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Biomedical subjects

G B Collins

Publications and source records attributed to G B Collins.

At least 19 recordsLinked to original sources
PubMed2001

Overexpression of the Arabidopsis thaliana MinD1 gene alters chloroplast size and number in transgenic tobacco plants.

The Arabidopsis thaliana (L.) Heynh. minD gene (AtMinD1) was isolated and constitutively expressed in tobacco (Nicotiana tabacum L.) plants using the CaMV 35S promoter. Confocal and electron-microscopic analysis of the AtMinD1 transgenic tobacco lines revealed that the chloroplasts were abnormally large and fewer in number compared with wild-type tobacco plants. The abnormal chloroplasts were less prevalent in guard cells than in mesophyll cells. Chloroplast and nuclear gene expression was not significantly different in AtMinD1-overexpressing plants relative to wild-type tobacco plants. Chloroplast DNA copy number was not affected, based on the relative level of the rbcL gene in transgenic plants. Transgenic tobacco plants constitutively overexpressing AtMinD1 were completely normal phenotypically with respect to growth and development, and also displayed normal photosynthetic electron transport rates. These results show that the Arabidopsis MinD1 gene also functions in a heterologous system and confirm the role of the MinD protein in regulation of chloroplast division.

Arabidopsis↗
PubMed1998

Co-ordinated expression of multiple enzymes in different subcellular compartments in plants.

A gene expression system designed for coordinated expression of multiple genes in plants and their targeting to specified subcellular locations was tested. A series of genes encoding polyproteins containing the tobacco vein mottling virus (TVMV) Nla proteinase along with two other reporter genes (those encoding the Escherichia coli acetate kinase (ACK) and Tn9 chloramphenicol, acetyl transferase (CAT) enzymes) were assembled. The respective coding sequences of these genes were separated by a TVMV Nla proteinase recognition sequence. In addition, in some instances, chloroplast targeting information (a transit peptide (TP) from a pea rbcS gene) was incorporated into the polyprotein. We found that the Nla proteinase can be used to express, as individual polypeptides, the ACK and CAT proteins, and that these proteins retain enzymatic activity. Polyproteins with the structure TP-Nla-ACK-CAT or TP-ACK-CAT-Nla failed to yield chloroplast-localized ACK and CAT proteins, although the latter did give rise to a chloroplast-localized ACK-CAT polyprotein. These results indicate that the Nla proteinase acts in cis more rapidly than transport of proteins into the chloroplast, but that chloroplast localization can take place before complete processing of the polyprotein. Polyproteins with the structures ACK-Nla-TP-CAT and TP-ACK-Nla-TP-CAT yielded appropriately processed and targeted ACK and CAT. Our results show that subcellular localization signals can be effectively recognized in the context of a polyprotein, and they suggest an appropriate strategy for simultaneous engineering of multiple subcellular compartments in plants.

Amino Acid Sequence↗
PubMed1998

In vitro interactions between a potyvirus-encoded, genome-linked protein and RNA-dependent RNA polymerase.

Recent studies have shown that potyvirus VPg/ proteinases and RNA-dependent RNA polymerases are capable of protein-protein interactions in yeast cells. We have extended these studies in vitro. We found that tobacco vein mottling virus (TVMV) VPg is retained on glutathione-Sepharose matrices if co-incubated with a glutathione S-transferase (GST)-NIb fusion protein, but not with GST, which is suggestive of a direct physical interaction between these two proteins. However, a mutation in the VPg (Y1860S) that eliminates virus infectivity and the interaction in yeast cells had little effect on the in vitro interaction. We also found that the TVMV VPg and NIa proteins are capable of stimulating the polymerase activity of the NIb protein. Since this stimulatory activity is retained when the proteinase domain of the NIa is removed, we conclude that the VPg is the moiety responsible for the stimulation of polymerase activity. As with the interaction revealed by co-purification, the Y1860S mutation had little or no effect on the stimulation of polymerase activity. Moreover, the VPg was able to stimulate a mutant NIb with an altered 'GDD' motif. Our studies thus provide two lines of evidence indicative of in vitro interactions between the TVMV VPg and NIb proteins.

Amino Acid Sequence↗
PubMed1998

New hope for impaired physicians: helping the physician while protecting patients.

