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K Kirby

Publications and source records attributed to K Kirby.

At least 19 recordsLinked to original sources
PubMed1998

Transgenic analysis of the cSOD-null phenotypic syndrome in Drosophila.

Cu-Zn superoxide dismutase (cSOD) is an enzyme of critical importance for the inactivation of superoxide radicals generated by cellular metabolic processes. A phenotypic syndrome has been characterized for homozygotes for a null mutation of the Drosophila cSOD gene, many features of which may be relevant to current studies of cSOD mutations in mammals. However, it was possible that some of the features of this syndrome were at least partially attributable to genetic background differences between control and mutant strains. The results reported in this paper document that the previously described features of the cSOD-null phenotype, namely (i) adult sensitivity to paraquat, (ii) male sterility, (iii) female semisterility, (iv) adult life-span reduction, (v) adult hyperoxia sensitivity, (vi) larval radiation sensitivity, and (vii) developmental sensitivity to glutathione depletion, are all rescued by a cSOD+ transgene in a controlled cSOD-null genetic background. This clearly confirms that the phenotype is largely attributable to the cSOD mutation per se. We describe two new features of the cSOD-null phenotype, namely (viii) adult sensitivity to glutathione depletion, and (ix) adult sensitivity to ionizing radiation, which are ameliorated by the cSOD+ transgene. The distinct sensitivity of cSOD-deficient individuals, and the uniform resistance of the cSOD+ control strains, clearly establish the requirement for cSOD in protection against intrinsic and applied oxygen stress and set the stage for tissue-specific expression studies with the goal of elucidating the critical target(s) of damage in cSOD-deficient animals.

Animals↗
PubMed1997

The manganese superoxide dismutase gene of Drosophila: structure, expression, and evidence for regulation by MAP kinase.

The gene encoding manganese superoxide dismutase (MnSOD) from Drosophila melanogaster has been isolated and its expression has been studied. In contrast to several mammalian MnSOD genes, the Drosophila gene contains a single intron and is transcribed into a single 0.8-kb transcript. Whole-mount in situ hybridization reveals extensive transcript accumulation in ovarian nurse cells and a heavy maternal contribution to the early embryo. Larval imaginal discs are enriched with MnSOD transcripts relative to other larval tissues, further suggesting a possible relationship between high MnSOD expression and mitotic activity. The 5'-upstream region contains several well-known regulatory elements including metal response, antioxidant response, and xenobiotic response elements (MRE, ARE, and XRE, respectively), sites for activator protein-1 (AP-1), nuclear factor-kappaB (NF-kappaB), adenosine 3',5'-cyclic monophosphate regulator binding element factor (CREB), as well as classic TATA and CAAT boxes. That MnSOD expression in Drosophila is regulated in part by the transcription factor AP-1 via the MAP kinase signal transduction pathway is suggested by experiments which show that a hypomorphic mutation of the MAP kinase-encoding rolled gene substantially reduces levels of MnSOD transcripts and correlates with reduced resistance to oxidative stress in rolled mutants.

Animals↗
PubMed1996

A plasmid rescue to investigate mutagenesis in transgenic D. melanogaster.

We present a plasmid rescue from transgenic Drosophila to study spontaneous and mutagen-induced mutations in vivo. Transgenic Drosophila lines were established by transformation with a shuttle vector containing the bacterial lacZ gene as a target for mutagenesis. The target gene can be recovered into bacteria by restriction endonuclease treatment of total genomic DNA, followed by ligation of the recircularized shuttle vectors. The resulting circular plasmids are then transformed back into E. coli lacZ- mutants, where the activity of the lacZ genes is scored on the induction substrate X-Gal. The number of inactivated versus intact lacZ genes directly indicates the mutation frequency. By the described target gene rescue procedure up to 5000 lacZ gene copies can be rescued from one fly routinely. Spontaneous background mutation rates using this system are 2.6 +/- 0.6 x 10(-4). Treatment of larvae with ethylnitrosourea (ENU) resulted in a dose-dependent increase of the mutation frequency to 4.8 +/- 0.6 x 10(-4) for 0.5 mM and 6.9 +/- 1.2 x 10(-4) for 1 mM ENU, respectively.

