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Biomedical subjects

D K Armstrong

Publications and source records attributed to D K Armstrong.

At least 37 records · Page 2Linked to original sources
PubMed1998

Evidence for a second genetic locus in Carney complex.

Carney complex (MIM no. 160980) is an autosomal dominant condition of lentiginosis, cutaneous and cardiac myxomas and multiple endocrine neoplasia. A locus for Carney complex has recently been mapped to chromosome 2p16. We have studied two Northern Irish families with this disorder. Linkage analysis was performed on the families using five highly informative dinucleotide repeat markers covering this area. Negative logarithm of the odds scores were obtained for all markers at all recombination fractions. We conclude that Carney complex is genetically as well as clinically heterogeneous.

Breast Neoplasms↗
PubMed1998

A novel insertional mutation in loricrin in Vohwinkel's Keratoderma.

A mutation in the gene encoding loricrin has recently been reported in a subset of patients with Vohwinkel's Keratoderma manifesting an associated ichthyosiform dermatosis. We have studied a further kindred with this clinical phenotype. Microsatellite marker analysis was consistent with linkage to chromosome 1q21 and direct sequencing of loricrin identified a heterozygous mutation with an insertion of a T residue at codon 209. This mutation is predicted to produce a mutant protein with a frameshift of its terminal 107 amino acids and to be 22 amino acids longer than the wild-type protein due to a delayed termination codon. The only previously reported mutation is a G insertion producing a frameshift after codon 231. The novel mutation we report is likely to have a similar functional effect on cornified envelope formation, with disturbance of transglutaminase-mediated cross-linking of envelope components, and serves to confirm the predicted role of insertional mutations in Vohwinkel's Keratoderma associated with ichthyosis.

Amino Acid Sequence↗
PubMed1998

A primer on continuous renal replacement therapy for critically ill patients.

OBJECTIVES: To characterize the multiple continuous renal replacement therapy (CRRT) techniques available for the management of critically ill adults, and to review the indications for and complications of use, principles of drug removal during CRRT, drug dosage individualization guidelines, and the influence of CRRT on patient outcomes. DATA SOURCES: MEDLINE (January 1981-December 1996) was searched for appropriate publications by using terms such as hemofiltration, ultrafiltration, hemodialysis, hemodiafiltration, medications, and pharmacokinetics; selected articles were cross-referenced. STUDY SELECTION: References selected were those considered to enhance the reader's knowledge of the principles of CRRT, and to provide adequate therapies on drug disposition. DATA SYNTHESIS: CRRTs use filtration/convection and in some cases diffusion to treat hemodynamically unstable patients with fluid overload and/or acute renal failure. Recent data suggest that positive outcomes may also be attained in patients with other medical conditions such as septic shock, multiple organ dysfunction syndrome, and hepatic failure. Age, ventilator support, inotropic support, reduced urine volume, and elevated serum bilirubin concentrations have been associated with poor outcomes. Complications associated with CRRT include bleeding due to excessive anticoagulation and line disconnections, fluid and electrolyte imbalance, and filter and venous clotting. CRRT can complicate the medication regimens of patients for whom it is important to maintain drug plasma concentrations within a narrow therapeutic range. Since the physicochemical characteristics of a drug and procedure-specific factors can alter drug removal, a thorough assessment of all factors needs to be considered before dosage regimens are revised. In addition, an algorithm for drug dosing considerations based on drug and CRRT characteristics, as well as standard pharmacokinetic equations, is proposed. CONCLUSIONS: The use of CRRT has expanded to encompass the treatment of disease states other than just acute renal failure. Since there is great variability among treatment centers, it is premature to conclude that there is enhanced survival in CRRT-treated patients compared with those who received conventional hemodialysis. This primer may help clinicians understand the need to individualize these therapies and to prospectively optimize the pharmacotherapy of their patients receiving CRRT.

Acute Disease↗
PubMed1998

A phase II "window" study of topotecan in untreated patients with high risk adult acute lymphoblastic leukemia.