The medical profession has developed a greater awareness of the problem of substance abuse among physicians, and has responded by setting programs to confront impaired physicians about their problem so that they can overcome their resistance to treatment. Nonetheless, the most effective strategy is prevention: instilling physicians-in-training with a more cautious attitude towards drug and alcohol use.

Alcoholism↗
PubMed1994

Expression of desiccation-induced and lipoxygenase genes during the transition from the maturation to the germination phases in soybean somatic embryos.

Transitions between developmental programs during plant embryogenesis are usually characterized by differential gene expression. Soybean (Glycine max (L.) Merr.) somatic embryos from embryogenic suspension cultures germinate poorly on a germination medium even after being grown on medium containing abscisic acid until developmental changes are induced by desiccation. The objectives of this study were to investigate: (i) the relationship between water loss and germination of somatic embryos, (ii) changes in desiccation-induced polypeptides, and (iii) the expression of maturation- and germination-associated genes during the transition from maturation to germination of soybean somatic embryos. The results revealed that partial drying of somatic embryos at 76% relative humidity for 96 h resulted in more than 90% germination. Germination frequency was correlated with the percent fresh weight loss of the somatic embryos. Polypeptides induced by desiccation were classified into three groups based on the tissues in which they were expressed and the inducing agents to which they responded. Desiccation-induced polypeptides decreased or became undetectable upon inhibition. The expression of a maturation-associated gene, Mat1, was induced in both cotyledons and hypocotyl/radicle tissues of somatic embryos after 72 h desiccation. The transcript for this gene increased in concert with water loss from the embryos. During maturation of somatic embryos, the expression of embryonic lipoxygenase genes was turned on. Desiccation alone did not directly induce expression of germination-associated lipoxygenase genes SC514 and LOXB2 in somatic embryos.(ABSTRACT TRUNCATED AT 250 WORDS)

Base Sequence↗
PubMed1993

Contemporary issues in the treatment of alcohol dependence.

Alcoholism treatment has certainly come of age since its inception with the founding of Alcoholics Anonymous in 1935. Although AA is a "fellowship" and is not considered "treatment" per se, the growth and proliferation of professional treatment programs has spawned a significant new sector in the health care industry, with a corresponding rise in health care cost. Because the social cost due to the destructiveness of alcoholism is enormous, however, treatment appears to be a cost beneficial investment for society, both in terms of dollars expended and in terms of the lessening of human misery. Inpatient and outpatient programs appear to be effective, but simplistic comparisons are to be avoided because their populations are frequently much different, with patients with poor prognosis indicators showing up more frequently in inpatient settings. Although outpatient treatment is undeniably cheaper initially, appreciable long-term savings may not be realized because of the greater tendency for recidivism in outpatient-treated groups. Taken as a whole, studies of treatment outcome and cost effectiveness support the view that contemporary alcoholism treatment should provide multiple levels of care, with appropriate matching of patients, depending on severity and various demographic factors. This matching may be difficult to realize in actual practice because of the wide variability among alcoholic patients. Although some patient-treatment matching criteria are now in use by insurance carriers and treatment providers, the long-term efficacy of these criteria have not been tested adequately. In the end, it may evolve that the best determinant of assignment to a particular treatment level or modality might best be done by a responsible clinician exercising good judgment based on experience and training. Appropriate legal and financial accountability for this decision should be based on standards of reasonableness, consistent with criteria used in the treatment of other medical and surgical conditions. The alcoholism clinician is performing a valuable service to humanity and to society. Social policies should support this effort by making available appropriate facilities and programs for treatment, and by promoting access through destigmatization and favorable payment and reimbursement systems.

Aftercare↗
PubMed1992

Peanut stunt virus satellite RNA: analysis of sequences that affect symptom attenuation in tobacco.

The V-satellite RNA (V-satRNA) of peanut stunt virus (PSV) has no effect on symptoms produced in tobacco by PSV. In contast, the G-satRNA induced complete or nearly complete suppression of systemic symptom development. Because G-satRNA differs from V-satRNA in only five nucleotide positions, these two satRNAs provide excellent material for investigating the molecular basis of satRNA-mediated symptom attenuation. For this purpose, we constructed transcription vectors containing full-length cDNA clones from which infectious RNA transcripts can be synthesized in vitro, and produced chimeric and mutant satRNA molecules. Although an A----C substitution at position 362 of the V-satRNA molecule delayed systemic symptom development and reduced symptom severity, changes at both nucleotide positions 226 (C----U) and 362 (A----C) of V-satRNA were required for suppression of systemic symptom development. Our results are consistent with the idea that PSV satRNAs are noncoding molecules that exert their biological activities by directly interacting with host/viral components.

