-induced MEL cell hemoglobin accumulation; (iii) phorbol 12-myristate 13-acetate (PMA) inhibits HMBA-induced MEL differentiation and causes depletion of total protein kinase C activity; (iv) MEL cells depleted in protein kinase C activity by culture with PMA are resistant to induction by HMBA; (v) upon removal of PMA, restoration of MEL cell sensitivity to HMBA is correlated with reaccumulation of protein kinase C activity; and (vi) MEL cells grown to density arrest are both depleted of protein kinase C activity and resistant to HMBA. Together, these results suggest that HMBA-mediated MEL cell differentiation involves a protein kinase C-related mechanism and the proteolytically activated form of the kinase, which does not require Ca2+ or phospholipid for its catalytic activity.

Acetamides↗
PubMed1987

Autotransfusion: quality of blood prepared with a red cell processing device.

The quality of blood salvaged at operation and prepared with the Dideco Autotrans BT 795 autotransfusion device was compared with that of donor blood in 41 patients having cardiac surgery involving cardiopulmonary bypass. Saved blood had a higher haemoglobin concentration (17.3 v. 13.1 g dl-1; P less than 0.001), a higher 2,3-diphosphoglycerate concentration (5.3 v. 1.1 mmol litre-1; P less than 0.00001), higher white cell count (17.1 X 10(9) litre-1 v. 4.1; P less than 0.00001), higher pH (7.5 v. 6.6; P less than 0.00001) and a more physiological potassium concentration (5.4 v. 8.8 mmol litre-1; P less than 0.00001) than donor blood. Saved blood platelet count was 34.5 X 10(9) litre-1 compared with 146.24 X 10(9) litre-1 (P less than 0.00001) and its heparin concentration was 0.64 u. ml-1. We conclude that this autotransfusor is a useful aid to blood conservation, producing good quality red cells with relatively normal pH and potassium values. However, modification of the centrifugation and washing is required to lessen the high white cell count and heparin concentrations found in the saved blood.

Adolescent↗
PubMed1987

Purine Nucleoside Transport in Petunia Pollen Is an Active, Carrier-Mediated System Not Sensitive to Nitrobenzylthioinosine and Not Renewed during Pollen Tube Growth.

Adenosine and guanosine are transported into Petunia hybrida pollen by a saturable, carrier-mediated mechanism. The energy poisons carbonylcyanide-m-chlorophenylhydrazone, 2,4-dinitrophenol, 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole, and N,N'-dicyclohexylcarbodiimide all inhibit uptake, suggesting an energy coupled (active) transport process. Transport takes place against a concentration gradient, strongly favoring an active transport mechanism. The purine nucleoside transport in Petunia pollen differs from that already reported for pyrimidine nucleosides in that it exhibits a significantly higher K(m) for nucleoside and is not so severely inhibited by the polyamine, spermine. Like that for the pyrimidine nucleosides uridine and cytosine, however, the system exhibits a broad pH optimum, is inhibited by sulfydryl-binding reagents, while the potent inhibitors of nucleoside transport in animal cells, nitrobenzylthioinosine and dipyridamole, have no effect. Transport of both purine and pyrimidine nucleosides in germinating pollen decreases steadily with time, a finding consistent with reports that RNA synthesis and DNA repair are early events of pollen germination and tube elongation. However, since these precursors are often used to demonstrate nucleic acid synthesis, it cannot be ruled out that the lack of precursor transport itself leads to scoring nucleic acid synthesis as negative. The results indicate that the newly synthesized pollen tube membranes contain little or no nucleoside transporters.

Journal Article↗
PubMed1985

The molecular basis of the neuro-endocrine control of egg-laying behaviour in Lymnaea.

The biosynthesis, axonal transport and release of multiple peptides by the egg-laying controlling caudodorsal cells (CDC) of Lymnaea stagnalis were studied. High performance gel permeation chromatography was used to resolve newly synthesized peptides after pulse-chase experiments with radioactive amino acids. The precursor is a 35 kd polypeptide which is produced in the CDC somata. It gives rise to intermediate products (20 kd, 10 kd and 7 kd) and a number of end products which include a approximately 4.5 kd (the ovulation hormone, CDCH), a 1.5 kd peptide (the autotransmitter) and other peptides (6 kd, 3.5 kd and 2 kd). The end products are transported in neurosecretory granules to the CDC axon terminals in the cerebral commissure where they are released into the medium during electrical discharges of the CDC system. A cDNA clone encoding part of the CDCH precursor was isolated from a Lymnaea CNS cDNA library by differential hybridisation and use of synthetic oligonucleotide probes. Examination of the deduced amino acid sequence indicates that the precursor contains additional peptides, besides CDCH.