Animals↗
PubMed1995

Subunit-destabilizing mutations in Drosophila copper/zinc superoxide dismutase: neuropathology and a model of dimer dysequilibrium.

Mutations in Cu/Zn superoxide dismutase (SOD), a hallmark of familial amyotrophic lateral sclerosis (FALS) in humans, are shown here to confer striking neuropathology in Drosophila. Heterozygotes with one wild-type and one deleted SOD allele retain the expected 50% of normal activity for this dimeric enzyme. However, heterozygotes with one wild-type and one missense SOD allele show lesser SOD activities, ranging from 37% for a heterozygote carrying a missense mutation predicted from structural models to destabilize the dimer interface, to an average of 13% for several heterozygotes carrying missense mutations predicted to destabilize the subunit fold. Genetic and biochemical evidence suggests a model of dimer dysequilibrium whereby SOD activity in missense heterozygotes is reduced through entrapment of wild-type subunits into unstable or enzymatically inactive heterodimers. This dramatic impairment of the activity of wild-type subunits in vivo has implications for our understanding of FALS and for possible therapeutic strategies.

Amino Acid Sequence↗
PubMed1995

Fluoxetine is ineffective for treatment of cocaine dependence or concurrent opiate and cocaine dependence: two placebo-controlled double-blind trials.

Cocaine dependence has proved difficult to treat, whether occurring alone or in combination with opiate dependence. No medication has been demonstrated to be uniquely effective. Fluoxetine was examined as a candidate in two randomized, double-blind, placebo-controlled trials, one with cocaine-dependent patients (study 1) and the other with patients both cocaine and opiate dependent (study 2). It was selected for known specific action, antidepressant effects, minimum side effects, and data showing reduced cocaine effect and self-administration. Clinic visit frequency requirement, a variable with implications for treatment and cost, was also examined in study 1. A total of 228 patients in study 1 and 21 patients in study 2 completed consent and intake procedures. Patients with serious medical or DSM-III-R diagnoses other than cocaine dependence (study 1) or opiate and cocaine dependence (study 2) were excluded. Study 1 patients were assigned to one of two visit frequency schedules (2 or 5 days/week) and one of three medication doses (0, 20, or 40 mg of fluoxetine/day). Study 2 patients received placebo or 20 mg of fluoxetine and 65 to 80 mg of methadone and attended the clinic 5 days/week. All patients participated in individual therapy sessions. Urine screens were conducted twice weekly. A fluoxetine dose response relationship emerged in study 1 for retention with groups from best to worst being placebo, 20 mg, and 40 mg. Dose effect order was the same for both visit conditions. Cocaine use persisted in all groups. The two visits/week condition was correlated with better retention than the five visits/week condition. A significant interaction emerged between intake urine and visit frequency; patients with benzoylecognine screens at intake used cocaine significantly less in the 5 days/week condition, while exhibiting no reduction in the 2 days/week condition. Patients cocaine positive at intake were better retained with infrequent visits. In study 2, a transient reduction in benzoylecognine-positive drug screens emerged for the fluoxetine group. These complementary studies demonstrate that fluoxetine is ineffective in reducing cocaine use or craving. Study 1 also points to setting conditions modulating treatment outcome.

Adult↗
PubMed1994

A manganese superoxide dismutase-encoding cDNA from Drosophila melanogaster.

A cDNA encoding manganese superoxide dismutase (MnSOD) has been cloned and sequenced from Drosophila melanogaster. This 805-bp complete cDNA carries a single open reading frame which specifies a deduced 217-amino-acid (aa) protein with an average identity of 60.8% with deduced MnSOD aa sequences from Caenorabditis elegans and humans.

Amino Acid Sequence↗
PubMed1994

Stimulation of locomotion in neonate rats by TRH analogue CG3703.