Base Sequence↗
PubMed1992

Fatty acid alteration by a delta 9 desaturase in transgenic tobacco tissue.

Nicotiana tabacum tissue was transformed with a rat stearyl-CoA desaturase gene. Gas chromatographic analysis showed an increase in monounsaturated 16 and 18 carbon fatty acids in selected transformed calli and leaves. Fractionation of lipid classes indicated that palmitoleic acid was found in the phosphatidylcholine fraction of desaturase-transformed leaves, but not in leaves transformed with vector sequences. Plant transformation was verified by polymerase chain reaction (PCR) amplification of total leaf DNA.

Animals↗
PubMed1992

Neuroendocrine, fluid balance, and thirst responses to alcohol in alcoholics.

This study simultaneously evaluated multiple circulating neurohormones, osmolality, thirst, and fluid balance in eight actively drinking, alcoholic males and seven controls before and 12 hr after an ethanol challenge. Basal levels of serum osmolality and thirst were significantly higher in alcoholics compared with controls, yet actively drinking alcoholics at the start of the study had normal vasopressin (AVP) levels, plasma angiotensin II (Ang II), plasma renin activity, plasma aldosterone (Aldo), and plasma catecholamines. In response to ethanol, serum osmolalities rose significantly higher while plasma AVP levels became significantly suppressed in alcoholics. After the ethanol stimulus, plasma Ang II levels of alcoholics were significantly higher than those of controls at 11 AM (12.15 +/- 4.49 vs. 1.83 +/- 0.6 pg/ml, p less than 0.02) and 12 noon (14.93 +/- 6.81 vs. 1.37 +/- 0.17 pg/ml, p less than 0.04). Neither plasma renin activity nor Aldo changed in accordance with the elevated plasma Ang II in alcoholics. Diuresis in the alcoholics, assessed by the sum of urine output following the challenge dose, was significantly less than that of controls. Thirst scores and fluid intakes after the ethanol challenge did not differ between alcoholics and controls. The lack of an Ang II-mediated increase in plasma Aldo or thirst response suggests that ethanol may have a specific blunting effect on Ang II receptors. This study demonstrates that ethanol can be used as a provocative test in chronic alcoholics to uncover aberrant hormonal responses for two systems, namely, Ang II and AVP.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Effects of exogenous auxins on expression of lipoxygenases in cultured soybean embryos.

The expression of lipoxygenases (LOXs) is known to be developmentally regulated in soybeans (Glycine max. [L.] Merr.). Hormones have been firmly established as being involved in the growth and developmental processes of a number of plant species. Correlation between the expression of LOXs and the development and germination of soybean embryos suggests that plant hormones may affect the expression of LOXs. The present studies were conducted to investigate the effects of exogenous auxins on the expression of LOX isozymes and LOX activities in cultured cotyledon tissues of immature soybean seeds. The results revealed that at least one of the more acidic nonembryo LOX isozymes was induced by either alpha-naphthaleneacetic acid or indoleacetic acid but not by 2,4-dichlorophenoxyacetic acid after 4 days' exposure. Levels of LOX-1, -2, and -3 proteins and activities were significantly decreased by 2,4-dichlorophenoxyacetic acid 10 days after explanting. S1 analysis showed that embryo LOX messenger RNAs were detectable in the tissues treated with each of the auxins. The reduced levels of the embryo LOX proteins may, therefore, be regulated at the levels of translation, posttranslational modification, or degradation. The more acidic isozymes induced by alpha-naphthaleneacetic acid showed enzymatic activity and shared the same molecular mass and isoelectric point values as the germination-associated LOX isozymes found in hypocotyls and radicles, suggesting that those LOXs are involved in germination competency of soybean embryos.

Journal Article↗
PubMed1987

Dental management of the recovered chemically dependent patient.

People who are recovered from chemical dependency are frequently seen in dental practice. They have special needs, especially in pain management. Understanding chemical dependency and establishing a good pretreatment rapport with the patient will assist the dentist in reducing the need for postoperative analgesics. The practitioner should rely highly on nonsteroidal anti-inflammatory agents as primary analgesics for these patients. Opiate derivatives, tranquilizers, sedatives, cough syrups, and general anesthetics should be avoided.

Alcoholism↗