Animals↗
PubMed1985

Pyrimidine nucleoside uptake by petunia pollen: specificity and inhibitor studies on the carrier-mediated transport.

Transport of pyrimidine nucleosides into germinating Petunia hybrida pollen is carrier-mediated, and, except for thymidine, is inhibited by the energy poisons N,N'-dicyclohexylcarbodiimide, 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole, 2,4-dinitrophenol, and carbonylcyanide-m-chlorophenylhydrazone. Kinetic studies with analogs deoxyuridine and 5-bromodeoxyuridine show that they too are taken up faster than thymidine and inhibited by the energy poisons. These and other analogs inhibit uridine and cytidine transport more than thymidine, as do the inhibitors parachloromercuribenzoic acid, N-ethylmaleimide, phenylarsine oxide, o-phenanthroline, ethylene diamenetetraacetate, and ethylene glycol-bis (beta-aminoethyl ether) N,N,N'N'-tetraacetic acid. Citrate, phosphate, succinate, and tartrate inhibited uptake of all pyrimidine nucleosides. The specific inhibitor of nucleoside transport in animal cells, nitrobenzylthioinosine, has little effect on pollen transport. Uridine and deoxyuridine accumulate against a concentration gradient, suggesting active transport. Except for thymidine, however, transported nucleosides were found to be extensively phosphorylated. Until mutant plants are found which do not phosphorylate uridine, it is not possible to decide unequivocally between active and nonactive transport for uridine. However, consistent with a low level of DNA synthesis in germinating Petunia pollen, it is clear that thymidine transport is nonactive and relatively slow. It is apparent from these experiments that a more sensitive way to study DNA repair in this pollen would be to use 5-bromodeoxyuridine or deoxyuridine instead of thymidine to label repaired DNA. The results show that pollen has the transport systems necessary to take up pyrimidine nucleosides from Petunia styles, where it is known that the concentration of free nucleosides increase after pollination.

Journal Article↗
PubMed1985

Acromegaly.

Explore the source record for details and available documents.

Acromegaly↗
PubMed1984

Colon carcinoma and diabetes mellitus.

A significantly increased occurrence of overt diabetes mellitus was found among colon or rectal carcinoma patients by comparison with that found among lung carcinoma or hip fracture populations in two hospitals.

Adolescent↗
PubMed1984

Divergent transport mechanisms for pyrimidine nucleosides in petunia pollen.

Petunia hybrida pollen exhibits divergent transport mechanisms for pyrimidine nucleosides. Uridine and cytidine show all the properties of being actively transported, a nucleoside transport mechanism not hitherto reported in plant cells. Contrasting with this, thymidine transport has the properties of a nonactive, carrier-mediated system. Reasons for these different mechanisms are considered to lie in the high demand for uridine and cytidine, obtained perhaps from stylar tissue, for the biosynthetic reactions of the pollen tube, while thymidine demand is lower due to the absence of DNA replication in germinating Petunia pollen.

Journal Article↗
PubMed1984

Pediatric oncology group utilization of immunologic markers in the designation of acute lymphocytic leukemia subgroups: influence on treatment response.

The clinical application of blast cell immunophenotype testing is important in childhood ALL for the following reasons. (1) Knowledge of the immunologic group is important in predicting prognosis. Prognostic grouping may prove to be accomplished best by using a combination of traditional risk factors and immunologic phenotyping. However, definition of traditional risk factors may vary within the immunologic groups of ALL. (2) In assessing the relative effectiveness of different treatment regimens for children with ALL it is important to make comparisons among patients within the same major immunologic groups of ALL. (3) Identification of specific immunologic groups of patients within ALL may help in designing therapy for each group. The POG has already made preliminary attempts in this direction for T-ALL and B-ALL. However, leukemia species-specific therapy is still only a long-range goal. Laboratory research must endeavor to identify additional biologic characteristics peculiar to each major immunologic group of ALL. These characteristics may dictate therapeutic maneuvers in the future.