Thyrotropin releasing hormone (TRH) and its analogues have been shown to depolarise motoneurons and stimulate cyclical motor activities such as respiration and locomotion. It has been suggested that one of its roles might be modulation of neuronal membrane excitability to release intrinsic rhythmicity. The present experiments were designed to determine whether it would initiate locomotion in the neonate rat prior to the development of spontaneous walking. It was found that the TRH analogue CG3703 did activate locomotion in 3-day-old rat pups. Quantification of various gait parameters and study of spatiotemporal footfall patterns showed the gait to be indistinguishable from the spontaneous locomotion of older pups. Possible loci of action are discussed.

Animals↗
PubMed1994

Effect of sputum induction on arterial oxygen saturation and spirometry in HIV-infected patients.

We wanted to study the effect of sputum induction on forced expiratory volume in one second (FEV1) and on oxygen saturation in normal controls, asymptomatic human immunodeficiency virus (HIV)-seropositive individuals, and HIV-seropositive patients under investigation for suspected Pneumocystis carinii pneumonia (PCP). Over a five month period, sputum induction with ultrasonically nebulized 3% saline was performed on 110 HIV-seropositive patients with suspected PCP, 10 asymptomatic HIV-seropositive patients, and 15 normal controls. Oxygen saturation (peak, trough and change in oxygen saturation (delta O2)) was measured throughout the procedure using pulse oximetry, and these results compared with the chest radiograph and the final pulmonary diagnosis. In addition, the effect of sputum induction on FEV1 was measured in the 15 control subjects and 10 asymptomatic HIV-seropositive patients. Compared with bronchoalveolar lavage, sputum induction had a diagnostic sensitivity for PCP of 76%. Chest radiography was 79% sensitive, and had specificity of 83%. Patients with PCP had lower peak and trough oxygen saturation values compared with the non-PCP group (mean peak 95 vs 97%; mean trough 88 vs 91%), and greater falls in O2 saturation during the procedure (mean delta O2 7.6 vs 5.5%). One subject desaturated to 76%, requiring supplemental oxygen. Sputum induction caused significant but temporary falls in FEV1 both in control and HIV-seropositive groups (mean maximum fall in FEV1 10.4 vs 12.5%). We conclude that although sputum induction causes significant falls in oxygen saturation and FEV1, it remains sensitive and safe, and provides a useful alternative to bronchoscopy for the diagnosis of PCP.

AIDS-Related Opportunistic Infections↗
PubMed1990

Transfer and expression of an organophosphate insecticide-degrading gene from Pseudomonas in Drosophila melanogaster.

The organophosphorus acid hydrolases represent a distinct class of enzymes that catalyze the hydrolysis of a variety of organophosphate substrates, including many insecticides and their structural analogues. The plasmid-borne opd gene of Pseudomonas diminuta strain MG specifies an organophosphorus acid hydrolase, a phosphotriesterase, that has been well characterized and can hydrolyze a broad spectrum of insect and mammalian neurotoxins. The in situ functioning of this enzyme in the metabolism of organophosphates has been analyzed directly in insects by transferring the opd gene into embryos of Drosophila melanogaster by P element-mediated transformation. The chromosomal locations of this stably inherited transgenic locus differed from strain to strain and demonstrated various expressivity on the whole-insect basis. Transcriptional induction of opd in one of these strains under control of the Drosophila heat shock promoter, hsp70, resulted in the synthesis of stable active enzyme that accumulated to high levels with repeated induction. The heat shock-induced synthesis of organophosphorus acid hydrolases in transgenic flies conferred enhanced resistance to toxic paralysis by the organophosphate insecticide paraoxon.

Animals↗
PubMed1988

Prostatectomy in patients with bleeding disorders.

Urological surgery is becoming increasingly necessary in patients with acquired or congenital bleeding disorders. We reviewed the management of 10 such patients who required prostatectomy. The average age of the patients at operation was 65.7 years. Seven patients underwent transurethral prostatectomy and 3 underwent suprapubic prostatectomy. Postoperative bleeding occurred in 9 patients who required secondary procedures. Bleeding occurred an average of 13 days postoperatively. The mean hospital stay was 24 days. Partial thromboplastin time when determined was uniformly elevated in all patients preoperatively. The amount of factor and blood replacement is presented. Perioperative management of these patients is discussed in detail. A rational approach for the prevention of postoperative bleeding is presented.

