PubMed Health⌕ Search

Biomedical subjects

J English

Publications and source records attributed to J English.

At least 19 recordsLinked to original sources
PubMed1992

Effective vectors for transformation, expression of heterologous genes, and assaying transposon excision in transgenic plants.

Progress in plant molecular biology has depended heavily on the availability of effective vectors for plant cell transformation and heterologous expression. In this paper we describe the structures of a wide array of plasmids which have proved extremely effective in (a) plant transformation, (b) expression of heterologous genes and (c) assaying the activity of transposons in transgenic plants. Constructs that confer resistance to kanamycin, hygromycin, streptomycin, spectinomycin and phosphinotricin, or that confer beta-glucuronidase (GUS) gene expression are presented. Binary vector constructs that carry polylinkers of the pUC and Bluescript types are also described. Plasmids that permit the expression of any heterologous reading frame from either nopaline synthase (nos) or octopine synthase (ocs) promoters, as well as the cauliflower mosaic virus 35S promoter, using either the nopaline synthase or octopine synthase 3' polyadenylation sequences, are presented. These constructs permit a choice of orientation of the resulting transgene of interest, relative to the orientation of the selection marker gene. Most of the plasmids described here are publicly available.

Amino Acid Oxidoreductases↗
PubMed1992

Instructing facilitators to support the communication of people who use augmentative communication systems.

A single-subject multiple-baseline design, replicated across three dyads, was used to examine the efficacy of instructing facilitators (i.e, significant others) to promote communication with people who use augmentative and alternative communication (AAC) systems. Facilitators were instructed in four 1-hour sessions to decrease their conversational control and provide more opportunities for the participants using AAC systems to communicate. Following instruction, facilitators decreased their rates of turn-taking and initiations and increased the proportion of turns that were responsive. Participants using AAC systems increased the frequency of their initiations. Following intervention, turn-taking and initiation patterns in the dyads were more reciprocal. Generalization occurred to the natural environment. Results suggest that facilitator instruction is an effective and efficient means of promoting greater participation in daily interactions by people who use AAC systems.

Adolescent↗
PubMed1992

The embryonically active gene, unkempt, of Drosophila encodes a Cys3His finger protein.

The unkempt gene of Drosophila encodes a set of embryonic RNAs, which are abundant during early stages of embryogenesis and are present ubiquitously in most somatic tissues from the syncytial embryo through stage 15 of embryogenesis. Expression of unkempt RNAs becomes restricted predominantly to the central nervous system in stages 16 and early 17. Analysis of cDNAs from this locus reveals the presence of five Cys3His fingers in the protein product. Isolation and analysis of mutations affecting the unkempt gene, including complete deletions of this gene, indicate that there is no zygotic requirement for unkempt during embryogenesis, presumably due to the contribution of maternally supplied RNA, although the gene is essential during post-embryonic development.

Amino Acid Sequence↗
PubMed1991

Delayed sleep phase syndrome response to melatonin.

The actions of melatonin on the sleep-wake cycle were investigated by means of a randomised, double-blind, placebo-controlled trial in 8 subjects with a delayed sleep phase syndrome attending a sleep disorders clinic. In randomised order the subjects received placebo or melatonin 5 mg daily for 4 weeks with a 1 week washout period between the treatments. Drug or placebo was given at 2200 h, 5 h before the mean time of sleep onset determined by pretrial sleep logs. In all 8 subjects sleep onset time (mean advance 82 [range 19-124] min; p less than 0.01) and wake time (117 [10-187] min; p less than 0.01) were significantly earlier during melatonin treatment than during placebo. Mean total sleep time was slightly less on melatonin (8 h 12 min) than on placebo (8 h 46 min). Alertness acrophase calculated from the subjects' ratings of alertness made every 2 h while awake was unaltered. Melatonin may act as a phase-setter for sleep-wake cycles in subjects with a delayed sleep phase syndrome.

Administration, Oral↗
PubMed1991

The concentration of insulin-like growth factor-I and insulin-like growth factor-binding protein-1 in human umbilical cord serum at delivery: relation to fetal weight.

Serum levels of insulin-like growth factor-I (IGF-I) and insulin-like growth factor-binding protein-1 (IGFBP-1) have been determined by radioimmunoassay in the maternal circulation (n = 91) and in the umbilical artery (n = 56) and vein (n = 90) of man. In both the umbilical artery and vein, the concentration of serum IGF-I showed an inverse correlation with birthweight (P less than 0.005 and P less than 0.001 respectively); the mean serum IGF-I levels in the small-for-gestational-age (SGA) group were significantly higher than those in average-for-gestational-age (AGA) neonates (P less than 0.01 and P less than 0.001 respectively). However, maternal serum IGF-I showed no association with birthweight and there was no significant difference between the SGA and AGA groups. These observations imply that the production of IGF-I in the maternal and fetal compartments is independent and that there is unlikely to be transfer of IGF-I across the placenta. Serum IGFBP-1 levels in both maternal and umbilical cord blood (artery and vein) showed an inverse relation to birthweight (P less than 0.001, P less than 0.005 and P less than 0.001 respectively). Increased IGFBP-1 levels in the umbilical artery and vein were observed in the SGA group. These findings suggest that IGFBP-1 might inhibit the action of IGF-I in both the maternal and the fetal compartments and that the rise in IGFBP-1 could be a primary factor in retardation of fetal growth. Alternatively, circulating IGF-I and IGFBP-1 levels may only be a secondary reflection of local tissue events involved in fetal growth.