Antigens, Neoplasm↗
PubMed1983

A single gene encodes multiple neuropeptides mediating a stereotyped behavior.

Egg laying in Aplysia is characterized by a stereotyped behavioral array which is mediated by several neuroactive peptides. We have sequenced two genes encoding the A and B peptides thought to initiate the egg-laying process, as well as a gene encoding egg-laying hormone (ELH) which directly mediates the behavioral array. The three genes share 90% sequence homology and are representatives of a small multigene family. Each gene encodes a protein precursor in which the active peptides are flanked by internal cleavage sites providing the potential to generate multiple small peptides. Each of the three genes consists of sequences homologous to A or B peptide as well as ELH. Although these genes share significant nucleotide homology, they have diverged such that different member genes express functionally related but nonoverlapping sets of neuroactive peptides in different tissues.

Animals↗
PubMed1983

Dominant spinocerebellar ataxia: genetic counseling.

Dominantly inherited spinocerebellar ataxia (OPCA 1) poses a particular problem for genetic counseling due to late age of onset. Liability for disease using observed age of onset can be combined with HLA linkage data to provide revised estimates of risk for affection. Where data is informative, certain combinations may yield estimates which improve so rapidly with age that postponement of childbearing may become a strong consideration as an option.

Adolescent↗
PubMed1982

Regional enteritis and HLA concordance in multiple siblings.

A familial predisposition to ulcerative colitis and Crohn's disease is well established, and linkage of a susceptibility gene to the HLA gene locus has been postulated. We report here a family of five children, at least four and probably all five of whom have Crohn's disease. HLA studies of four of the five showed three with the same paternal haplotypes (A2, B44), all four with the same maternal haplotypes (A30, B17), and three of the four to be HLA identical. combination of this data with four studies in the literature shows an excess of shared haplotypes among sibling pairs with disease, but the excess does not reach statistical significance. Thus, although the data shows a trend, Crohn's disease susceptibility linkage to the HLA gene locus is still unsettled. Lymphocytotoxic antibody was present in two of the four children but in neither parent.

Adolescent↗
PubMed1982

A family of genes that codes for ELH, a neuropeptide eliciting a stereotyped pattern of behavior in Aplysia.

We describe a particularly advantageous experimental system for studying gene structure, expression and modulation in the nervous system. In the marine mollusc Aplysia, the bag cells, two discrete clusters of neurons, secrete a peptide of known behavioral function. This neuroactive peptide, egg-laying hormone (ELH), produces a characteristic and stereotypic behavioral repertoire, consisting first of a cessation of walking and inhibition of feeding, followed by head waving and egg laying. We have cloned the genes encoding ELH and characterized their organization and expression. At least five distinct genes for ELH exist within the chromosome. Sequence analysis of one recombinant clone unambiguously identifies a contiguous stretch of nucleotides that encodes the 36 amino acids of ELH. Transcription of this small multigene family results in the expression of at least five distinct RNA transcripts encoding ELH. The pattern of transcripts differs strikingly in different tissues: bag cells express three distinct mRNA species, whereas the atrial gland, a secretory reproductive gland, expresses two distinct mRNAs. Several other neuronal and nonneuronal tissues do not express ELH RNA. In vitro these mRNAs produce a series of long polypeptide precursors that must be processed to generate the active ELH peptide. This processing event is likely to generate several additional neuroactive peptides. Thus the same peptide, ELH, may be released in association with different combinations of other neuroactive peptides. The concept of combinatorial sets of neuropeptides, each bearing one overlapping peptide ELH, and each directing a differing pattern of behavior, greatly expands the information potential of a small set of genes.

Animals↗
PubMed1982

Progression rate and age at onset are related in autosomal dominant neurologic diseases.

We found that the rate of progression of two adult hereditary neurologic disorders (dominant ataxia and Huntington disease) correlated inversely with the age at onset. The earlier the onset, the more rapid the course; the later the onset, the slower the course. Alzheimer disease/senile dementia followed a similar pattern. The rate of progression of a nonhereditary progressive neurologic disorder, ALS, showed the opposite trend.

Adolescent↗