Adult↗
PubMed1988

An inverse relationship between baseline fixed-interval response rate and the effects of a tandem response requirement.

Previous experiments examining the effects of adding a tandem fixed-ratio response requirement on fixed-interval schedule performance have reported inconsistent results. One variable that may account for such inconsistencies is the baseline response rate in the fixed-interval condition. This possibility was investigated in the present study. Rats were given histories with either interresponse times greater than 11 s or fixed-ratio 40 schedules of reinforcement, which engendered either relatively low or high rates of responding, respectively, in the subsequent fixed-interval condition. A tandem ratio response requirement (fixed-ratio 9) was then introduced. The effects of adding this tandem response requirement were inversely related to the baseline fixed-interval response rates; low rates of responding in the fixed-interval condition were markedly increased, whereas high rates of responding were relatively unaffected. This inverse relationship appears to be similar to the rate-dependent relations observed in behavioral pharmacology. These results may provide an explanation for the inconsistent findings reported in previous studies on tandem fixed-interval fixed-ratio schedules and suggest that principles of behavioral pharmacology research may be applicable to the study of the effects of nonpharmacological variables on schedule-controlled behavior.

Animals↗
PubMed1987

Hemiplegia and lower extremity amputation: double disability.

A retrospective study of 52 consecutive patients was conducted to determine the influence of certain factors on the ambulatory rehabilitation of patients with hemiplegia and lower extremity amputation. Factors studied included side of hemiplegia, laterality of disability, level of amputation, order of disability (amputation first or hemiplegia first), neuromuscular status, mental status, sex, age. The level of function was defined as independent, limited, or nonambulatory. Of 52 double-disability patients, thirty were fitted with a prosthesis. Eight patients attained independent prosthetic function while 16 patients were limited and six were nonambulatory. Factors such as ipsilateral BK amputation preceding hemiplegia, a good-to-fair neuromuscular status, and an intact mental status have been associated with better functional results. Although producing higher fitting rates, none of these factors has been found in the present study to be associated with statistically higher levels of ambulatory function. A good-to-fair neuromuscular status seemed to be the prime requisite for good ambulation with a prosthesis in a patient with the double disability of amputation and hemiplegia.

Aged↗
PubMed1986

Visceral nociception in developing rats.

Maturational changes in visceral nociception were measured in developing or adult rats challenged with hypertonic saline or acetylcholine. Chemically induced abdominal constrictions were absent in rats younger than 7 days of age, regardless of the dose of hypertonic saline or acetylcholine used. Age-related increases in the percent of animals responding, the number of abdominal constrictions emitted per responder, and total response duration occurred in animals 10-20 days of age, until adult-like patterns of responding were attained at the time of weaning. Additional changes in the percent animals responding, as well as in the frequency and total duration of abdominal constriction responses, were also seen in postweanling, but not in preweanling, animals. Five-day-old animals did emit audible vocalizations to the intraperitoneal insertion of a hypodermic needle, however, at a time when these animals failed to show observable responses to the noxious visceral stimuli. Hence, mechanisms mediating pain associated with intraperitoneal needle insertion may be functional during the first postnatal week, at a time when mechanisms mediating visceral pain appear to be immature. These differences may be caused by the differential maturation of sensory, neural, or motoric mechanisms important for hypodermic needle insertion versus visceral nociception.

Age Factors↗
PubMed1980

Canine hip dysplasia: breed effects.

This paper is a refinement of previous studies in that only suitably radiographed dogs were included in the data base. The rate of hip dysplasia varied widely by breed from five percent in siberian huskies to eighty-three percent in english bulldogs. There was a significant difference in the prevalence of dysplasia within at least two breeds; golden retrievers and old english sheepdogs. Physical size per se did not appear to be an important determinant of hip dysplasia.

Animals↗