Birth Weight↗
PubMed1990

Quantitative structure-activity relationships within a series of melatonin analogs and related indolealkylamines.

The results of molecular orbital calculations by the complete neglect of differential overlap, 2nd version on 10 indolealkylamines and amides related to melatonin are reported. Quantitative structure-activity relationships have been derived by regression analysis of electronic structural parameters and biological data in the form of melatonin receptor affinities. On the basis of these results, together with electrostatic potential energy calculations, a possible receptor binding site model is proposed.

Binding Sites↗
PubMed1989

Chromosome-breaking structure in maize involving a fractured Ac element.

Chromosome breakage in maize can result from an interaction between certain transposable elements. When an Ac (Activator) element and a state I Ds (Dissociation) element are present together in the genome, either linked or unlinked, breaks occur regularly at the locus of the Ds element. We show here that breaks occur with high frequency at or near the locus of a structure consisting of a 2.5-kilobase (kb) terminally deleted or fractured Ac element very tightly linked to a second, intact 4.6-kb Ac element. This structure has the features of a macrotransposon and may behave like one. Loss of the tight linkage abolishes chromosome breakage. A model based on transposition of the macrotransposon is proposed to explain the chromosome-breaking properties of Ac and Ds.

Alleles↗
PubMed1989

Plasma prolactin concentrations in pinealectomized ewes receiving melatonin treatment and in pineal intact ewes maintained under a non-24-hour photoperiod.

We have investigated the profiles of prolactin secretion in relation to onset of breeding activity in Suffolk-Cross ewes with artificially modified melatonin rhythms. With treatments commencing in midsummer, groups of ewes were 1) subjected to a 8L:16D photoperiod, 2) maintained under a "short" (6L:16D) photoperiod repeated over a 22-h cycle that induces an elevation in plasma melatonin that does not endure for the entire dark phase, 3) pinealectomized (pnx) to abolish plasma melatonin levels, and 4) pinealectomized and treated with a melatonin implant (subcutaneous) to provide a constant (no 24-h rhythm) elevation in plasma melatonin. The onset of breeding activity was significantly advanced in both the 8L:16D and pnx/implant groups compared to the 6L:16D and untreated pnx ewes. The two latter groups displayed a normal timing in seasonal breeding activity. Low and high plasma prolactin levels corresponded with short and long photoperiods during both the 24 and 22-h cycles. There was no clearcut "seasonal" rhythm in plasma prolactin in either of the pnx groups. A clear differentiation was seen between reproductive response and prolactin response, particularly in the case of ewes monitored on 22-h cycles of short photoperiod.

Animals↗
PubMed1989

Studies of renal function in animals chronically treated with apomorphine.

Based on the observation that orally administered apomorphine may induce nephrotoxicity, we studied the renal effects of a two-week subcutaneous infusion of apomorphine in rats. Drug-treated rats did not exhibit any change in renal cortical uptake of an organic cation (tetraethyl ammonium), organic anion (para-hippuric acid), creatinine clearance, or fractional excretion of sodium and potassium. Renal histology showed no change specific to drug. A small increase in urinary N-acetylglucosaminidase, a tubular enzyme, was measured but a second tubular enzyme showed no change. We conclude that parenterally administered apomorphine is not associated with renal toxicity.

Animals↗
PubMed1988

The frequency of transposition of the maize element Activator is not affected by an adjacent deletion.

The maize mutable allele bz-m2 (Ac), which arose from insertion of the 4.6 kb Ac element in the bz (bronze) locus, gives rise to stable bz (bz-s) derivatives that retain an active Ac element closely linked to bz. In the derivative bz-s: 2114 (Ac), the Ac element is recombinationally inseparable from bz and transposes to unlinked sites at a frequency similar to that in the progenitor allele bz-m2 (Ac). Both alleles have been cloned and sequenced. The bz-s: 2114 (Ac) mutation retains Ac at the original site of insertion, but has lost a 789 bp upstream bz sequence adjacent to the insertion, hence the stable phenotype. The 8 bp target site direct repeat flanking the Ac insertion in the bz-m2 (Ac) allele is deleted in bz-s: 2114 (Ac), yet the Ac element is not impaired in its ability to transpose. The only functional Ac element in bz-s: 2114 (Ac) is the one at the bz locus: in second-cycle derivatives without Ac activity, the loss of Ac activity correlated with the physical loss of the Ac element from the bz locus. The deletion endpoint in bz-s: 2114 (Ac) corresponds exactly with the site of insertion of a Ds element in a different bz mutation, which suggests that there may be preferred integration sites in the genome and that the deletion originated as the consequence of an abortive transposition event. Finally, we report two errors in the published Ac sequence.

Alleles↗
PubMed1988

The 'difficult' elderly patient: adjustment or maladjustment?