To further evaluate the activity of topotecan (TPT) in acute leukemia, TPT was administered (2.1 mg/m2/day for 5 days by continuous i.v. infusion) to adult patients with previously untreated acute lymphoblastic leukemia (ALL) with high-risk features (13 patients) or relapsed ALL (1 patient). Patients achieving a partial response or significant hematological improvement received a second course. All patients subsequently received standard treatment for ALL. Because complete response was achieved in only 1 of 14 patients, the study was terminated prematurely. An additional patient achieved minimal response, and a third patient normalized her hemogram despite ongoing leukemia in the marrow. Overall, six patients had significant hematological improvement (normalization of platelet and/or absolute neutrophil count). Two patients expired due to infections during induction chemotherapy. The primary nonhematological toxicities were mucositis and diarrhea. Exposure to TPT did not appear to influence the response to subsequent standard chemotherapy. The mean steady-state TPT plasma concentration, 16.1+/-1 nM, overlapped the range of LD90 values of primary human leukemia specimens. Cellular topo I content varied over a 3-fold range, encompassing levels found previously in relapsed patients. No relationship was found between topo I expression and markers of cellular proliferation or response to therapy. In contrast, low expression of the apoptosis inhibitor Bcl-2 was associated with response to TPT therapy. TPT has significant, albeit modest, single-agent activity against high-risk adult ALL. This study demonstrates the feasibility of evaluating promising new therapeutic agents in untreated patients with acute leukemia at high risk for failure with conventional therapy.

Adult↗
PubMed1997

Altered formation of topotecan-stabilized topoisomerase I-DNA adducts in human leukemia cells.

Topotecan (TPT) is a topoisomerase I (topo I) poison that has shown promising antineoplastic activity in solid tumors and acute leukemia. In the present study, a band depletion assay was used to evaluate the ability of TPT to stabilize topo I-DNA adducts in human leukemia cell lines and in clinical leukemia samples ex vivo. This assay showed that 50% of the cellular topo I in HL-60 human myelomonocytic leukemia cells became covalently bound to DNA at an extracellular TPT concentration of 4 micromol/L. In contrast, in 13 clinical specimens of human leukemia harvested before treatment of patients with TPT, the TPT concentration required to stabilize 50% of the cellular topo I in topo I-DNA complexes ranged from 3 to greater than 100 micromol/L (median, 30 micromol/ L). Flow microfluorimetry showed that cellular TPT accumulation varied over only a twofold range and failed to provide evidence for transport-mediated resistance in the clinical samples. These observations raise the possibility that formation of topo I-DNA adducts is diminished in many specimens of refractory/relapsed acute leukemia by a mechanism that might alter topo I sensitivity to TPT.

Antineoplastic Agents↗
PubMed1997

Naevus lipomatosus cutaneous superficialis.

A young male presenting with cutaneous papules and plaques in a segmental distribution in the pelvic girdle area is reported. The clinical features were suggestive of naevus lipomatosus cutaneous superficialis, but diagnostic biopsy is essential to demonstrate the typical histopathological features and exclude important differential diagnoses such as segmental neurofibromatosis.

Adipose Tissue↗
PubMed1997

Phase I trial and pharmacologic trial of sequences of paclitaxel and topotecan in previously treated ovarian epithelial malignancies: a Gynecologic Oncology Group study.

