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Biomedical subjects

P A Hughes

Publications and source records attributed to P A Hughes.

11 recordsLinked to original sources
PubMed2005

Toxicity of Bacillus thuringiensis var. israelensis formulations, spinosad, and selected synthetic insecticides to Chironomus tepperi larvae.

Three Bacillus thuringiensis var. israelensis (BTi) formulations, the bacterial metabolite spinosad, and 7 synthetic insecticides were bioassayed against 4th instars of Chironomus tepperi, a serious pest of rice in southern Australia. The BTi formulations returned 48-h product median lethal concentration (LC50) values (25 < or = 1 degrees C) of between 0.59 mg/liter (VectoBac water-dispersible granule [WDG], 3,000 international toxic units [ITU]/mg) and 2.15 mg/liter (Teknar suspension concentrate [SC], 1,200 ITU/mg). When LC50 values were adjusted to reflect nominal ITU values of the 3 products, there was still substantial variation, with LC50 values ranging from 1,770 ITU/liter (VectoBac WDG) to 2,580 ITU/liter (Teknar SC). Aquabac SC (1,200 ITU/mg) showed intermediate activity. Differential activity between formulations may reflect faster settling rates in the more active formulations, which may be a beneficial characteristic when controlling benthic species such as C. tepperi. Spinosad (24-h LC50 = 28.9 microg active ingredient [AI]/liter) and the synthetic insecticides we evaluated were all substantially more active than BTi. The highest activity was shown by the neonicotinoid compounds thiacloprid, acetamiprid, and clothianidin, which all returned 24-h LC50 values between 1 and 3 microg AI/liter. Indoxacarb and thiomethoxam showed the lowest activity of the synthetic compounds evaluated.

Animals↗
PubMed2004

Factors affecting the toxicity of Bacillus thuringiensis var. israelensis and Bacillus sphaericus to fourth instar larvae of Chironomus tepperi (Diptera: Chironomidae).

Laboratory bioassays (48h duration, 25+/-1 degrees C) were used to determine the toxicity of Bacillus thuringiensis var. israelensis (B.t.i.) and Bacillus sphaericus to fourth instar larvae of Chironomus tepperi, a major pest of rice in southern Australia. Bioassays were conducted using different combinations of larval ages and densities to determine if these factors affected toxicity. The effects of temperature and substrate type on B.t.i. toxicity were also investigated. Tests were conducted using a commercial B.t.i. formulation (VectoBac WDG, 3000ITU/mg), a spore/crystal mixture derived from the VectoBac WDG strain, and VectoLex WDG, a commercial B. sphaericus formulation (650ITU/mg). VectoBac WDG was highly toxic to fourth instar C. tepperi in bioassays using a sand substrate (LC(50) 0.46mg/L, older larvae); younger fourth instar larvae were more susceptible (LC(50) 0.20mg/L). Increasing larval densities (from 10 to 30 per bioassay cup) increased LC(50) values for both age groups, significantly so in the case of older larvae (higher density LC(50) 0.80mg/L). Use of a soil substrate increased the LC(50) value (older larvae, 10 per cup) to 0.99mg/L. Similar differences in toxicity relative to larval age and substrate type were found in bioassays using the B.t.i. spore/crystal mixture. VectoBac WDG and the spore/crystal mixture both showed similar (approximately 6-fold) declines in activity between 30 and 17.5 degrees C. At lower temperatures (between 17.5 and 15 degrees C), activity of the spore/crystal mixture declined much more rapidly than that of VectoBac WDG. VectoLex WDG showed very low toxicity to C. tepperi larvae, and the overall impact of larval age and density was relatively minor (LC(50) values 1062-1340mg/L). Autoclaving VectoLex WDG did not substantially reduce its toxicity (LC(50) 1426mg/L), suggesting that formulation additives (i.e., surfactants and other adjuvants) are responsible for much of the toxicity occurring at the high product concentrations required to cause C. tepperi mortality. Whilst VectoLex WDG was ineffective against C. tepperi, VectoBac WDG has the potential to provide selective control of this rice pest at economically viable application rates.