In this study, simultaneous triangulation was used to explore the problem of the 'difficult' patient. Ethnoscience was used to describe the perceptions of nurses about the types of difficult patients, ethnographic interviews with difficult patients were used to elicit information about the patients' perspective of the hospitalization experience, and a content analysis of 42 vignettes published in nursing magazines describing difficult patients and the resolution of the problem provided the third perspective. Data from these three sources were integrated to develop an explanatory model for the difficult behaviour. The antecedent is patients' unmet expectations; the patients' behavioural response is an attempt to maintain personal control of the experience of hospitalization; and, frequently, the nurses' response to regain control exacerbates the situation.

Adaptation, Psychological↗
PubMed1988

How does melatonin control seasonal reproductive cycles?

The pineal gland is essential for the perception of photoperiod change in many species. Information about photoperiod length is conveyed through pineal secretion of the methoxyindole melatonin. Melatonin, suitably administered in physiological quantities is equipotent with artificial photoperiod in the induction of photoperiodic responses. Most experimental work suggests that it is the duration of high night time melatonin secretion (positively correlated with the length of the natural or artificial dark phase) which conveys the photoperiodic signal. Continuous release implants induce short day effects in ewes, entirely comparable to daily feeding of melatonin or short photoperiod. A minimum duration of secretion rather than a specific duration is therefore probably critical to short day effects. There appears to be a seasonal variation in sensitivity to short day melatonin effects (induction of early oestrus) which can be shifted to an earlier time of year following one oestrus advance the previous year. Short duration melatonin is read as a long day even secreted with 22 hour periodicity, suggesting a lack of circadian variation in sensitivity to melatonin.

Animals↗
PubMed1988

Pineal and ovarian response to 22- and 24-h days in the ewe.

Melatonin secretion in ewes was entrained by 22-h light-dark cycles whether of long (16L:6D) or short (6L:16D) photoperiod. In photoperiods of 6L:16D, a phase-delay of melatonin secretion was evident, leading to a dark-phase duration shorter than that found in 8L:16D. Early onset of estrus was induced in anestrous ewes kept in 8L:16D, but not 6L:16D, from 22 July compared to controls in natural light. In photoperiods of 16L:6D, the melatonin profile corresponded precisely to the dark phase. Early offset of estrus was induced in estrous ewes kept in both 18L:6D and 16L:6D from 18 December compared to controls in natural light. Thus, when the duration of melatonin secretion was appropriate to the long photoperiod (16L:6D), but with a constantly changing phase position, a long-day reproductive response was found. Activity-rest cycles were not entrained by 16L:6D; thus the synchronization of melatonin and activity-rest cycles does not appear to be essential for the induction of a long-day reproductive response. These results support the hypothesis that the duration, not the circadian-phase position, of melatonin is critical to the induction of photoperiodic effects.

Animals↗
PubMed1988

Effect of animal sex on experimental ciclosporin nephrotoxicity.

UNLABELLED: Experimental ciclosporin (CSA) nephrotoxicity is reported to be more severe in male versus female rodents. To investigate these sex differences further, groups of male and female Sprague-Dawley rats were pair fed and given either CSA 50 mg/kg or olive oil vehicle by gavage daily for 5 days. Both groups of treated animals showed azotemia and depression of CIn but there were no sex differences. CSA levels were 5,820 ng/ml in females and 6,480 ng/ml in males (p = NS). Although CSA did not produce enzymuria in either sex, females showed more extensive proximal tubular cell vacuolization. CONCLUSION: Female Sprague-Dawley rats are equally as susceptible to CSA nephrotoxicity as males. Strain differences or experimental design may account for apparently conflicting results in the literature.

Animals↗
PubMed1988

Chronic tubulointerstitial nephritis and renal insufficiency associated with long-term "subtherapeutic" gentamicin.

To determine whether long-term "subtherapeutic" concentrations of aminoglycoside produce chronic tubulointerstitial nephropathy, Fisher rats were given gentamicin, 20 mg/kg/day, for up to 6 months via indwelling osmotic infusion pumps. Studies included renal histology, autoradiographic quantitation of renal cell tritiated thymidine uptake, renal function and renal cortical gentamicin assay. Acute proximal tubular injury, without tubular necrosis, followed by recovery, occurred during the first month. Subsequently only mild, nonprogressive tubulointerstitial changes and a twofold increase in tubular cell turnover were observed. Inulin clearance fell more than 50% during the 6 months of treatment compared with 10% in age-matched controls. Serum creatinine and creatinine clearance overestimated glomerular filtration rate during treatment and did not distinguish treated animals from controls. During the month after 6 months of gentamicin, tubular microcystic changes and active tubulointerstitial nephritis developed, with a continued fall in inulin clearance. In summary, gentamicin, in "subtherapeutic" doses, produces mild chronic tubulointerstitial nephritis with progressive renal failure. Cessation of treatment is associated with microcystic and inflammatory changes, suggesting that the renal response to tubular injury can be dissociated from the amount of toxin in the renal cortex. Keeping serum aminoglycoside levels below accepted therapeutic range for 6 months did not preclude nephrotoxicity.

Animals↗