PURPOSE: A phase I and pharmacologic study to evaluate the feasibility of administering paclitaxel (PTX) in combination with topotecan (TPT) without and with granulocyte colony-stimulating factor (G-CSF) in women with recurrent or refractory ovarian cancer. PATIENTS AND METHODS: TPT was administered as a 30-minute infusion daily for 5 days and PTX was given as a 24-hour infusion (PTX-24) either before TPT on day 1 or after TPT on day 5. Each patient received both schedules on an alternating basis every 3 weeks. Sequential dose escalation of TPT or PTX-24 without and with G-CSF resulted in five dosage permutations of TPT/PTX (mg/ m2): 0.75/135 without G-CSF and 0.75/135, 1.25/135, 1.50/135, and 1.25/170 with G-CSF. RESULTS: Twenty-two patients received 109 courses of therapy. Dose-limiting myelosuppression consistently occurred at the first TPT/PTX-24 dose level (0.75/135 mg/m2) in the absence of G-CSF support. Although the addition of G-CSF resulted in reduced rates of complicated neutropenia, the incidences of dose-limiting neutropenia and thrombocytopenia were unacceptably high after the doses of either TPT or PTX-24 were increased. Paired analysis showed similar hematologic toxicities between the two sequences of drug administration. The pharmacologic behavior of both TPT and PTX-24 was not altered by drug sequencing. Major antitumor responses occurred in 40% of patients with measurable and assessable disease, including 45% and 9% of patients with potentially cisplatin-sensitive and -resistant tumors, respectively. CONCLUSION: The recommended doses of TPT on a daily times-five schedule combined with PTX-24 in these patients were 0.75 mg/m2/d and 135 mg/m2, respectively, with G-CSF support. Although this dose of PTX has significant single-agent activity in ovarian cancer, the dose of TPT is much lower than the TPT dose at which single-agent activity has been observed. Due to the inability to administer near relevant single-agent doses of both drugs in combination, as well as the requirement for G-CSF support, further evaluations of this regimen in women with refractory or recurrent ovarian cancer are necessary before it can be recommended for previously treated patients in this setting.

Adult↗
PubMed1997

Anogenital warts in prepubertal children: pathogenesis, HPV typing and management.

The incidence of anogenital warts in prepubertal children is increasing. Modes of transmission of human papillomavirus to the anogenital area include perinatal, autoinoculation and heteroinoculation, sexual abuse and possibly indirect transmission via fomites. It was previously thought that childhood sexual abuse was the most common mode of transmission and human papillomavirus types 6 and 11 were most often detected. More recent studies, however, would suggest that perinatal infection and autoinoculation or heteroinoculation may be much more prevalent than originally thought. It has been increasingly reported that human papillomavirus type 2 is present in a significant proportion of cases. Assessment of children should be multidisciplinary and sexual abuse should be considered in every case. Treatment modalities, although similar to adult disease, are particularly dependent on individual factors. In view of the as yet unknown risk of subsequent anogenital neoplasia it is recommended that individuals should have regular follow-up on a long-term basis.

Child↗
PubMed1997

Contact hypersensitivity in patients with orofacial granulomatosis.

BACKGROUND: Orofacial granulomatosis is a clinical entity presenting with chronic swelling of the oral or facial tissues in association with histological evidence of noncaseating granulomatous inflammation. Its cause remains unclear, but a possible role of contact sensitivity to dietary components has been proposed. OBJECTIVES: This study was performed to document the prevalence of contact sensitivity to food additives in patients with orofacial granulomatosis and assess the role of elimination diets in management. METHODS: Successive patients with a clinical diagnosis of orofacial granulomatosis were patch tested to the European Standard series and an Oral Battery containing common food additives. In addition, testing for immediate contact reactions to components of the Oral Battery was performed. In selected cases, appropriate elimination diets were implemented. RESULTS: Forty-eight patients were investigated. Ten showed positive reactions to components of the Oral Battery on standard patch testing and, of these, seven showed improvement on an elimination diet. CONCLUSIONS: Orofacial granulomatosis is a heterogenous clinical entity. Patch testing permits identification of a subgroup of patients likely to benefit from dietary manipulation and allows more appropriate targeting of such treatment.

Dermatitis, Allergic Contact↗
PubMed1997

Carney complex: report of a kindred with predominantly cutaneous manifestations.

We report a four-generation kindred with the complex of myxomas, spotty pigmentation and endocrine overactivity. This kindred demonstrates a relatively limited phenotypic expression with predominance of cutaneous features. Male-to-male transmission confirms the autosomal dominant nature of the condition. We propose that pilonidal sinus may be an associated manifestation in this kindred.

Adult↗
PubMed1997

Granulomatous contact dermatitis due to gold earrings.

A young female developed persistent nodules at sites of ear piercing with gold earrings and patch testing demonstrated a positive allergic response to gold sodium thiosulphate. Histological examination of the nodules demonstrated a prominent sarcoidal-type granulomatous tissue reaction. This is in contrast to previous reports of lymphocytoma cutis type histology and was associated with the occurrence of epithelioid granulomata at the site of a strongly positive and long-lasting patch-test reaction.

Adult↗