Animals↗
PubMed1999

The eEFIA gene family is differentially expressed in maize endosperm.

eEF1A appears to be a multifunctional protein in eukaryotes, where it serves as a protein synthesis factor as well as a cytoskeletal protein. In maize endosperm, the eEF1A concentration is highly correlated with lysine content, and eEF1A synthesis is increased in opaque2 mutants compared to wild type. To investigate the basis for the increased synthesis of eEF1A in opaque2, we characterized the genes encoding this protein and measured their relative level of expression in endosperm and other tissues. Maize contains 10 to 15 eEF1A genes that are nearly identical in nucleotide and amino acid sequences. However, these genes can be distinguished based on their 3' non-coding sequences, which are less conserved. By screening endosperm and seedling cDNA libraries, we show that most of the maize eEF1A genes are expressed, and the relative level of their transcripts varies in different tissues. At least five genes are transcribed in the endosperm, and two account for ca. 80% of the RNA transcripts. The expression of several genes is enhanced in opaque2 endosperm, although the significance of this is unclear.

Amino Acid Sequence↗
PubMed1996

Benign cervical leiomyoma leading to disseminated fatal malignancy.

A case study is reported of incomplete excision of a sessile leiomyoma of the posterior cervix followed by rapid tumor growth of the same region in a pregnancy commencing 2 months later. Cesarean section for placenta previa was followed 10 days later by hysterectomy for massive hemorrhage. The tumor was considered, following multiple review, to be a leiomyoma of the cervix with mitosis consistent with recent pregnancy. Widespread peritoneal recurrence occurred within 3 months requiring further laparotomy for excision of widespread tumor and ligation of internal iliac arteries. Death occurred 4 weeks later with widespread peritoneal occurrence. No postmortem was performed. The case emphasizes the rare potential for malignant change in histologically benign leiomyomas with no indications to this potential apart from biological behavior.

Adult↗
PubMed1996

Candida albicans arthritis one year after successful treatment of fungemia in a healthy infant.

Fungal arthritis in pediatric patients is rare and is most often associated with hematogenous spread to the affected joint. It is generally seen concomitant with, or shortly after, fungemia. We report a case of an immunocompetent patient in whom candidal arthritis developed 1 year after initial fungemia. The initial candidiasis was considered to be adequately treated with amphotericin B. The Candida isolates from the neonatal fungemia and subsequent arthritis were the some as identified by electrophoretic karyotype, restriction fragment length polymorphism analysis, and antifungal susceptibility testing. Pediatric candidal fungemia, arthritis, and their treatments are discussed.

Amphotericin B↗
PubMed1995

Measles antibodies in women and infants in the vaccine era.

The present investigation was done to determine whether measles enzyme immune assay (EIA) absorbency values were lower in women born in the vaccine era after 1963 and their infants in an upstate New York metropolitan area, an area of low measles incidence during the past 10 years compared with women born before the measles vaccine era who had natural measles. Aliquots of 202 sera from mother-infant pairs collected for other purposes from November 1990 to June 1991 at Albany Medical Center Hospital were tested by EIA. The demographic data available for analysis were maternal age and infant gestational age. Measles mean absorbency values were analyzed according to maternal age. Of 202 mother-infant pairs, 30% of mothers and 17% of their infants were seronegative (EIA < 0.16). Mothers born before 1963 and their infants had significantly higher mean EIA absorbency values than mothers born after 1963 and their infants (P < 0.002). The percent seropositive for measles antibodies by EIA for mothers born before 1963 and their infants, 87% and 94%, respectively, was significantly higher than the percent seropositive for mothers born after 1963 and their infants, 61% and 69%, respectively (P = 0.0001). Since the mean measles antibodies as measured by EIA absorbency were significantly lower in the mothers born after 1963 and their infants compared with women born before the vaccine era, the strategy for measles control in the future may have to include lowering the age of infant immunization.

Adolescent↗
PubMed1993

Uroflowmetry in the puerperium.

One hundred women underwent uroflowmetry once per day for the first 3 days after delivery, and the results compared to those of 53 nonpregnant controls in an effort to determine 1) whether urinary flow in the puerperium is different to that found without pregnancy, 2) whether uroflow parameters change as the puerperium progresses, and 3) which characteristics of a patient or her labour bear most influence upon the results of uroflowmetry. Urinary flow in the puerperium was seen to be different from that of the nonpregnant female in that mean flow rates were lower. In addition to this, voided volume, total flow time, and time to peak flow were all significantly increased on day 1, but were comparable on days 2 and 3. Other than for falling voided volumes, uroflow parameters did not alter significantly as the puerperium progressed. Correlation of the variables age, parity, baby weight, length of first and second stage, use of epidural and perineal suturing with the parameters of urinary flow failed to show any significant relationship.

Adult↗