Search PubMed⌕ Search

Biomedical subjects

I Duncan

Publications and source records attributed to I Duncan.

13 recordsLinked to original sources
PubMed1990

Direct control of antennal identity by the spineless-aristapedia gene of Drosophila.

Loss-of-function mutations in the spineless-aristapedia gene of Drosophila (ssa mutants) cause transformations of the distal antenna to distal second leg, deletions or fusions of the tarsi from all three legs, a general reduction in bristle size, and sterility. Because ssa mutants are pleiotropic, it has been suggested that ss+ has some rather general function and that the ssa antennal transformation is an indirect consequence of perturbations in the expression of other genes that more directly control antennal or second leg identity. Here we test whether the ssa transformation results from aberrant expression of Antennapedia (Antp), a homeotic gene thought to specify directly the identity of the second thoracic segment. We find that Antp-ssa mitotic recombination clones in the distal antenna behave identically to Antp+ ssa clones, and are transformed to second leg. This demonstrates that the ssa antennal transformation is independent of Antp+, and suggests that ss+ may itself directly define distal antennal identity. The results also reveal that Antp+ is not required for the development of distal second leg structures, as these develop apparently normally in Antp- ssa antennal clones. Because Antp- mutations cause deletions or transformations that are restricted to proximal structures, whereas ssa alleles cause similar defects that are distally restricted, we suggest that ss+ and Antp+ may play similar, but complementary, roles in the distal and proximal portions of appendages, respectively.

Alleles↗
PubMed1990

Mutations affecting the stability of the fushi tarazu protein of Drosophila.

We present a molecular analysis of four dominant alleles of the pair-rule gene ftz. Three of these, the ftzUal alleles, cause anti-ftz segmentation defects and homeotic transformations of the first abdominal segment to the third. These alleles are shown to be missense changes affecting two nearby proline codons. Embryos homozygous for these mutations accumulate higher levels of ftz protein than wild type and show strong persistence of ftz protein, but not RNA. These effects appear to result from stabilization of the ftz protein, since ftz stripes decay much more slowly in mutant embryos than in wild type after injection of the protein synthesis inhibitor cycloheximide. We trace the origin of segmentation defects in ftzUal embryos to repression of the pair-rule gene even-skipped by excess ftz protein during stripe sharpening. Homeotic transformations are shown to be correlated with ectopic expression of the abd-A gene of the bithorax complex. A 12-amino-acid sequence containing the proline residues altered in the ftzUal mutants appears to be conserved in the proteins encoded by other segmentation genes and the vertebrate oncogene myc and may target these proteins for rapid degradation. The fourth allele examined, T(2;3)ftzRpl(Rpl), also causes homeotic transformations and is a translocation broken within the ftz-coding region. Both ftz transcript and protein stripes are persistent in Rpl embryos, suggesting that the Rpl RNA is stabilized relative to wild type.

Alleles↗
PubMed1989

Streptococcus faecalis arthritis.

Septic arthritis due to Streptococcus faecalis is rare. We describe a case in which synovial biopsy was required for diagnosis and a new longterm antibiotic combination using ciprofloxacin and amoxicillin was successful in treating the infection. Comparison is made with previous reported cases and the usual poor outcome in this condition.

Amoxicillin↗
PubMed1988

A pilot study of carboplatin (JM8, CBDCA) and chlorambucil in combination for advanced ovarian cancer.

Forty-six patients with previously untreated, advanced ovarian cancer received carboplatin (JM8, CBDCA) and chlorambucil (CLB) to assess the efficacy and toxicity of this combination. Carboplatin 300 mg m-2 was given on day 1 with CLB 10 mg daily for 7, 10 or 14 days; 6 treatment courses were given at 4-6 weekly intervals in the absence of disease progression. Tumour response was assessed, where possible, by restaging laparotomy after 6 treatment cycles. Five complete and 16 partial remission were seen in 37 evaluable patients giving an overall response rate of 57%. The median survival of all patients was 15 months. The major toxicity was myelosuppression. Nausea and vomiting were generally minor (WHO, grades I or II) and most courses were given on an outpatient basis. Leucopenia was the major factor causing treatment delays, particularly with the 10 and 14 day CLB regimens. Thrombocytopenia was minimal in the early chemotherapy cycles but the data suggest that cumulative toxicity may occur. This combination may provide a satisfactory degree of efficacy with less toxicity than cisplatin-based regimens.

Adult↗
PubMed1986

Control of bithorax complex functions by the segmentation gene fushi tarazu of D. melanogaster.

The properties of three dominant alleles of ftz are described. These alleles cause transformations of the first abdominal segment to the third and cause alternate segment pattern deletions that are out of phase with respect to those caused by ftz null alleles. To explain the effects of these mutations, a model is proposed in which ftz+ has two roles: to subdivide the body into parasegments and to activate appropriate bithorax complex functions in alternate parasegments. According to this model, the effects of the novel ftz alleles can be understood as arising from a slight widening of the blastoderm stripes of ftz expression.

Alleles↗
PubMed1985

The abdominal region of the bithorax complex.

The homeotic mutations in the right half of the bithorax complex of Drosophila cause segmental transformations in the second through the eighth segments of the fly. A chromosomal walk in the bithorax complex has now been extended 215 kb through the right half of the complex, and lesions for over 40 mutations have been located on the DNA map. The mutations can be grouped in a series of phenotypic classes, one for each abdominal segment, although each mutation typically affects more than one segment. The mutant lesions of each class are clustered, and they are aligned on the chromosome in the order of the body segments that they affect. Complementation tests suggest interactions between widely spaced DNA regions; indeed, the right half cannot be split anywhere without some loss of function.

Abdomen↗
PubMed1977

Partial characterization of a soluble ATPase from pea cotyledon mitochondria.

A partially purified soluble ATPase (ATP phosphohydrolase, EC 3.6.1.3) from pea cotyledon mitochondria was characterized. Inhibition patterns with azide, NaF, and cold, and a stimulation by 2,4-dinitrophenol were typical of F1-ATPases from mammalian mitochondria. The enzyme hydrolysed GTP, ITP, and ATP, but not CTP, UTP, ADP, or IDP. ATPase and ITPase activities were strongly inhibited by ADP and to a lesser extent by IDP. Distinctive properties of the pea mitochondrial enzyme were activation by high concentrations of CaCl2 and stimulation by NaCl.

Adenosine Diphosphate↗
PubMed1975

Operative management of early invasive epidermoid carcinoma of the vulva.

The clinical records and surgical specimens of 60 patients with squamous cancers of the vulva less than 2 cm in size (TI) were studied. Fifty-eight patients had stromal invasion 5 mm. or less in depth. Three of the 60 patients (5 per cent) had pelvic lymph node metastases; two of these three showed invasion of vascular channels; the third patient's tumor showed cellular anaplasia. In an effort to reduce patient morbidity in radical surgery for vulvar carcinoma, while achieving comparable survival data, an operative approach less radical than radical vulvectomy, inguinal dissections, and/or pelvic lymphadenectomy is proposed for selected patients.

Adult↗